JP2613277B2 - Video signal recording and playback device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for recording / reproducing a video signal and an audio signal using a rotary head, and particularly to dubbing a signal accompanied by time axis processing at the time of recording. The present invention relates to a suitable video signal recording / reproducing device.

[Conventional technology]

In the case of recording a wideband video signal such as a signal of a so-called high-definition television (HDTV or high-definition television) using a rotary head mounted on a small-diameter cylinder, conventionally, two methods are mainly used. One method is to increase the relative speed between the tape heads by increasing the number of rotations of the cylinder to two to four times the normal speed, thereby expanding the recordable band. This method is called a segment recording method, in which one field of a video signal is 2 to 2 as the number of rotations of the cylinder increases.
4 segments, and each segment is divided and recorded on a different track. In this segment recording method, since one field is dispersedly recorded on a plurality of tracks, there is a disadvantage that discontinuity due to head switching occurs at the intermediate portion of the screen during reproduction. In practice, it is necessary to correct this defect and perform processing so as not to cause the discontinuity. As a specific example, for example, the technical report of the Institute of Television Engineers of Japan, VR-70-4, August 1985, " Home MUSE-V
Consideration of analog segment recording in TR ".

The second method is a channel division recording method. This method is a method of reducing a required bandwidth per channel by dividing an input video signal into signals of a plurality of channels.
An AD converter that converts an input video signal into a digital signal, a plurality of memory groups corresponding to the number of channels, a plurality of DA converters corresponding to the number of channels that convert the signal read from the memory back into an analog signal, etc. Performs the recording system signal processing. In principle, if the number of channels is 2, for example, it is possible to double the time axis of the video signal, and as a result, the required bandwidth per channel is halved. Regarding this, for example, in the National Technical Report Vol.32.No.4.August 1986, a method of dividing a band-compressed Hi-Vision signal into two channels and recording the band-compressed signal in a "band-compression VTR for Hi-Vision" is described. ing. In this method, since there is no head switching within one field as compared with the segment recording method, the processing associated with head switching is not required,
As a result of dividing one field into two channels and recording,
There is a problem that variation between channels becomes a problem, and it is necessary to suppress the characteristic difference between the channels to reproduce a good screen.

Now, as described above, when recording a wideband signal of an HDTV or the like using a small-diameter cylinder, so-called pre-processing (pre-processing) is required, and a signal actually recorded on a tape is generally input to the tape. It is in a different form from HDTV and other signals.

Here, in the system as described above, when dubbing a recorded tape to another tape, usually, 2
One VTR is used for reproduction, and the other VTR is used for recording. The video signal output terminal of the reproduction VTR is connected to the video signal input terminal of the recording VTR, and dubbing is performed. In such a system, although the intended purpose of dubbing can be achieved, the input video signal is recorded on the tape via the pre-process on the recording side, and the reproduction process is the reverse of the pre-process ( As a result of performing the post-process, there is a problem that image quality is deteriorated due to the pre-process and the post-process. Such image quality degradation is a problem common to all VTRs that perform so-called TCI (time axis compression multiplexing) processing and time axis conversion processing during recording.

[Problems to be solved by the invention]

In the above-described conventional technique, the video signal undergoes processing on the time axis that is not required for dubbing on both the reproducing side and the recording side, and the quality (image quality) of the video signal after dubbing becomes unnecessarily high. There is a problem that the number of times of dubbing is reduced correspondingly.

According to the present invention, when copying (dubbing) a video signal from tape to tape, the reproduction side and the recording side perform only minimal processing, so that degradation of the video signal after dubbing (deterioration of image quality) is prevented. It is an object of the present invention to provide a video signal recording / reproducing apparatus with reduced number.

[Means for solving the problem]

The above-mentioned object is to provide an input terminal dedicated to analog dubbing, which can directly input a signal from outside the VTR, to one of the input units of each circuit constituting the recording signal processing circuit of the VTR, The playback signal output from any of the output sections of the playback signal processing circuit is
And an output terminal dedicated to analog dubbing that can directly output to the outside of the device.

[Action]

When dubbing a recorded tape to another tape, the cable is directly connected between the analog dubbing output terminal of the playback VTR and the analog dubbing input terminal of the recording VTR via a cable, so that recording from the playback VTR is possible. Side VTR
Is supplied with the minimum required processing.

