JPH03250445A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To record much audio information by switching duty ratio at a successive recording time and an intermittent recording time with the aid of changing the position of a magnetization inversion part in a control signal. CONSTITUTION:A positive integer multiple video in one frame is intermittently recorded. Simultaneously, in a magnetic recording and reproducing device which executes the successive recording in a prescribed time in the case that an instruction signal is inputted at the intermittent recording time, an output signal is switched to an 'H' level and supplied to a control signal generation circuit 32 by a timing circuit 31 when an alarm signal is inputted to the circuit 31 from an alarm sensor. By changing the position of the magnetization inversion part which is not used for controlling the feeding of a tape at a reproducing time, the duty ratio of the generated control signal is changed to 20% from 60% by the circuit 32. Therefore, only by adding a duty ratio detection circuit 44 to the control signal generation circuit 32 system, alarm recording/ reproducing can be executed. Besides, more audio information is recorded without sacrificing the audio information.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic recording/reproducing device, and particularly to a time lag VTR (video cheap recorder) for a flatus prevention device. and,
SUMMARY OF THE INVENTION An object of the present invention is to provide a time lapse VTR that allows easy searching for a portion (alarm recording portion) continuously recorded during an intermittent recording mode (time lapse recording mode).

(Prior art) In recent years, surveillance video cameras and time-lag streak TFIs (so-called VTRs capable of intermittent recording) have been used as crime prevention devices.
There are commercially available devices that combine these and record images of trespassers, etc. FIG. 4 shows a connection example of a conventional security device. Time-lapse VTR 1, video camera 2, monitor television (television receiver) 3, microphone 4,
and an alarm sensor 5 are connected.

When recording time lapses, V depending on the set recording time mode.
TR1 performs intermittent recording (intermittently records a video signal of a positive integer multiple of one frame). When recording this time lag,
When the alarm sensor 5 detects an illegal intruder (or when a security guard detects an illegal intruder and operates the alarm sensor 5), the alarm sensor 5 generates an alarm signal and supplies it to the VTR 1. When an alarm signal is input, the VTR 1 switches the recording mode from the time-lapse recording mode to the alarm recording mode, and performs normal continuous recording for a predetermined period of time (the time setting is variable). This is an alarm record. Alarm recording compensates for information that would be insufficient with intermittent recording.

When recording an alarm, the VTR 1 records the audio signal on the channel 2 (CH2) track of the videotape.
CUE signal (25Hz to 30Hz) Record all.

This CUE signal is continuously outputted by the audio head during playback search, and it is detected whether the CUE signal recording portion is alarm recording (continuous recording). When the CUE signal is detected, the VTRI plays the videotape at normal tape speed (the speed at which continuously recorded tape is normally played).

FIG. 5 shows a CUE signal recording/reproducing circuit. Alarm signal input from alarm sensor 5 is performed using alarm recording control diagram 8.
6 and CUE signal oscillator 7 to become a CUE signal,
The signal is recorded on a video tape via a line amplifier 8, a recording amplifier 9, a bias trap circuit 10, and an audio head (to CUE) 11. On the other hand, during reproduction search, the CIIE symbol read by the audio head 11 is outputted via the reproduction amplifier 12, 13 and the detector 14.

Further, in the audio signal circuit shown in FIG. 5, 15 is a microphone amplifier, 16 is a line amplifier, 17 is a recording amplifier,
18 is a bias trap circuit, 19 is an audio head, 20 is a reproduction amplifier, 21 is an amplifier, and 22 is a bias oscillator.

In this way, in conventional time-lab streak TR, a part of the audio track is allocated for recording the CUE signal, so the track dedicated to the audio signal becomes narrower and the amount of information in the audio signal is sacrificed. It had become. Also, C.U.
It is necessary to add a circuit for recording and reproducing the E signal, leading to a significant increase in cost.

(Problem to be solved by the invention) The problem to be solved by this invention is: What measures should be taken to create a time-lag VTR that sacrifices the amount of information in the audio signal and can reduce costs? It's all about whether it's good or not.

<Means for Solving the Problems> Therefore, in order to solve the above problems, the present invention provides a magnetic head for recording and reproducing control signals for tape feed control during magnetic tape playback onto and from trunks in the longitudinal direction of the tape. In a magnetic recording/reproducing apparatus which intermittently records a video signal of a positive integer multiple of one frame and, when an instruction signal is received during this intermittent recording, performs continuous recording for a predetermined period of time, at the time of said continuous recording. , a control gl signal switching means for switching the duty ratio of the control signal to a value different from the duty ratio during the intermittent recording, and a detection means for detecting the duty ratio of the control signal reproduced by the magnetic head. , wherein the control signal switching means switches the tutee ratio by changing the position of a magnetization reversal section that is not used for tape feed control during playback in the control signal. The present invention provides a recording/playback device.

(Embodiment) FIG. 1 is a circuit diagram showing a main part of an embodiment of a magnetic recording/reproducing apparatus of the present invention.

In this embodiment, instead of recording the CUE signal, a tape feed control signal (control signal) is recorded while changing its tutee ratio, thereby making it possible to detect the alarm recording portion. The control signal is a control signal used to control the tape feed of a conventional general VTR.

It is assumed that an alarm signal (instruction signal) does not enter the timing circuit 31 from the alarm sensor 5 during time lag recording in which a video signal of a positive integer multiple of one frame is intermittently recorded. At this time, the timing circuit 1i31 changes the output signal from low (L) level to high (H) and switches it to a bell.When an H level output signal is supplied from the timing circuit 31 to the control signal generation circuit 32, the control signal is output. The generating circuit 32 changes the tutee ratio of the control signal it generates from 60% to 25%. The Tutee ratio is
Switching is performed by changing the position of the magnetization reversal section, which is not used for tape feed control during playback, in the control signal. FIG. 2 shows a waveform diagram of the control signal. The control signal with a tutee ratio of 25% output from the control signal generation circuit 32 is
The signal is supplied to the control head 34 via the video tape, and is recorded on the control track (track in the longitudinal direction of the tape) of the video tape.

