JPS6038990A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To prevent deterioration of picture quality by recording a pilot signal recorded on a video track when the recording is finished while replacing the order and tracing the video track where the order of the pilot signals is replaced at the reproduction mode for consecutive recording so as to avoid duplicatedly recorded part. CONSTITUTION:The pilot signal fm is superimposed on a video signal VD by an adder 12, fed to video heads 16A, 16B via a recording amplifier 13, a recording/ reproduction changeover switch 14 and a head changeover switch 15 and recorded on a video tape 17. A mixed pilot signal fmm' including alpha and beta components being a beat signal due to a crosstalk component between the pilot signal on the traced track and the pilot signal on the adjacent track thereto is outputted from a mixer 22. A deviation signal SF in response to the difference between the alpha and beta components is outputted from a differential amplifier 27, and a required track is traced accurately by applying tracking servo so that the level of the alpha and beta components is made identical.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus for image information such as a VTR, and more particularly to a magnetic recording and reproducing apparatus capable of continuous shooting (editing).

In general, magnetic recording and reproducing devices with rotating magnetic heads such as VTRs cannot perform so-called splice editing, but editing can be performed by performing pause operations and the like.

However, with a simple pause operation, the next recording starts regardless of the track that has already been recorded, so the arrangement of the tracks becomes discontinuous in this part, the control signal becomes discontinuous, and so on during playback. A problem arises in that the tracking servo becomes disconnected in this part, causing the image to become distorted.

Conventionally, in a magnetic recording/reproducing device, the video tape is rewound while counting the control pulses already recorded on the video track from the last video track on which signal recording has already been completed until the counted value reaches a predetermined value. The videotape is stopped once at the point where the number of controller pulses reaches 1, and then the videotape is run in the normal running direction to enter the playback mode. During this playback mode, racking is performed to 1, and the count value of the control 1-roll pulse is set to the above-mentioned count value. There is a device in which the reproduction mode 1- is switched to the recording mode when the numerical values substantially match.

However, in such a magnetic recording/reproducing device, recording must be started from a video trunk several tracks before the final video track due to the sensitivity of the control amplifier and the accuracy of the video tape drive system. did not become.

As a result, there was a double-recorded part where a new signal was recorded on the video trunk where the signal had already been recorded, and during playback, this double-recorded part generated beat noise and deteriorated the image quality. .

■ This invention was made in view of the above points, and it is an object of the present invention to prevent deterioration of image quality by preventing double recording from occurring during splicing, especially in a magnetic recording and reproducing device that uses the pylon 1 method for tracking. Therefore, the magnetic recording and reproducing apparatus according to the present invention changes the order of the pilot signals to be recorded on the video track when recording is completed, and records the pilot signals in the video track in a reproducing mode for continuous shooting. Pyroir 1 caused by tracing a video track where the order of the pilot signals has been swapped.
-The system switches from the play mode to the record mode when a change in the crosstalk component of the signal is detected.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram of main parts showing an embodiment of the present invention.

In the figure, a pilot rotation controller 1 outputs binary control signals SA and S for controlling rotation of pilot signals in order to perform tracking using a pilot method.

Control signals SA and SB from the pilot rotation controller 1 to roller 1 are sent to switches 2A, respectively.

Control filter is applied between contacts a and c of 2 +3 and through switch O A, and between contacts b and c of inverters 48 and 4B and switches 2AI and 2B and through switches 3A and 3B.
(No. g 11) A is input to the pylon (-signal generator 5) as PI3.

This pilot signal generator 5 outputs four types of pylon I signals fm (f1 to f, 1) having different frequencies according to the combination of the control signals 1)A and l]13.

That is, for example, the control signals PA and I-'B are each ゛o''
, send signal f1 to pylon I when ``o'', ``O'',]
”, pylon 1-signal f2, “]”, “O”
The pilot signal f3 is outputted at the throat, and the pilot signal f4 is outputted at the time of ]'', 1''.

Also, there is a relationship between the frequencies of the pylon 1 signals f1 to f4 such as A, etc., as follows: lf + f21 - 1f3 f41 - α lf2 f31 = lf, + ft 1 - β, for example, f, = 102KH2, r2 ”l l-7Kl(
Z, f3 = +62KI-1 z, f4 ”1
47 KI (Z), the double frequency difference α and β becomes α=15 KH2, β=45 K HZ.

On the other hand, the recording end switch 6 is turned on when recording ends, for example, when a pause button or a stop button is operated.

The recording end detection circuit 7 switches the recording end switch 6, /1':
When turned on, a positive switching signal SC for switching the switches 2A and 2B from the contact a side to the contact side is outputted via the AND circuit 8.

