JPH01252084A - Video tape recorder - Google Patents

Abstract

PURPOSE:To execute the 2-field recording for one field period and to execute the reproduction for a next field period by providing a sub-head provided at a prescribed level difference for a main head and executing the necessary delay of one side of recording and reproducing signals in the VTR of a helical scanning azimuth recording system. CONSTITUTION:Sub-heads HDAS and HDBS provided af the rear side and front side of a track pitch TP for respective main heads are also provided besides main heads HDA and HDB. By the arrangement, on a locus on a magnetic tape due to next one-field period heads HDAs HDB, heads HDA and HDBS are moved. Thus, when recording is executed a first 1-field period head HDB and a head HDAS to which the 1-field delayed recording signal is supplied, the recording of the 2-field is reproduced by a next 1-field period head HDA and a head HDBS in which a reproducing signal is one-field-delayed. By executing the recording and reproducing with a different field, a recording condition can be monitored without a crosstalk and satisfactorily.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a video tape recorder, and is particularly suitable for application to a helical scan double azimuth recording type video tape recorder.

B. Summary of the Invention The present invention is a video tape recorder that records and reproduces video signals for two frames every frame period, thereby monitoring the recording state of the video signals while recording them. Can be done.

C. Conventional technology In the video tape recorder (VTR), the sixth
As shown in the figure, as a standard method, a pair of rotating magnetic heads HDA and HDB having positive and negative azimuth angles are disposed at positions 180° opposite each other on the rotating drum 2, and approximately 180' of the rotating drum 2 is arranged. A structure in which a magnetic tape L is wound around the corner area is used.

According to the VTR with this configuration, as shown in FIG.
A pair of magnetic heads (referred to as A head and B head) having positive and negative azimuth angles on the tape 1 HDA
and a recording track T on which video signals are recorded by HDB.
A and TB are sequentially and alternately formed diagonally across the magnetic tape 1, so that a standard format recording pattern can be formed by recording one field's worth of video signals on one recording track. There is.

D Problems to be solved by the invention By the way, in this type of video tape recorder,
When used for a long period of time, there is a problem in that the gap in the magnetic head becomes clogged with magnetic powder from the magnetic tape (hereinafter referred to as clog).

In this way, when clogs occur, the SN ratio of the reproduced signal deteriorates, and the image quality of the reproduced video deteriorates.

One possible method is to add a magnetic head on the rotating drum and monitor the video signal immediately after being recorded using the added magnetic head during recording.

However, since the signal level of the recorded signal is extremely high compared to the reproduced signal obtained through the magnetic head, it is unavoidable that the recorded signal jumps into the reproduced signal due to crosstalk. However, there was a problem in that it was difficult to monitor the recording status.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a video tape recorder that can monitor the recording state while recording a video signal.

E Means for Solving Problem E To solve this problem, the present invention provides a video tape recorder which forms recording tracks TA and TB across the magnetic tape 1 using a helical scan double azimuth recording method. , main magnetic heads HDA, HDB are arranged on the rotating drum 2, and auxiliary magnetic heads are arranged with a predetermined track pitch difference of 11 minutes from the main magnetic heads HDA, HDB. During the field period T1, a recording signal 5RECA is given to the main or sub magnetic head HDA, HDB or HDAs, HDBs, and the sub or main magnetic head HDA, HDB or HDA, HDB is provided with the recording signal 5RECA. After applying a recording signal 5IIEcl delayed by approximately one field interval T2 with respect to the recording signal SR1°, the main and sub magnetic heads HDA, HDB, HDA, HDB, during the following 1 field period T2 are applied. Main or sub magnetic head HDA for the obtained reproduction signals S, □ and S Fllm.

The reproduction signal SFllm obtained from the HDB, HDAs, HDBs is transmitted to the sub or main magnetic head HDA,
, reproduction signal S obtained from HDBS, HDA, HDB
By delaying and outputting □ by approximately one field period T1, two fields worth of video signal Sv is recorded during one field period T1, and then two fields are minute video signal SVO
to play.

