JPH073719B2 - Video tape recorder - Google Patents

Description

Detailed Description of the Invention

[Field of Industrial Application] The present invention relates to a video tape recorder for professionals used in broadcasting stations and the like. SUMMARY OF THE INVENTION The present invention is, for example, in a video tape recorder called SMPTE-C type format, when recording and reproducing a PCM audio signal instead of a synchronization signal in a so-called synchronous track, when recording only a PCM audio signal, By synchronizing an internal synchronization generating circuit with the supplied PCM audio signal, fluctuations in the recorded signal are removed. [Prior Art] In a so-called SMPTE-C type video tape recorder, two heads are provided on a rotating drum, and this drum is rotated at a rate of one rotation per one field, and at the same time, the circumference of the drum is rotated. The magnetic tape is wound diagonally over nearly 360 degrees of the surface and transported at a predetermined speed. The video period of the video signal is recorded in one of the two heads described above, and the signal is recorded in the other head during the period (synchronization period) in which the head is separated from the magnetic tape. Has been done. That is, FIG. 3 shows a recording pattern of the magnetic tape thus recorded. In the figure, the magnetic tape is divided into two in the width direction, a signal in the video period is recorded on an oblique track by the above-mentioned one head in the divided wide portion, and the other in the divided narrow portion. The signal of the synchronization period is recorded on the diagonal track by the head. A control track, a first audio track, a second audio track, and a third audio signal track, which are recorded by a fixed head, are provided between these parts and on both side edges of the magnetic tape. By the way, in such a format, if a so-called time base collector is used for the reproduction signal, even if the signal in the synchronization period is lost, a regular video signal can be reproduced without trouble as long as the signal in the video period is obtained. . Therefore, it has been considered to record a digitized PCM audio signal in the above-mentioned format instead of the signal in the synchronization period on an oblique track in a narrow portion. That is, in the above-mentioned conventional format, the audio signal is analog-recorded by the fixed head, but in such analog recording, the deterioration is remarkable especially when the dubbing is repeated. On the other hand, if the recording is performed digitally, the problem of deterioration during dubbing can be solved. The applicant of the present application has previously developed a video tape recorder that takes such points into consideration. That is, FIG. 4 is a block diagram of a PCM signal system for that purpose. In this block diagram, the analog audio signal supplied to the input terminal (1) is supplied to the AD conversion circuit (3) through the IO circuit (2). , Converted to digital data. This data is supplied to the data bus (4). The data on the data bus (4) is supplied to and stored in the memory (5). Further, the data stored in the memory (5) is supplied to the encoder (7) through the data bus (6), and encoding such as addition of a predetermined error correction code and rearrangement is performed. Then, the data from the memory (5) is supplied to the modulation circuit (8), the signal based on the modulated data is supplied to the recording head (10) through the recording amplifier (9),
It is recorded on an oblique track of a narrow portion corresponding to the above-mentioned synchronous track of the magnetic tape (11). The structure of the rotary drum provided with the recording head (10) is shown in FIG. In the figure, the drum is rotated clockwise and its peripheral edge is spaced at an angle of 30 degrees.
Individual heads are provided. The digital audio signals are recorded and reproduced by, for example, two heads, respectively, and the audio signal recording head (10A) is rotated counterclockwise from the position at 3 o'clock in the figure.
(10B), video signal erasing head (31), video signal recording / reproducing head (32), dummy head (33), audio signal recording confirmation reproducing head (34A) (34B), variable speed reproduction of video signal Head (35), one reproducing head (36A) for audio signals, one reproducing head (37A) for audio signals for variable speed reproduction, and the other corresponding heads (36B), (37).
B) is provided. During playback, the tape (11) to the playback head (12)
[(34A) (34B) (36A) (36B] (37A) (37B)] The signal reproduced by the demodulation circuit (1
The digital data supplied to and recorded in 4) is demodulated. The demodulated data is supplied to the data buses (15) and (16), the data of the data buses (15) and (16) is supplied to the memory (5), and the first and second decoders (17) are provided. ) (18). Demodulator circuit (14)
The address of the data detected at is supplied to the memory (5) through the address bus (19). Then, the data subjected to predetermined rearrangement, error correction, and other decoding are supplied from the memory (5) to the data bus (4). The data of the data bus (4) is supplied to the DA conversion circuit (20) to be an analog audio signal, and this signal is taken out to the output terminal (21) through the IO circuit (2). Further, the signal from the digital signal input terminal (22) is supplied to the data bus (4) through the digital IO circuit (23), and the signal from the data bus (4) is output as a digital signal through the IO circuit (23). It is taken out to the terminal (24). Further, at the time of editing, data from another video tape recorder or the like is supplied to the editing control circuit (26) through the terminal (25), and the data from this circuit (26) is transferred to the data bus (4).
And the control signal detected by the circuit (26) is supplied to the memory (5) through the auxiliary bus (27). Further, FIG. 6 shows a time chart of the recording / reproducing operation of this apparatus. Vertical lines in the figure are field boundaries. In this figure, first, A is a recording operation,