That is, this recording end detection circuit 7 and switches 2A, 2
11 and inverters 4A and 413 constitute order switching means.

In addition, in this magnetic recording and reproducing apparatus, when the switching signal SC is output from the recording end detection circuit 7, the process of recording end (4) in the conventional magnetic recording and reproducing apparatus is performed by two bidet 1st ranks. This will enable recording.

The edge detection circuit 9 outputs a positive detection signal SD to the AND circuit 8 when it detects a rising edge (or a falling edge) of the head switching pulse PC.

The hold circuit 10 receives the switching signal S via the AND circuit 8.
The video head traces one field from the time C is input; and when the required time has elapsed, it outputs a switching signal SE that turns off the switch 13B.

The pilot signal fm from the pilot signal generator 5 is superimposed on the video signal (chroma signal and luminance signal) VD by the adder 12, and is input to the recording amplifier 13 as the recording signal VΔ.

The recording amplifier 13 amplifies the recording signal VA from the adder 12 and supplies it to the video head IEIA or IEIB selected by the head changeover switch 15 via contacts a and c of the recording/playback changeover switch 14. .

Note that the recording/playback selector switch 14 has contact a during recording.
During reproduction, the head changeover switch 15 is switched to the contact a side or the contact side by the head changeover pulse PC.

The video heads 16A and 1611 are single-rotation magnetic heads, and output signals from the recording amplifier 16 are transferred to the video tape 17.
The signal recorded on the video tape 17 is also read and output.

On the first day of the playback amplifier, the playback signals from the video head IE) A and 16B are connected to switch 15 and contact C- of switch 14.
The signal is inputted via the signal line B, and is output to a demodulator of a reproduction system (not shown), and is also output to the bandpass filter 21 of the crosstalk filter FIH 120.

This band-pass filter 21 filters the pilot signal (reproduction pilot 1) of the reproduction signal ■Δ' from the reproduction amplifier 1
- signal) f ITI' (m=1 to l]) is passed through.

The mixer 22 mixes the reproduced pylon 1-I number fm' that has passed through the band-pass filter 21 with the pylon 1-signal f II+ from the pylon 1 to the signal generator 5, and calculates the frequency differences α and β between the two signals. Mixed pylon 1 containing the beat signal of
A signal fvn' is output to.

The bandpass filter 23 extracts the frequency α component (hereinafter referred to as “α component”) in the B1-signal of the mixed pilot signal fmm′ from the mixer 22, and the bandpass filter 24 similarly extracts the frequency β component (hereinafter referred to as “α component”). (hereinafter referred to as the "β component") is allowed to pass through.

Detectors 25 and 26 detect the levels of the α component and β component, respectively, and output them to the differential amplifier 27.

The deviation signal SF corresponding to the level difference between the α component and the β component output from the differential amplifier 27 is generated by the head switching pulse P.
When the switch 29, which is switched to the contact a side or the contact side according to C, is switched to the contact side, it is reversed by the inverter 28, and when the switch 2B is switched to the contact a side, the switch 29 is switched to the contact a side, and the switch 29 is switched to the contact a side. Deviation signal SF'
is output as

The deviation signal SF' from the crosstalk detection circuit 20 is input to the tracking servo system to perform tracking control, and also turns on the switch 61 which is turned on by the servo lock signal SG output when the tracking servo is off. A switching circuit 32, which is a mode switching means,
is output to.

When the deviation signal SF' reaches an error level, that is, when a difference occurs between the two crosstalk components, the recording/reproduction changeover switch 14 is switched from the contact side to the contact a side at a predetermined timing.

Next, the operation of this embodiment configured as described above will be explained with reference to FIGS. 2 and 6.

In FIG. 2, the direction of arrow A indicates the running direction of the video tape, and the direction of arrow B indicates the rotation direction of the video head.

First, the recording and reproducing operations related to pilot type tracking will be explained. In addition, at this time, switches 2A and 2B
switches to contact a side, switch 3A, ! It is assumed that l is in the on state and the switching circuit 32 is not operated.

First, during recording, the recording/reproduction changeover switch 14 is switched to the contact a side.

And the pilot rotation controller 1 is
The control signals SA and SB are changed from [00j→“01”→rlOJ
→ “11” → “00” are input to the pilot signal generator S as outputs PA and PB.

Thereby, the pilot generator 5 outputs the pilot signal fm in the order of f1→f2→f3→f4→f1.

This pilot signal fm is converted into a video signal V by an adder 12.
D, and the recording amplifier 13. The video tape 1 is supplied to the video head IE)A or IGB via the recording/playback switch 14 and the head switch 15.
7 is recorded.