By recording and reproducing video signals SV and SVO for two frames alternately every frame period TI and T2,
The recording status can be monitored while recording the video signal.

G example An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, in which parts corresponding to those in FIG.
(hereinafter referred to as the main magnetic head) are arranged, and magnetic heads HDB and HDAS (hereinafter referred to as A magnetic head (called a side magnetic head) is provided.

In this embodiment, the main and sub magnetic heads HDA and H
For the DBs, HDBs, and HDAs, an integrated head is used as a multi-head, and the distance between the gaps is selected to be as small as possible to the extent that mechanical precision can be practically satisfied.

Further, as shown in FIG. 2, the sub magnetic heads HDB and HDA are connected to the main magnetic heads HD A and H, respectively.
They are arranged at positions on the trailing side and the leading side with a height difference of 1 track pitch T with respect to DB.

Thus, as shown in FIG.
The adjacent recording tracks TA and TB are scanned at approximately the same timing, whereby recording tracks TA and TB are sequentially formed across the magnetic tape 1 in a guard panless format. be done.

On the other hand, the main and sub magnetic heads HDB and HDAS
The main and sub magnetic heads HDA are 180° opposed to each other.
and HDBs are main and sub magnetic heads HDB and HD
The recording tracks TA and TB scanned by AS are scanned one field period behind the main and sub magnetic heads HDB and HDA.

These main and sub magnetic heads HDA, HDB, HD A
s and HDB are connected to a recording/reproducing circuit 11 shown in FIG.

The recording/reproducing circuit 11 receives the video signal Sv in the recording signal processing circuit 15, and after separating it into a luminance signal and a chroma signal,
A recording signal S□c1 is generated by frequency-modulating the luminance signal and combining it with a chroma signal that has been converted to a low frequency band.

Furthermore, in the recording/reproducing circuit 11, the recording signal 5I
The IECI is output to the recording signal delay circuit 15 and the amplifier circuit 13A.

The recording signal delay circuit 15 supplies the recording signal 5R to the analog-to-digital conversion circuit 17 via the low-pass filter circuit 16.
It receives the ECI and outputs the resulting recording signal converted into a digital signal to the memory control circuit 18.

As shown in FIG. 5, the memory control circuit 18 fields the digital signal based on a switching signal SWP (FIG. 5(A)) in which the signal level is inverted every one field period TI, T2 of the video signal Sv. By sequentially storing and reading data in the memory circuit 19, a digital signal delayed by approximately one field period with respect to the input digital signal is output.

The digital-to-analog conversion circuit 20 is a memory control circuit 1
After converting the digital signal output from 8 to analog to obtain a recording signal S REC2, the low-pass filter circuit 2
1 to the amplifier circuit 13B.

The amplifier circuits 13A and 13B are configured to output the input recording signal to the sub and main magnetic heads HDA and HDB via the low retransformers 14A and 14B when the signal level of the switching signal swp falls. There is.

Thus, the sub and main magnetic heads HD A s and HD
In B, the recording signal S i
! ca and 5RECI (Fig. 5 (B) and (C)), and since the recording signal S RECl is delayed by one field period with respect to the recording signal S*tc+, two fields of video are generated. Signals are recorded on two adjacent recording tracks TA and TB on the magnetic tape 1 during one field period T1.

On the other hand, the sub and main magnetic heads HDBs and HDA transfer the video signals recorded on the recording tracks TA and TB scanned by the J main and sub magnetic heads HDB and HDA to the low retransformers 14C and 14D. The signal is output to amplifier circuits 23A and 23B via.

That is, in the sub and main magnetic heads HDB and HDA, the recording signal S□ is sent to the main and sub magnetic heads HDB and HDA. and s, 1Ec1. During the one field period T2 in which the main and sub magnetic heads HD
B and HDA scan the scanned recording tracks TA and TB, thereby converting the reproduced signal for two fields into the corresponding one.
It can be obtained during field period T2.