The signal AD-converted in the period of [0] is encoded in the first half of the next field [1], time-axis-compressed and read in the latter half of this field [1], and the recording heads (0A) (10B) Will be recorded at. On the other hand, B is a reproducing operation. For example, the signals reproduced by the reproducing heads (36A) and (36B) in the first half of the field [-2] are from the second half of the field [-2] to the next field. [-
1] is decoded in the first half, and the next field

The time axis is expanded during the period [0], DA converted, and taken out. Therefore, in the device described above, the same field

In order to extract the signal with [0], the reproducing heads (36A) and (36B) must be provided three fields or more ahead of the recording heads (10A) and (10B). And in the case of the above-mentioned device, since the mounting position of the reproducing heads (36A) (36B) on the rotary drum precedes the recording heads (10A) (10B) by 120 degrees, the actual preceding amount is Is. By the way, in a video tape recorder, there is a case where only an audio signal is recorded on a tape on which a video signal has been recorded (audio copyback, etc.). In that case, in the past, the video signal system of the video tape recorder was set to the playback mode, the video tape recorder was synchronously controlled so that the video signal to be played was in a predetermined standard, and the audio signal system was set to the recording mode in that state. Therefore, recording is performed on the first to third audio tracks. However, in the above-described apparatus that records and reproduces the PCM signal, the supplied PCM signal may include fluctuations such as jitter. In this case, if a signal with fluctuations is recorded on the video tape recorder that is synchronously controlled as described above, it will be recorded with fluctuations on the tape. Etc. may be added to cause a large fluctuation. In some cases, such a large fluctuation exceeds the tolerance of the playback system and the PCM signal cannot be demodulated. [Problems to be Solved by the Invention] As described above, in the conventional technique, when recording only the PCM signal, there is a problem that the variation is added and the reproduction becomes impossible. [Means for Solving the Problems] The present invention is provided with a first head (32) for recording / reproducing a video period of a video signal and a second head for recording / reproducing a period other than the video period. A magnetic tape (11) having a rotating drum driven according to a comparison between a reference synchronizing signal and a reproduction synchronizing signal in the video signal, and the magnetic tape (11) being obliquely transferred on the peripheral surface of the rotating drum. In a video tape recorder in which recording / reproduction is performed by the first head and recording / reproduction by the second head in each of the two parts divided in the width direction, a head (corresponding to the second head) ( 10A) (10B) (36A) (36B)
When recording and reproducing the PCM signal at, when recording only the PCM signal, synchronization generated in synchronization with a predetermined clock signal in the PCM signal supplied from the outside (digital input terminal (22)) A signal is a video tape recorder in which a signal is compared with a reproduction synchronizing signal in the video signal instead of the reference synchronizing signal. [Operation] According to this, since the video tape recorder is controlled in synchronization with the supplied PCM signal, the fluctuation of the recorded PCM signal is removed on the tape and the addition of the fluctuation at the time of reproduction is prevented. be able to. [Embodiment] In FIG. 1, the video signal supplied to the input terminal (50) is supplied to the recording circuit (51) and modulated into a predetermined recording signal, and the video signal of the video signal is supplied through the recording / reproducing switch (52). It is supplied to the recording / reproducing head (32). The signal reproduced by the head (32) is reproduced by the reproduction circuit (5
The video signal, which is supplied to 3) and is demodulated, is taken out to the output terminal (54). Further, during reproduction, for example, a horizontal synchronization signal (reproduction H) in the demodulated video signal is supplied to the synchronization generation circuit (55),
While various system clocks and the like are formed, the reproduction H is supplied to the system control circuit (56) and compared with the reference horizontal synchronizing signal so that the reproduction H falls within a predetermined standard. Etc. are controlled. On the other hand, the analog audio signal supplied to the input terminal (1) is
The converted PCM signal supplied to the recording / reproducing circuit (58) for PCM recording described above is supplied to the recording heads (10A) (10B). Further, for example, the signal reproduced by the reproducing head (36A) (36B) is supplied to the recording / reproducing circuit (58),
