JPH0630124B2 - 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 a digital audio signal is recorded on a so-called synchronous track instead of the synchronous signal, a recording head for recording the recorded digital audio signal. The playback heads provided after this perform playback processing to check the recording and provide a system for directly playing back digital audio signals. The drive of the memory used for the recording / reproducing process is controlled so that the time point of the reproduced signal coincides with that of the signal. [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. 5 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, in the above-mentioned format, it was considered to record a digitized audio signal instead of the signal of the synchronization period on the diagonal track of the 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. On the other hand, in the above-mentioned video tape recorder, it is conceivable to provide a reproducing head at a position following the recording head and reproduce a signal immediately after recording to confirm recording. Further, it has been proposed to demodulate the signal immediately before being supplied to the recording head to extract a so-called EE mode signal. In that case, conventionally, since there is a distance from the recording head to the confirmation reproducing head, a deviation occurs between the confirmation reproduction signal and the EE mode signal, which is preferable when the signals are compared by switching between them. Could not be done. [Problems to be Solved by the Invention] As described above, in the conventional technology, there is a difference between the time points of the confirmation reproduction signal and the EE mode signal, which makes it impossible to compare the two signals satisfactorily. was there. [Means for Solving the Problems] The present invention has a rotary drum provided with a first head for recording a video period of a video signal and a second head for recording a period other than the video period. Then, the recording by the first head and the recording by the second head are performed on each part of the magnetic tape, which is diagonally transported on the peripheral surface of the rotary drum, divided into two in the width direction. In a video tape recorder configured to be performed, when recording is performed by supplying a recording process including AD conversion and time axis compression to an audio signal and supplying the same to a head corresponding to the second head, recording is performed.
The third heads (34A) (34A) (34A)
B) is provided, and a reproduction signal (decoder (17) (18)) including a reproduction signal by the third head and time axis expansion and DA conversion corresponding to the recording processing is obtained to obtain a first reproduction audio signal. , The recording processed signal is directly supplied to the reproduction processing system (switches (28) and (29)) to obtain a second reproduction audio signal, and the time points of the first and second reproduction audio signals coincide with each other. The video tape recorder is configured to control the drive of the memory (5) used in the recording / playback process. [Operation] According to this, it is possible to obtain the signal that has been confirmed and reproduced and the signal in the EE mode, and it is possible to favorably compare both signals by matching the time points of these signals. [Embodiment] In the block diagram of FIG. 1, an analog audio signal supplied to an input terminal (1) is supplied to an AD conversion circuit (3) through an IO circuit (2) and converted into digital data. This data is supplied to the data bus (4). This data bus
The data of (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 by the modulated data is supplied to the recording head (10) through the recording amplifier (9), and the above-mentioned synchronization of the magnetic tape (11) is performed. It is recorded on an oblique track of a narrow portion corresponding to the track. Here, the structure of the rotary drum provided with the recording head 10 is as shown in FIG. In the figure, the drum is rotated clockwise, and 12 heads are provided on the periphery of the drum at angular intervals of 30 degrees. The digital audio signals are recorded and reproduced by two heads respectively, and the audio signal recording heads (10A) and (10B), the video signal erasing head (31), and the video signal are rotated counterclockwise from the position at 3 o'clock in the figure. Recording / playback head (3
2), dummy head (33), playback head (34A) (34B) for audio signal recording confirmation, variable speed playback head (35) for video signal, one playback head (36A) for audio signal, variable speed playback There is provided one reproducing head (37A) for the audio signal for audio, and the other corresponding heads (36B) and (37B), respectively. Furthermore, during playback, the tape (11) is read from the playback head (12) ((3
4A) (34B) (36A) (36B) (37A) (37B)] is supplied to the demodulation circuit (14) through the reproduction amplifier (13), and the recorded digital data is demodulated. This demodulated data is supplied to the data bus (15) (16) and the data bus (1
The data 5) and (16) are supplied to the memory (5) and also to the first and second decoders (17) and (18), respectively. The address of the data detected by the demodulation circuit (14) is supplied to the memory (5) through the address bus (19). Then, the data that has been subjected to predetermined rearrangement and decoding such as error correction is supplied from the memory (5) to the data bus (4). The data on this data bus (4) is the DA conversion circuit (20).
To the analog voice signal, and this signal is IO
It is taken out to the output terminal (21) through the circuit (2). 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). Taken out to the terminal (24). Further, the data from the operating device or the like is supplied to the control circuit (26) through the terminal (25), the data from the circuit (26) is supplied to the data bus (4), and the control signal from the circuit (26) is supplied. Are supplied to the memory (5) through the auxiliary bus (27). In addition, between the modulation circuit (8) and the recording amplifier (9) and the reproduction amplifier.
Between the (13) and the demodulation circuit (14), the changeover switch (28)
(29) is provided, the modulation circuit (8) and the demodulation circuit (14) are connected to the movable contact, the recording amplifier (9) and the reproduction amplifier (13) are connected to one fixed contact, and the other fixed contact is connected. Connected to each other. And this changeover switch (28) (29) is the control circuit.
By the control signal from (26), it is switched to the other fixed contact side in the EE mode. Further, FIG. 3 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 the field [1], and the recording heads (10A) (10B) Will be recorded at. On the other hand, B is a reproducing operation, and 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. Decoded in the first half of [-1], and then the next field