As a result, the deterioration of the video signal during analog dubbing can be kept to a minimum, and the image quality can be assured even when dubbing is repeated more times than in the conventional method.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a high-definition television signal (hereinafter, referred to as an HDTV signal) according to a 1125/60 high-definition television system directly, that is, without using a band compression system such as a so-called MUSE system.
VTR that can be recorded or reproduced on magnetic tape
Next, an embodiment to which the present invention is applied will be described.

HDTV signals are normally exchanged by four input / output signals of three primary color signals of R (red), G (green), B (blue) and Sync (synchronous signal).

In FIG. 1, 1, 2, 3, and 4 are input terminals of R, G, B and Sync signals, respectively, and three primary color signals R, G and B inputted from terminals 1, 2 and 3 are input to a matrix circuit 5 respectively. And converted into a luminance signal Y and two color difference signals C1 and C2.

On the other hand, the Sync signal input from the terminal 4 is processed by the control signal generation circuit 31, and a control signal of each product required for a memory and a motor servo circuit described later is generated.

Now, the respective signals of Y, C1 and C2 output from the matrix circuit 5 are limited in band by the reduction filters (LPF) 10, 11 and 12, respectively, and the next-stage AD converters 20, 21 and 22
And is sampled by a clock having a predetermined clock frequency. Of the video signals sampled as described above, two Y's are directly input to the memories 40 and 41.

On the other hand, since the color difference signals C1 and C2 are recorded line-sequentially as described later, C1 and C2 are input to the vertical filter 30 for limiting an equivalent frequency band in the vertical direction of the screen, and The output signal is supplied to the memories 40 and 41. The memories 40 and 41 are memories for channel A and channel B, respectively. The signals input to these memories are compressed or decompressed by a predetermined time axis by changing the frequency of the write and read clocks of the memory. Processing is performed.

Here, FIG. 2 is a waveform diagram showing the basic operation of the above-described time axis companding and division processing into two channels, A and B. FIGS. 2 (a), (b) and (c) are matrixes, respectively. The figure shows a luminance signal Y and color difference signals C1 and C2 obtained as output signals of the circuit. In these signals, one horizontal scanning period is tau _h, the validity period excluding the horizontal blanking period of the period tau _h is tau _0.

On the other hand, FIGS. 2 (d) and 2 (e) are diagrams showing the form of signals actually recorded on the tape obtained after the time axis companding and channel division processing, and FIG. (E) is a signal on the channel B side. (D)
In the signals shown in (e) and (e), the color difference signals C1 and C2 are time-axis-compressed by, for example, 0.5 times, and the luminance signal Y is time-axis-expanded by 1.5 times. The signals subjected to the time axis companding process are added with synchronization information S as shown in (d) and (e), and are time axis multiplexed.

As a result, in the signals (d) and (e), the band of the color difference signal is 1 / 0.5 times, that is, twice as large as that of the input video signals (a), (b), and (c). , The band of the luminance signal is 1 / 1.5, that is, 0.67 times. Here, assuming that the band of the chrominance signal is limited to 7 MHz by the LPEs 11 and 12 in FIG. 1 and the band of the luminance signal is limited to 20 MHz by the LEF 10, the luminance signal expansion processing results in the luminance signal Is 13.4
MHz and color difference signals are converted to signals having a band of 14 MHz.

A series of signal processing as described above, that is, compression and decompression of the time axis, and two-channel division processing can be realized by input / output control of the memories 40 and 41. Memory 40,4
The signals read from 1 are converted into DA converters 50 and 52 and LPFs 51 and 53.
Is converted into an analog signal by signal switching means 62 and 63.
Is input to

The other input terminals of the signal switching means 62 and 63 are connected to external dubbing signal input terminals 60 and 61 of the VTR, and by controlling the signal switching means, the LPF 5
Signals from the input terminals 1 and 53 and signals from input terminals 60 and 61 outside the VTR can be selected.

The signals selected by the signal switching means 62 and 63 are then subjected to FM modulation (frequency modulation) in FM modulation circuits 70 and 71, and then pass through the recording amplifiers 80 and 81 to the rotary cylinder 1
The data is recorded on the magnetic tape 105 by the four heads 101, 102, 103, and 104 attached to 00. Of the four heads, two heads facing each other at 180 °, ie, heads 101 and 1
Reference numeral 02 denotes a head for channel A, which records an output signal from the recording amplifier 80. On the other hand, heads 103 and 104, which are heads for channel B, record the output signal from the recording amplifier 81.

FIG. 3 is a diagram showing a recording pattern on the magnetic surface of the magnetic tape 105 obtained as described above. Tracks A and B are simultaneously recorded on the tape as shown in FIG.