Therefore, during the one field period T2, the reproduced signals SPIA and S, □ (Fig. 5 (D) and (E)) obtained through the sub and main magnetic heads HDB and HDA are taken in and signal processed. Then, even if the S/N ratio of the reproduced signals S, □ and SPam deteriorates due to crosstalk, it is possible to obtain a reproduced video in which deterioration in image quality is prevented.

Therefore, it is possible to record a video signal while checking the recording state, and thereby it is possible to check the occurrence of an abnormality such as clog.

In other words, the amplifier circuits 23A and 23B receive the control signal S output from the control signal generation circuit 25 based on the switching signal swp.
Controlled by CI and SC2, during one field period T2, the reproduction signals Span and SPIIA obtained via the sub and main magnetic heads H1)B and HDA are transmitted to the adder circuit 26 and the reproduction signal delay circuit, respectively. Output to 27.

Thus, in the magnetic heads HDA, HDB, HDA, and HDBs, the recording and reproducing operations are switched every one field period (FIG. 5(F)).

Similar to the recording signal delay circuit 15, the reproduction signal delay circuit 27 receives the reproduction signal SFIIm through the low-pass filter circuit 28 to the analog-to-digital conversion circuit 29, and transfers the reproduction signal converted into the resulting digital signal to memory control. Output to circuit 30.

“The memory control circuit 30 sequentially stores and reads out the digital signals in the field memory circuit 31 based on the switching signal swp, thereby outputting a digital signal delayed by approximately one field period with respect to the input digital signal. It is done like this.

The digital-to-analog conversion circuit 32 is a memory control circuit 3
After converting the digital signal outputted from 0 to analog to obtain a reproduced signal, the reproduced signal is outputted to the adder circuit 26 via the low-pass filter circuit 33.

In this way, the reproduction signal S r,m obtained through the sub magnetic head HDB is delayed by one field period and output with respect to the reproduction signal S PBA obtained through the main magnetic head HDA. As a result, the sub and main magnetic heads H are added via the adder circuit 26 during the I field period T2.
A reproduced signal S□ can be obtained by sequentially chronologically arranging two fields' worth of reproduced signals S Pill and S PIIA obtained via the DBS and HDA.

The reproduced signal delay circuit 35 receives the reproduced signal SFN,
After separating into a chroma signal and a luminance signal and subjecting them to signal processing, they are combined into a video signal Svo and output.

On the other hand, in the normal recording or reproducing operation mode, a recording signal is sequentially applied to the main magnetic heads HDA and HDB in units of one field, or
The video signal is recorded or reproduced by demodulating the reproduced signal sequentially obtained from the HDB in l-field units.

In the above configuration, after the video signal Sv is converted into the recording signal 5IIEc via the recording signal processing circuit I5,
The signal is output to the recording signal delay circuit 15 and the amplifier circuit 13A.

Recording signal 5REel output to recording signal delay circuit 15
is delayed by one field period, and the amplifier circuit 13A
Together with the recording signal S□c1 outputted to , it is recorded on the magnetic helad tape 1 via the sub and main magnetic heads HDAs and HDB every one field period.

On the other hand, the reproduced signal S□6 obtained through the sub magnetic head HDBs is generated during one field period in which the recording signals SFIEC^, S□, and R are not provided to the sub and main magnetic heads HDAs and HDBs. During T2, the reproduced signal is applied to the delay circuit 27, delayed by one field period, and output to the adder circuit 26.

Similarly, the reproduced signal S PIIA obtained via the main magnetic head HDA is output to the adder circuit 26 during one field period T2, thereby sequentially generating the reproduced signals S, □ and S PIIA for two fields. The reproduced signals S□ arranged in time series are input to the reproduced signal delay circuit 35, and are combined with the video signal Svo and output.

According to the above configuration, the main magnetic heads HDA and HDB
In addition, sub magnetic heads HDAs and HDB are arranged on the rotating drum 2, and video signals for two frames are alternately recorded and played back every frame period. It is possible to monitor the recording status while recording the signal.