The inversely converted analog audio signal is taken out to the output terminal (21). Further, at the time of editing, etc., the PCM signal supplied to the digital input terminal (22) is supplied to the recording heads (10A) (10B) through the recording / reproducing circuit (58), and the reproducing head (36
The signal reproduced by A) (36B) or the like is taken out to the digital output terminal (24) through the recording / reproducing circuit (58). In this editing, if only the PCM signal is recorded, the clock signal of, for example, 128 fs (fs is the sampling frequency) in the PCM signal supplied to the digital input terminal (22) is supplied to the synchronization generation circuit (55). Then, the horizontal synchronizing signal (output H) formed in synchronization with this clock signal is supplied to the system control circuit (56) and compared with the reproduction H instead of the above-mentioned reference signal. That is, FIG. 2 shows a concrete example of the synchronization generating circuit (55).
In the figure, for example, the signal from the VCO (60) of 18MHz is vertical
59.94 Hz, 1/143 when the first method of horizontal 15.734 kHz,
In the second system of vertical 60Hz and horizontal 15.625kHz, it is supplied to the 1/8 frequency divider (62) through the 1/144 frequency divider (61),
The output of the frequency divider (62) is supplied to the phase comparator (63). Then, in the comparator (63), the frequency-divided signal is compared with the reproduction H supplied to the terminal (64), and the comparison output is supplied to the VCO (60) through the changeover switch (65) to obtain V.
Oscillation of CO (60) is locked to playback H. The sampling frequency fs (44.
056kHz, 48kHz, 44.1kHz), a VCXO (66) with an oscillation frequency of 1920fs is provided. Is 1/168 when is 44.056kHz, 1 when fs is 48kHz
When / 160 and fs are 44.1 kHz, they are supplied to the 1/147 frequency divider (68), and the output of this frequency divider (68) is supplied to the phase comparator (69). And when fs is 48kHz or 44.1kHz, VC
The signal from O (60) is divided by the 1/125 frequency divider (70),
This divided signal is sent to the comparator (6
9) and is compared with the signal from the above-mentioned frequency divider (68), and this comparison output is supplied to VCXO (66) and VCXO (6
The oscillation of 6) is locked to the playback H. Also fs is 44.056kHz
When the signal is output from the frequency divider (61),
It is supplied to the comparator (69) through 1) and the oscillation of the VCXO (66) is locked to the reproduction H. This locks the 1920 fs VCXO (66) to the playback H. Further, this signal is taken out to the terminal (72) and used for AD conversion. Also, the signal of 960fs is supplied to the 1/2 frequency divider (73) and is frequency-divided to the terminal (74) for DA conversion. Also, the signal of 384fs is supplied to the 1/5 frequency divider (75) and is frequency-divided to the terminal (76) for use in the digital filter. Further, the 240 fs signal supplied to the 1/8 frequency divider (77) and divided is taken out to the terminal (78) and used as the first clock signal for editing control. In addition, the signal of 128fs is supplied to the 1/15 frequency divider (79) and frequency-divided to the terminal (8
0) and used for digital IO. Further, the signal of 120 fs is supplied to the 1/16 frequency divider (81) and is frequency-divided to the terminal (82) to be used as the second clock signal for editing control. It is also fed to the 1/20 divider (83) and divided.
The 96fs signal is taken out to the terminal (84) and used for the digital filter. Further, the signal of 60 fs is supplied to the 1/32 frequency divider (85) and divided, and the 60 fs signal is taken out to the terminal (86) and used as the third clock signal for editing control. 1/40 frequency divider (8
The signal of 48fs supplied to 7) and divided is taken out to the terminal (88) and used as the bit clock of the digital filter. It is also supplied to the 1/480 frequency divider (89) and divided to 4fs.
Signal is taken out to the terminal (90) and used as a system clock. In addition, the signal of 2fs is supplied to the 1/960 frequency divider (91) and is frequency-divided to the terminal (92) to be used as a system clock. 1/1920 frequency divider (93)
The frequency fs signal is supplied to and is taken out to a terminal (94) and used as a system clock. Further, this fs signal is supplied to the 1/735 frequency divider (95) and divided, and the 1/2 frequency divider (96) waveform-shapes it to a duty of 50% and fs becomes 4
At 4.1 kHz or 44.056 kHz, an alternating signal for each field of the above-mentioned first method is taken out to the terminal (97).