At this time, the rotation control of the cylinder 100 and the magnetic tape 1
The travel control of 05 is performed by the motor servo control circuit 92. At the time of recording, the motor servo control circuit is controlled based on the synchronization signal input from the synchronization signal input terminal 4 and based on the reference signal generated by the control signal generation circuit 31.

The switching means 91 is a switch for switching and selecting an input signal of the motor servo control circuit 92, and selects a signal from the control signal generation circuit 31 at the time of recording as described above, and also outputs a signal from the control signal generation circuit 133 at the time of reproduction. A signal is selected, and when dubbing from another VTR, the operation is performed so as to select the signal input to the servo reference signal input terminal 90.

The signal input to the servo reference signal input terminal 90 is
For example, it is a square wave signal with a frequency of 30 Hz. This signal operates as a reference signal for both the recording VTR and the reproduction VTR servo system during dubbing, and it is possible to operate these two VTRs synchronously. It becomes possible.

Next, the operation of the reproducing process will be described with reference to FIG. The signals reproduced by the heads 101 and 102 from the magnetic tape 105 are input to the preamplifier 110, and the signals reproduced by the heads 103 and 104 are input to the preamplifier 111 and amplified.

Further, output signals from the preamplifiers 110 and 111 are input to FM demodulation circuits 120 and 121, and after being demodulated by FM, LPFs 122 and 123
Is input to The outputs of LPF122,123 are AD converter 140,14
1 and input to the sync separation circuit 132, and further output to the outside of the VTR via the channel A dubbing output terminal 130 and the channel B dubbing output terminal 131.

The signals output from these dubbing output terminals 130 and 131 are dedicated output terminals when dubbing from tape to tape using another VTR. By connecting the dubbing output terminals 130 and 131 to the dubbing input terminals 60 and 61 of the VTR used on the recording side during dubbing, that is, more precisely, the output terminals 13 and 13 on the channel A side are connected.
By connecting the input terminal 60 to the input terminal 60 on the channel A side and the output terminal 131 on the channel B side to the input terminal 61 on the channel B side, the signal of each channel can be independently converted to the FM modulation on the recording side. It will be input to circuits 70 and 71.

In this way, by providing input / output terminals dedicated to dubbing on each of the recording side and playback side of the VTR, it is possible to minimize the passage of signals to be played back and recorded, and unnecessary signal processing is performed during dubbing. Therefore, the image quality is not deteriorated during dubbing.

As described above, the reproduced signals input to the AD conversion circuits 140 and 141 are input to the memory 150 for channel A and the memory 151 for channel B, respectively, and the time axis for the luminance signal Y and the color difference signals C1 and C2 at the time of recording. Operations opposite to the compression / expansion are performed in the process of writing and reading the memory. These series of memory controls are performed by the control signal generation circuit 13
This is done by the control signal generated in 3.

The luminance signal Y output from the memories 150 and 151 is converted by the DA converter 170 and the low-pass filter (LPF) 180 into the original analog luminance signal Y. On the other hand, the color difference signal is
After being output from the memories 150 and 151, the data of the missing line is interpolated in the data interpolation circuit 160 by the line sequential method. Data-interpolated color difference signals C1, C2
Are converted into original analog color difference signals C1 and C2 via DA converters 171 and 172 and LPFs 181 and 182. The reproduced signals Y, C1, and C2 are then input to the matrix circuit 192, and three primary color signals of red (R), green (G), and blue (B) are obtained at terminals 201, 202, and 203 as output signals.

On the other hand, based on the reference signal output from the control signal generation circuit 133, a synchronization signal for reproduction is generated by the synchronization signal generation circuit 191 and output to the synchronization signal output terminal 204.

Next, the operation of the VTR when actually dubbing a tape using two VTRs according to the present invention will be described with reference to FIG. FIG. 4 is a diagram showing a connection method of two VTRs when dubbing a video signal reproduced by the VTR 1 on the reproduction side to the VTR 2 on the recording side.

In FIG. 4, in normal recording and reproduction, for example, in the case of VTR1, a video signal to be recorded is input from a video signal input terminal group 300, and a video signal reproduced from a video signal output terminal group 301 of the same VTR is output. Is output. In a conventional VTR,
Dubbing is performed by inputting the output signal from the video signal output terminal 301 on the VTR1 side to the video signal input terminal end 400 on the VTR2 side.