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

To extract the signal at [0], the reproducing heads (36A) (36B) should be
It is necessary to precede 0A and 10B by 3 fields or more. And in the case of the above device, the reproducing head (36A)
The mounting position of the (36B) on the rotating drum is the recording head (10A) (1
Since it is preceded by 120 degrees with respect to (0B), the actual preceding amount is It is a field. Further, FIG. 4 shows a time chart of the confirmation reproduction and the operation in the EE mode. In this figure, first, A is an operation of confirmation reproduction, and for example, in this field

A during the period [0]
The D-converted signal is encoded in the first half of the next field [1], time-axis-compressed in the latter half of this field [1], and output continuously, and is recorded by the recording heads (10A) and (10B). This recorded signal is reproduced by the confirmation reproducing heads (34A) (34B) in the first half of the next field [2]. Then, the reproduced signal is decoded from the latter half of the field [2] to the first half of the next field [3], and is time-axis expanded and read during the period corresponding to the subsequent one field, and DA-converted. That is, in this case, since the audio need not be synchronized with the video in the confirmation reproduction, the reading and the DA conversion are immediately performed. On the other hand, B in the figure is the operation in the EE mode,

The signal AD-converted in the period of [0] is encoded in the first half of the next field [1] and is time-axis compressed and read in the latter half of this field [1]. The read signal is supplied to the modulation circuit (8) and further supplied to the demodulation circuit (14) through the changeover switches (28) and (29). This demodulated signal is written again in the memory (5) and decoded in the next field [2]. Then, the decoded signal is time-axis expanded during the period corresponding to the following one field, is read, and is DA-converted. At this time, the memory (so that the timings of reading and DA-convert coincide with those in the above-described confirmation reproduction). The reading of 5) is controlled. Thus, according to the above-described device, the confirmation reproduction and the EE mode can be performed with a simple configuration, and the comparison of the signals can be performed well by matching the time points of these signals. It should be noted that the capacity of the memory (5) needs to be increased by one field when performing the confirmation reproduction and the EE mode. The arrangement of the heads on the rotating drum is not limited to the above example. [Effects of the Invention] According to the present invention, it is possible to obtain a signal that has been confirmed and reproduced and an EE mode signal, and to compare the two signals satisfactorily by matching the time points of these signals. Became.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of the present invention, FIGS. 2 to 4 are diagrams for explaining the same, and FIG. 5 is a diagram for explaining a conventional technique. (1) is an input terminal, (2) is an IO circuit, (3) is an AD conversion circuit,
(4) (6) (15) (16) is data bus, (5) is memory, (7) is encoder, (8) is modulation circuit, (9) is recording amplifier, (10) is recording head, ( 11) is a magnetic tape, (12) is a reproducing head, (13) is a reproducing amplifier, (14) is a demodulating circuit, (17) and (18) are decoders, and (1
9) is an address bus, (20) is a DA converter circuit, (21) is an output terminal, (22) is a digital input terminal, (23) is a digital IO circuit, (24) is a digital output terminal, and (25) is a terminal. , (26) are control circuits, (27) is an auxiliary bus, and (28) and (29) are changeover switches.

Claims (1)

[Claims] 1. A rotary drum provided with a first head for recording a video period of a video signal and a second head for recording a period other than the video period, and a peripheral surface of the rotary drum. A video tape recorder in which recording is performed by the first head and recording by the second head on each portion of the magnetic tape that is diagonally transported and is divided into two in the width direction. In the above, in the head corresponding to the second head, the audio signal is AD
In the case where recording processing including conversion and time axis compression is performed and supplied for recording, a third head is provided at a position following the head corresponding to the second head on the rotary drum. The reproduction signal from the head No. 3 is subjected to reproduction processing including time axis expansion and DA conversion corresponding to the recording processing to obtain a first reproduction audio signal, and the recording processed signal is directly supplied to the reproduction processing system. A video tape recorder adapted to obtain a second reproduced audio signal by controlling driving of a memory used for the recording / reproducing process so that the time points of the first and second reproduced audio signals coincide with each other.