Further, the fs signal is supplied to the 1/800 frequency divider (98) and divided, and the 1/2 frequency divider (99) waveform-shapes it to a duty of 50%. An alternating signal for each field of the 1 system is taken out to the terminal (100). Further, the fs signal is supplied to the 1/882 frequency divider (101), frequency-divided, and waveform-shaped to 50% duty by the 1/2 frequency divider (102). When fs is 44.1 kHz, A signal that alternates for each field of the second method is taken out to the terminal (103). Furthermore f
The signal of s is supplied to the 1/960 frequency divider (104) and divided by 1
Waveform is shaped to 50% duty by a 1/2 frequency divider (105) and f
When s is 48 kHz, an alternating signal for each field of the above-mentioned second method is taken out to the terminal (106). Furthermore, a VCXO (107) of 660fs or 528fs is provided, and the signal from this VCXO (107) is a frequency divider (10
It is supplied to 8) and divided, and further divided by 1/2 (10
9), the 1/4 frequency divider (110) and the 1/11 frequency divider (111) to supply to the phase comparison circuit (112). Then, the comparator (112) compares the frequency-divided signal with the signal from the frequency-divider (70), and the comparison output is supplied to the VCXO (107) to reproduce the oscillation of the VCXO (107). Locked to H.
As a result, predetermined system clocks are respectively supplied from the VCXO (107) and the frequency dividers (108) and (109) to the terminals (113) (11).
4) Taken out to (115). In this way, various system clocks locked to the reproduction H are formed. Further, when only the PCM signal is recorded in this circuit, the clock signal of, for example, 128 fs in the PCM signal is supplied to the phase comparator (117) through the terminal (116). The comparator (117) compares the signal from the terminal (116) with the signal from the frequency divider (79) described above,
This comparison output is sent to the VCO (60) through the selector switch (65).
Is supplied to. As a result, the oscillation of the VCO (60) is locked to the supplied PCM signal, and subsequently all system clocks and the like are locked to this signal. Furthermore, the PCM supplied from the frequency divider (62) by this
The horizontal sync signal (output H) locked to the signal is
8), the output H is supplied to the system control circuit (56) and is replaced with the above-mentioned reference signal, so that the drum motor (57) and the like are controlled so that the reproduction H coincides with the output H. It Therefore, according to this device, the video tape recorder is controlled in synchronization with the supplied PCM signal, so that the recording is performed.
The fluctuations of the PCM signal are offset on the tape, and the fluctuation-free recording is performed on the tape. Therefore, even if this recorded PCM signal is reproduced, the fluctuation is not added, and good reproduction can always be performed. When this recording is performed, the reproduction signal of the video signal deviates from the standard, so that color reproduction cannot be performed, but reproduction in monochrome is generally possible. According to the present invention, since the video tape recorder is controlled in synchronization with the supplied PCM signal, the fluctuation of the recorded PCM signal is removed on the tape, and the fluctuation during reproduction is added. Can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram of an example of the present invention, FIG. 2 is a diagram for explaining the same, and FIGS. 3 to 6 are diagrams for explaining a conventional technique. (10A) and (10B) are recording heads, (11) is magnetic tape,
(36A) (36B) is the playback head, (1) is the audio input terminal,
(58) is the PCM recording / playback circuit, (21) is the audio output terminal, (2
2) is the digital input terminal, (24) is the digital output terminal,
(55) is a synchronization generation circuit, (56) is a system control circuit, and (57) is a drum motor.

Claims (1)

[Claims] 1. A first head for recording / reproducing a video period of a video signal, and a second head for recording / reproducing a period other than the video period.
And a rotary drum driven according to a comparison between the reference synchronization signal and the reproduction synchronization signal in the video signal, on the magnetic tape that is obliquely transferred on the peripheral surface of the rotation drum. In a video tape recorder in which recording / reproduction by the first head and recording / reproduction by the second head are respectively performed on respective parts obtained by dividing the magnetic tape in two in the axial direction, When recording / reproducing PCM signals with the corresponding head, when recording only the above PCM signals, the above PCM supplied from the outside
A video tape recorder in which a sync signal generated in synchronization with a predetermined clock signal in the signal is compared with the reproduction sync signal in the video signal instead of the reference sync signal.