In the above embodiment, the case was described in which the sub magnetic heads HD B s and HD A s were arranged in positions close to the trailing side and the leading side of the main magnetic heads HDA and HDB. The present invention is not limited to this.
and HDA may be provided.

Furthermore, in the above-described embodiment, the main and sub magnetic heads HDA and HDBs, HDB and HDA are used as multi-head heads having an integrated structure, but the present invention is not limited to this. The magnetic head and the auxiliary magnetic head may be constructed separately.

Furthermore, in the above embodiment, the secondary magnetic head HDB
, and HDAS are disposed at the trailing side and leading side positions with a step difference of one track pitch T from the main magnetic heads HDA and HDB, respectively. However, the same effect can be obtained even if the track pitch is placed at a position with a step difference by an odd number of track pitches instead of the track pitch T, and the recording signal and reproduction signal are delayed by that amount. can.

Furthermore, in the above-described embodiment, in the normal recording or reproducing operation mode, the main magnetic heads HDA and HD
Although the case where only the circuit B is used has been described, the present invention is not limited to this, but in the configuration shown in FIG. You may also do so.

Furthermore, in the above-described embodiment, a main magnetic head H consisting of the A head and the B head is located at positions 180° opposed to each other.
Although the present invention is applied to a video tape recorder in which DA and HDB are arranged, the present invention is not limited to this, and the main magnetic heads can be arranged in various numbers and at various angular intervals. It can be widely applied to video tape recorders.

Furthermore, in the above-described embodiment, a case has been described in which the video signal Sv is received and recorded separately into a luminance signal and a chroma signal, but the present invention is not limited to this, and the present invention is not limited to this. It can also be applied to video tape recorders.

Similarly, the present invention can also be applied to a video tape recorder that outputs a video signal while separating it into a luminance signal and a chroma signal.

Furthermore, in the above embodiment, the luminance signal is frequency modulated and synthesized with the low frequency converted chroma signal to produce the recording signal S□.
The present invention is not limited to this, but can also be applied to a video tape recorder that directly frequency-modulates and records the video signal Sv.

I] Effects of the Invention As described above, according to the present invention, for each frame period,
By being able to alternately record and reproduce video signals for two frames, it is possible to monitor the recording state of the video signals while recording them.

[Brief explanation of the drawing]

FIG. 1 shows a videotape according to an embodiment of the present invention.
- A plan view showing the configuration on the rotary drum of the recorder, Fig. 2 is a side view showing the mounting position of the magnetic head, Fig. 3 is a route map showing the scanning locus of the magnetic head, and Fig. 4 is a recording A block diagram showing the playback circuit, FIG. 5 is a signal waveform diagram for explaining its operation, FIG. 6 is a plan view showing the configuration on the rotating drum of a conventional video tape recorder, and FIG. 7 is a scanning diagram of its magnetic head. It is a route map showing a trajectory. ■... Magnetic tape, 2... Rotating drum, 11... Recording and reproducing circuit, 15... Recording signal delay circuit, 27... playback signal delay circuit,
HDA, HDB, HDAs, HD Bs...
Magnetic head, TA, TB...recording track.

Claims (1)

[Claims] A video tape recorder configured to form recording tracks across a magnetic tape using a helical scanning double azimuth recording method, comprising: a main magnetic head disposed on a rotating drum; A sub magnetic head is provided with a step difference corresponding to a predetermined track pitch with respect to the main magnetic head, and the sub magnetic head provides a recording signal to the main or sub magnetic head for one field period. , After giving a recording signal delayed by approximately one field period to the recording signal to the sub or main magnetic head, the reproduction signal obtained from the main and sub magnetic heads during the following one field period is as follows. By outputting the reproduced signal obtained from the main or sub magnetic head with a delay of approximately one field period with respect to the reproduced signal obtained from the sub or main magnetic head, two fields are output during one field period. After recording video signals for 2 minutes, during the following 1 field period, 2
A video tape recorder characterized in that it reproduces a field's worth of video signals.