That is, during recording, as shown in FIG. 2, for example, the pilot signal f1 is applied to track T1, the pilot signal f2 is applied to 1-rack T2, the pylon 1-signal f3 is applied to track T3, and the pilot signal f4 is applied to ranks 1 to T4. , pilot signal fl on track T5, and so on, the pilot signals f1 to f4 are circulated and recorded together with the video signal VD.

Next, during reproduction, the recording/reproduction changeover switch 14 is switched to the contact side.

Then, from the video tape 17, the video head 16Δ, 1
The regenerated pilot signal f included in the regenerated signal VA' read out alternately by the reproducing amplifier 6B and amplified by the regenerative amplifier 1.
m' is separated from the video signal VD by the bandpass filter 21 of the crosstalk detection circuit 20 and input to the mixer 22.

At this time, the reproduced pilot signal fm' includes the pilot signal recorded on the track to be traced by the video head 16A and IEIB, as well as the pilot signal recorded on the track adjacent to that track.

For example, when tracing the track T2 shown in FIG. 2, the reproduced pilot signal fm' includes the pilot signal f2 of the track T2 and the pilot signal f1 of the track T1.
and a pilot signal f3 for track T3.

On the other hand, during reproduction, the pilot signal of the track to be traced from the pylon I- (i generator 5) is input to the mixer 22 under the control of the pilot rotation controller 1.

For example, when tracing the track T2 shown in FIG. 2, a pilot signal f2 is input from the pilot signal generator 5 to the mixer 22.

Therefore, from the mixer 22, the pilot signal of the truck to be traced and the pylon 1 signal of the adjacent truck are outputted from the mixer 22.
-Mixed pilot signal f mm' containing α and β components that are signals to Be 1 due to crosstalk components with the signal
is output.

For example, when racing track T2 shown in FIG. 2, the frequency is (f+f2) as a crosstalk component.
) and the β component of (f2 f3) are output.

The α and β components due to these crosstalks are separated by a bandpass filter 23.24, and the detection circuit 25.2
6, the level is detected and input to the differential amplifier 27.

At this time, if the video heads 16A+16I3 are accurately racing the required track, the α and β components will be at the same level, but if they are off the desired track, crosstalk will occur on the off track. Due to the increase in , the α component or the β component increases in accordance with the amount of deviation.

For example, when racing the track T2 shown in FIG. 2 by 1, the α component becomes large when it deviates toward the track T1, and the β component becomes large when it deviates toward the track T3.

Then, the differential amplifier 27 outputs a deviation signal SF corresponding to the difference between the α component and the β component.

Therefore, by applying tracking servo so that the levels of the α and β components are the same, the desired 1-rack can be accurately traced.

Note that the increase/decrease relationship between the α component and the β component is opposite when the video head to be traced is video head IEiA and when it is video head 16B, so the switch 2 is switched by the head switching pulse PC. In response to switching between the video heads 16A and 16B, the deviation signal SF from the differential amplifier 27 is inverted and converted into a deviation signal SF'.
I am trying to output it as .

Next, the continuous shooting operation will be explained.

First, during recording, tracks T1 to T shown in FIG.
When recording up to track n-3 is completed and the recording end switch 6 is turned on during recording of track T n -2, the recording end detection circuit 7 outputs a switching signal SC.

At this time, if the recording system was originally supposed to end processing at the end of track Tn-2, this magnetic recording/reproducing apparatus continues processing for two more tracks.

Therefore, for example, if the head switching pulse PC rises to scan the 1-rack 'J''n-1, the edge detection circuit 9 detects the rising edge and outputs the detection signal SD. The circuit 8 becomes open.

As a result, the switching signal SC from the recording end detection circuit 7
is input to switches 2A and 2B, and switch 2A+2n
Since the control signals SA and PB from the pilot rotation controller 1 are inverted by the inverters 4At and 4B, they are input to the pilot signal generator 5 as control signals PA, PB.

Therefore, when scanning the track Tn-1 shown in FIG. 2, for example, the control signals SA and SB from the pilot rotation controller 1 are i'' and ``o'',
The signal fm sent from the pilot signal generator 5 to the pilot 1 corresponding to this is originally the pilot signal f3.

However, since the control signals SA and SB are inverted, the control signals PA and pB become "O" and "1", so the pilot signal f2 is output from the pilot signal generator 5 and the signal shown in FIG. 1~lack T n-1 as shown
A pilot signal f2 is recorded.

Similarly, the track Tn shown in FIG.
, SB are '1', '1', and the control signals PA, PR which are inverted thereof are 'o'',=o'', so the pilot signal f1 is recorded.