On the other hand, the H level output signal from the timing circuit 31 is supplied to the capstan servo circuit 36 via the OR circuit 35, and the capstan servo circuit 36 enters the normal continuous recording mode. At the same time, the timing circuit 31
The H level output signal output from the OR circuit 35,
The signal is supplied to the switch 38 through the AND circuit 37, and the switch 38 switches the tape intermittent feed control circuit 39 (from !11 to the gear bustan servo time F!@361I]!I. The capstan servo circuit 36 is connected to the motor drive amplifier. 40, the capstan motor 41 is controlled in continuous recording mode (alarm recording mode off).
Alarm recording is done.

After a predetermined period of time (the time setting is variable) has elapsed since the start of alarm recording, the output signal level of the timing circuit 31 returns to the L level, and the duty ratio of the control signal output from the control signal generation circuit 32 is 60.
%. Further, the switch 38 is switched to the tape intermittent feed control circuit 39 side, and the capstan motor 41 is controlled by the tape intermittent feed control circuit 39 to enter the time lag recording mode.

Then, the control signal with a duty ratio of 60% is
recorded on the control track of the videotape.

Note that the control signal generation circuit 32 is supplied with a vertical synchronization signal separated by a vertical synchronization signal separation diagram fNI42. FIG. 3 shows the state of recording on a videotape.

Next, the time of reproduction will be explained. First, in the search mode, the control signal read by the control head 34 is supplied to the tutee ratio detection circuit 44 via the switch 43. When the duty ratio detection circuit 44 detects that the duty ratio of the control signal is 25%, the detection signal is supplied from the duty ratio detection circuit 44 to the capstan servo circuit 36 via the OR circuit 35. Ru.

When the capstan servo circuit 36 is supplied with the detection signal, it switches from the search mode to the normal continuous playback mode,
The alarm recording part is played back. Note that in the search mode, the mode signal supplied to the AND circuit 37 is at L level, and the switch 38 is connected to the capstan servo concave R36.
is switched to the side.

Next, during intermittent playback (control signal tuteity ratio of 60%), the mode signal is at H level, and the switch 38
is switched to the tape intermittent feed control port R39 side. Assume that during intermittent reproduction, the duty ratio of the control signal read by the control head 34 is detected to be 25% by the duty ratio detection circuit 44. At this time, the detection signal or the duty ratio detection circuit 44
From OR times FI? 135 and the AND circuit 37,
The signal is supplied to switch 38.

When the detection signal is supplied, the switch 38 is switched to the cab stan servo circuit 36 side. The detection signal is also supplied to the capstan servo circuit 36, and the capstan servo circuit 36 controls the capstan motor 41 in the normal continuous playback mode. In this way, the part where the alarm was recorded will be recorded at the normal tape speed (continuous playback speed).
is played.

In this embodiment, since the duty ratio is switched between 25% and 60%, the judgment threshold of the duty ratio detection circuit 44 is set to 42.5%.

In this way, in this embodiment, alarm recording and/or playback can be performed simply by adding a tutee ratio detection circuit to the conventional control signal generation circuit system, so the cost is significantly reduced compared to the conventional time-lag VTR. can be achieved. Furthermore, since this embodiment does not use the audio track for tape speed control during alarm recording/playback, more audio information can be recorded without sacrificing audio information.

Further, this embodiment can detect alarm recorded portions not only in the search mode but also in the fast forward or rewind modes, and there is no risk of malfunction due to level fluctuations of the control signal.

Furthermore, the videotape recorded in this example is VI
Alarm recordings can be searched using a VTR equipped with SS (VH6 home VTR screen search method) function.

(Effects of the Invention) As described above, the magnetic recording/reproducing device of the present invention can realize alarm recording/reproduction with a circuit configuration that is significantly cheaper than conventional ones, and can also record more audio information when recording an alarm. .

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the main part of one embodiment, FIG. 2 is a waveform diagram of its control signal, FIG. 3 is a diagram showing the recording state of a videotape recorded by one embodiment, and FIG. FIG. 5 is a diagram showing a connection example of a conventional security device. FIG. 5 is a diagram showing a CUE symbol recording/reproducing circuit of a conventional time-lag VTR. 31...Timing circuit, 32...Control signal generation circuit, 33.38.4
3...Switch, 34...Control head, 3
5... OR circuit, 36... Capstan servo circuit, 37... AND circuit, three... Tape intermittent feed control circuit, 40... Motor drive amplifier, 41... Capstan motor, 42... Vertical synchronization signal separation circuit, 44... Duty ratio detection circuit.

Claims (1)

[Claims] A magnetic head for recording and reproducing control signals for tape feeding control during magnetic tape playback on tracks in the longitudinal direction of the tape, and intermittently transmits video signals of positive integer multiples of one frame. At the same time as recording, when an instruction signal is received during this intermittent recording, in a magnetic recording/reproducing apparatus that performs continuous recording for a predetermined period of time, the duty ratio of the control signal is set to a value different from the duty ratio during the intermittent recording during the continuous recording. and detection means for detecting a duty ratio of the control signal reproduced by the magnetic head, and the control signal switching means switches the duty ratio according to the duty ratio in the control signal. A magnetic recording and reproducing apparatus characterized in that tape feeding control during reproduction is performed by changing the position of a magnetization reversal section that is not used.