However, in the VTR according to the present invention, as shown in FIG. 4, the dubbing output signal obtained from the dubbing signal output terminal 303 of the VTR 1 on the reproducing side is input to the dubbing signal input terminal 402 of the VTR 2 on the recording side to perform dubbing. Is performed. As described above, by using the dedicated dubbing signal input / output terminal, dubbing work from VTR to VTR can be performed directly without passing through a complicated signal processing circuit accompanying recording / reproduction. Therefore, image quality degradation during dubbing can be minimized, and even after dubbing, it is possible to obtain better image quality than in the past.

FIG. 5 is a block diagram showing another embodiment to which the present invention is applied. FIG. 2 is a block diagram of a VTR having a configuration similar to that of the block diagram shown in FIG. 1. Components common to FIG. 1 are denoted by the same reference numerals.

In FIG. 5, dubbing input terminals 60 and 61 on the recording side are connected to DA converters 50 and 52 via signal switching means 64 and 65, respectively. On the other hand, on the playback side, channel A
Output signals of the memory 150 for channel and the memory 151 for channel B
Once through the switching circuit 152, the dubbing output terminals 130, 13
1, and input to the luminance signal DA converter 170 and the color difference signal data interpolation circuit 160.

With the above configuration, the dubbing output terminal 130
Since the signals of the A and B channels output from and 131 are outputs from the memory, that is, digital signals,
Signal exchange with the R dubbing input terminal is performed by digital signals. Therefore, when dubbing,
In exchange of signals between the VTRs, signal deterioration due to frequency characteristics, waveform distortion, etc. does not occur in principle, and image quality deterioration during dubbing can be minimized.

Further, since the dubbing output is obtained after passing through the memories 150 and 151 as described above, by using the memory as a simple delay circuit, the delay amount of the video signal reproduced from the head can be reduced within the range of the maximum capacity of the memory. It is possible to control with. This means that, for example, a VTR in which video is recorded analog and audio is recorded digitally
Thus, when dubbing is performed, it is very useful to compensate for so-called AV (audio, video) delay.

FIG. 6 shows the tape pattern shown in FIG.
FIG. 7 is a diagram showing a tape pattern when digital audio is recorded in an overlap area on the tape, wherein the digital audio is recorded in a digital audio recording area on the output side in the head scanning direction.

FIG. 7 is a diagram for demodulating a digital audio signal recorded in the above-described form to obtain an original audio signal.
FIG. 2 shows a block diagram of a digital audio reproduction signal processing system.

In FIG. 7, signals reproduced by the magnetic heads 101 and 102 are sent to a preamplifier 110 via a head output signal terminal. After the head output signal is amplified by the preamplifier 110, the waveform equalization circuit 500 corrects the amplitude and phase distortion received during the recording / reproduction process,
It is input to a comparator 502 having 501. The comparator 502 converts the input signal into a binary digital signal by comparing the magnitude of the input signal with the reference voltage source.

The digital signal generated in this manner is input to the data strobe circuit 503 to generate a strobe clock, and further input to the error detection / correction circuit 504 using the memory 505 as a buffer memory. In this error detection / correction circuit, the reproduced digital signal is subjected to detection / correction or correction processing for a code error generated in the recording / reproduction process.

The memory 505, in the error detection and correction process,
This is a buffer memory for temporarily storing digital data, and has a memory capacity corresponding to an audio signal transmitted in one field or one frame period of a normal video signal. The digital signal processed by the error detection / correction circuit is converted to the original analog audio signal by the DA converter 506 and output to the audio output terminal 507.

FIG. 8 is a diagram showing the above audio signal processing in chronological order, where (a) shows the field timing of the video signal, where a high level indicates an even field and a low level indicates an odd field. (B) shows the reproduction processing timing of the audio signal, and the hatched portion shows the reproduction time of the digital signal recorded in the overlap area in FIG.

Of these digital signals, the signal reproduced at the time indicated by the numeral 0 is subjected to data delay due to the above-described error correction processing as shown in FIG. Output as a signal.

On the other hand, FIG. 8 (c) shows the reproduction processing timing of the video signal. For example, the signal of the field indicated as 0 is
In order to ensure the same characteristics as the audio signal, the signal is output after being delayed by one frame.

As described above, by using the memories 150 and 151 on the reproduction side in FIG. 5 as a simple delay line, it is possible to compensate for the AV delay caused by the audio delay caused by digital processing and to perform dubbing using a dubbing terminal. Becomes

In addition, as described above, when dubbing is performed via the memories 150 and 151, these memories can be used as buffer memories for time axis error correction, and output from the memories 150 and 151 via the switching circuit 152. It is also possible to output the output signal for dubbing as a signal in which the time axis error is corrected.