In this way, when recording is completed, the original order of the pilot signals is changed and recorded.

Then, corresponding to the point in time when recording for these two tracks is completed, the hold circuit 1o outputs a switching signal SF to turn off the switches 3A and 3n.

In this way, for example, as shown in FIG. 2, the pilot signal fl is transmitted from tracks T1 to Tn.

f 2 r f 3 rf4 rfl...fl +f
2 +f2 rfl is recorded together with the video signal VD, and the recording ends.

Next, when performing splicing, the videotape is rewound by a predetermined amount, that is, by the number of steps necessary to ensure tracking during playback.

At this time, for example, if the tape is rewound to the 1-rack TI shown in FIG. The 1-racking servo is applied based on the deviation signal SF' from the Talostalk detection circuit 20 to control the rotational speed of the capstan motor (not shown) and align the video heads 16A, 16B with the playback track.

Then, when the 1-ranking is obtained, the deviation signal SF' is 0.
'', the servo lock signal SG is output, and the switch 31 is turned on.

Thereafter, when the video head 16A traces the track Tn-1 on which the pylon 1 signal f2 shown in FIG. 2 is recorded, for example, the adjacent track T''n-2.

A pilot signal f2+fl is recorded in Tn. That is, the same pilot signal f2 is recorded on track Tn-+ and track Tn-2.

Therefore, at this time, since only the α component of (f+f2) is detected, the deviation signal S F output from the differential amplifier 27 is, for example, as shown in FIG. At time t1 when the number is 1, it becomes "-".

As a result, if the switch 2 is switched to the contact a side at this time, the deviation signal SF' which is the same as the deviation signal SF
is input to the switching circuit 32 via the switch 31, and the switching circuit 32 switches the recording/playback switch 14 from the contact side (playback side) to the contact a side (recording side) at the time when tracing of the track Tx+ is completed. Switch.

Therefore, the recording mode is entered and recording is started from the track Tn+1, and at this time, the signal f1 is recorded on the pylon 1 in the rack Tn+1.

In addition, when playing the videotape spliced in this way from, for example, trunk T1 to track Tn+x in FIG. 2, the deviation signal SF is It becomes "-" at time t1 in the diagram.

Then, when racing rack r n to 1, since the pilot signal f1 is recorded in racks T n ++ from 1 to 1, only the α component of (j+f2) is detected, so the deviation signal SF becomes "-" even at time point 12 in FIG. 3 when tracing this track Tn.

However, when tracing this track Tn, the head switching pulse PC switches the switch 2 to the contact side, so the deviation signal SF is inverted by the inverter 28.

Therefore, the deviation signal SF' becomes "-" at time t1 and becomes "+" at time 12, as shown in FIG. 6(b).

In this case, the capstan motor does not follow the error of about 2 tracks, so it immediately moves to the next 1-track after track Tn.
The video head moves while keeping tracking at rank Tn÷1. Moreover, this error is almost canceled out by "+" and "-".

In this way, in this magnetic recording and reproducing device, when recording is completed, the order of the pilot signals is changed and recorded, and when playing back for splicing, the position where the pilot signals were recorded in the changed order is checked. Since the reproduction mode is switched to the recording mode when detected, there is no risk of double recording of image signals, and the image quality will not deteriorate due to the occurrence of B1~.

As described above, according to the present invention, deterioration in image quality due to continuous shooting does not occur in a magnetic recording/reproducing device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a main part showing an embodiment of the present invention, FIG. 2 is an explanatory diagram showing a pattern on a videotape used to explain the operation of FIG. 1, and FIG. FIG. 3 is a waveform diagram showing an example of a deviation signal output from a crosstalk detection circuit. 1... Pilot rotation controller 2 A,
211・Selector switch 5...Pylon 1-Signal generator 6...Note 8# Completion switch 7...Record end detection circuit 12...Adder 14...Record/playback selector switch 15...Head selector switch 16A , 1613...Video head 20...Taroist detection circuit 32...Switching circuit

Claims (1)

[Claims] 1. In a magnetic recording/playback device that performs tracking using a pilot method, the video tape is rewound a predetermined amount from the video trunk where recording has finished, and tracking is performed in playback mode to take continuous shots. pylon 1 to be recorded on the pylon 1 - order switching means for switching the order of the signals and recording the signals, and a position at which the pilot signals are recorded with the order switching based on the detection result of the crosstalk component of the pilot signal in the playback mode. What is claimed is: 1. A magnetic recording and reproducing apparatus comprising: means for detecting a magnetic field; and mode switching means for switching from a reproduction mode to a recording mode in response to a detection signal from the means.