At this time, a clock synchronized with the time axis error included in the reproduced signal is used as a sampling clock for AD conversion and a clock for generating a write address to the memory, while a clock read from the memory is accurately read by a crystal oscillator. It is necessary to use a proper clock.

The above-described embodiments shown in the block diagrams of FIGS. 1 and 5 are all examples in a VTR for recording and reproducing an HDTV signal. However, as an input signal, the HDTV signal is band-compressed and transmitted. The signal may conform to the MUSE system. Although not shown in the figure, in a VTR for recording after inputting a so-called MUSE signal and performing a time axis conversion process, the dubbing terminal is connected before the FM converter (recording input) as in the embodiment of FIG. Side) and after the FM demodulator (reproduction output side), dubbing can be performed by connecting two VTRs between the above dubbing terminals.

The present invention is also applicable to a VTR that records an existing TV signal such as MTSC, PAL, SECAM and the like.

Further, in the above-described embodiment, only the case where the input signal is divided into two channels A and B for recording is shown. However, the present invention is not limited to the two-channel division system, and may be applied to a VTR of a system without channel division. However, the present invention is also applicable to a multi-channel division system of two or more channels.

Similarly, the present invention is also applied to a reproduction-only VTR or a VDP (video disc player) for reproducing video information from a recorded disk, and a dubbing machine or an editing machine for dubbing or editing between recording media. By configuring these devices with the minimum configuration required in the recording / playback process during dubbing, not only can the image quality during dubbing be improved, but also the dubbing machine and editing machine can be used. It is also possible to reduce costs.

〔The invention's effect〕

As described above, according to the present invention, at the time of analog dubbing from a recorded tape to another tape, by using an input / output terminal dedicated to dubbing, only the minimum signal processing circuit required in the dubbing process is used. It is possible to perform dubbing via the terminal. As a result, it is possible to minimize the image quality deterioration during dubbing, to improve the image quality of the video signal after dubbing, and to provide a video signal recording / reproducing apparatus having excellent functions except for the above-described problems of the related art. Can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a waveform diagram showing a signal processing process of FIG. 1, FIG. 3 is a tape pattern diagram in the embodiment of FIG. 1, and FIG. FIG. 5 is a block diagram showing another embodiment of the present invention, FIG. 6 is a tape pattern diagram when digital audio is recorded, and FIG. 7 is a digital audio signal processing circuit. FIG. 8 is a block diagram of the audio and video signal processing. 20,21,22 AD converters 40,41 Memory 50,52 DA converters 61,62 Dubbing signal input terminals 70,71 FM modulation circuits 120,121 FM demodulation circuits 130,131 Dubbing signal output terminals 140,141 ... AD conversion circuit 150,151 ... Memory 170,171,172 ... DA converter.

Claims (1)

(57) [Claims] A first AD converter for converting a video signal (1, 2, 3, 4) input from a video signal input terminal into a digital signal; A first method of temporarily storing the digital signal output from the converter for a predetermined time and outputting the digital signal in a predetermined order
Memories (40, 41), a first D / A converter (50, 52) for converting a digital signal output from the first memory into an analog signal, and an output signal of the first D / A converter A frequency modulator (70, 71) for performing frequency modulation, and a rotary head (101, 102, 10) for outputting an output signal of the frequency modulator.
Frequency demodulator (120, 121) for recording on magnetic tape (105) by means of 3,104) and for frequency demodulating the signal read from magnetic tape by the rotary head during reproduction
A clock generating means (133) for generating a clock synchronized with a time axis fluctuation included in the demodulated signal from the signal demodulated by the frequency demodulator; and a clock generated by the clock generating means as a sampling clock. A second AD converter (140, 141) for converting the demodulated signal into a digital signal; and a second AD converter for temporarily storing the digital signal output from the second AD converter for a predetermined time and outputting the digital signal in a predetermined order.
(150, 151), and a second DA converter (170, 171, 172) for converting a digital signal output from the second memory into an analog signal, and configured to reproduce the original video signal. In the video signal recording / reproducing apparatus, on the recording side, an input terminal (60, 61) dedicated to a dubbing signal connected to an input terminal of the frequency modulator (70, 71); a signal from the dubbing signal input terminal; Signal switching means for selecting a signal from the video signal input terminal (62, 6
And 3) an output terminal (130, 131) dedicated to a dubbing signal connected to an output terminal of the frequency demodulator (120, 121) during reproduction, and input / output via the dubbing signal input terminal during tape dubbing. A video signal recording / reproducing apparatus characterized in that the video signal recording / reproducing apparatus is configured to perform the processing.