JPS6020362A - Magnetic recording device - Google Patents

Abstract

PURPOSE:To improve the ability to correct an error of an audio PCM signal during reproduction by recording the audio PCM signal partially on two auxiliary parallel tracks which adjoin to an end part of video tracks in vertical blanking periods of a video signal. CONSTITUTION:A magnetic tape is wound around circumferential surfaces of an upper and a lower drum which are arranged coaxially; a video head 4A form slanting video tracks, and sink heads 4B and 4C as auxiliary heads form slanting sink tracks which are parallel to each other. A color video signal supplied to an input terminal 21 is FM-modulated 23 and supplied to the head 4A. Audio signals supplied to input terminals 22A and 22B are passed through a sound recording data processing circuit 28 and a time-axis compressing circuit 32 to distribute the audio PCM signal to the heads 4B and 4C in vertical blanking periods of the video signal. Thus, the signals are recorded to compose reproduced data of signals on both tracks during reproduction, improving the ability to correct an error.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a magnetic recording device that records a video signal and an audio PCM signal related to the video signal using a rotary head.

"Background Art and its Problems" In order to improve the quality of audio signals, it has been considered to record audio PCM signals together with video signals on magnetic tape using a rotating head.

The audio PCM signal is recorded, for example, in a separate track near the end of the video track. This is an existing C
This is advantageous in that a 1-inch helical scan VTR can be used as is, and it also facilitates editing of audio signals alone.

However, the rotary head type recording device has a problem in that the error rate of the reproduced audio PCM signal becomes high due to instability of the contact and separation positions of the rotary head and the magnetic tape at the end of the track. Therefore, the audio PCM signal to be recorded is subjected to error correction encoding with high correction ability. As a result, redundancy increases and the error correction code encoder becomes complicated.

``Object of the Invention'' The object of the present invention is to provide a magnetic coin-writing device that can further improve the error correction ability of audio PCM signals and the error correction ability.

``Summary of the Invention J This invention has a rotating auxiliary head that forms two parallel auxiliary tracks proximate to the ends of the video tracks within the vertical blanking period of the video signal; In this system, audio PCM signals are distributed to tracks and recorded.

Embodiment A VTR in an embodiment of the present invention has a head arrangement shown in FIGS. 1A and 1B. In FIG. 1, 1 indicates an upper drum, and 2 indicates a lower drum. The upper drum 1 and the lower drum 2 are arranged coaxially, and the upper drum 1
is the field frequency (60 in NTSC system) in the direction of arrow a.
Hz).

As shown by the two-dotted chain line in FIG.
It runs at a speed of L/sec.

The upper drum 1 is provided with three sets each consisting of a video head as a main head and a sync head as an auxiliary head. 4A is a video head for recording and playback;
4B and 4C are sync heads for recording and reproduction, and 5
A is an erasing head for the video signal track, and 5B and 5C are erasing heads for the sync signal track. Video head 4A and sink head 4B
.

Erasing heads 5A, 5B, and 5C are provided at positions preceding 4C in the rotational direction of the upper drum 1. Also, assembling the video head 4A and sync head 4B,
A reproduction-only video head 6A and sync heads 6B and 6C are provided at positions delayed with respect to the rotational direction of the upper drum 10.

These video heads 4A, 5A, 6A and sync heads 4B, 5B, 6B are arranged with the sync head in front by an angular interval of 30 degrees, and their heights are slightly different. There is. Furthermore, the playback-only video head 6A is attached to one end of the support plate of the piezoelectric element, and its height can be varied by an external control signal, so that the scanning locus of these heads can be adjusted even in non-normal playback operations. is matched with the video signal track. The video heads 4A, 5A, 6A are arranged at angular intervals of 120° from each other.

FIG. 2 shows a recorded putter 7 (
7) Indicates 7-ohm. Audio tracks 10A and 10B are formed in parallel along the upper edge of the magnetic tape 3, and an audio track 11 is formed along the lower edge of the magnetic tape 3.

Audio signals and time codes are recorded in the audio tracks 10A, 10B, and 11, respectively. Further, a control track 12 is formed in parallel above the lower audio track 11, and a servo control signal is recorded on this control track 12. A diagonal video signal track 13 is formed in the central region between the audio trunk 10A and the control track 12, and a diagonal sync signal track 14B is formed in the region between the audio track 11 and the control track 12.
and 14C are formed. The video signal track 13 and the sync signal trunks 14B and 14C are formed by the video head 4A and the sync heads 4B and 4C.

The sync signal tracks 14B and 14C are parallel to each other.

When no audio PCM signal is recorded, the sync signal track 14B contains the vertical sync signal section and the following 10
A signal of a vertical blanking period of (number) (() f is one horizontal interval) is recorded. Furthermore, the signals recorded at both ends of the sync signal track 14B and the signals recorded at the end and start ends of the video signal tracks located before and after the sync signal track 14B overlap, and this overlap section is The center is the switching point for switching heads during playback. FIG. 3 shows this switching point. 1st field or 3rd field of color video signal
In the field, the playback output of the video head is switched to the playback output of the sync head at a timing slightly after the center of the 3rd horizontal section, and the playback output of the sync head is switched at the beginning of the 17th horizontal section. A switch is made from to the playback output of the video head. In the second or fourth field of the color video signal, the playback output of the video head is switched to the playback output of the sync head at the beginning of the 266th horizontal section, and the switch is made from the playback output of the sync head at the end of the 278th horizontal section. The playback output is switched from the playback output of the video head to the playback output of the video head.

The head arrangement and recording pattern described above are the same as those in the existing C-format 1-inch helical scan VTR. In one embodiment of the present invention, audio PCM signals subjected to error correction encoding processing and time-base compressed are distributed and recorded on the sync signal tracks 14B and 14C.

FIG. 4 shows an enlarged view of the sync signal tracks 14B and 14C. Also, in Figure 4, 2
The sync signal track 14 shown by the dashed dotted line is in the existing C-format 1-inch helipscan VTR. This sync signal track 14 has a head width of Dt and a guard width of D2. In this embodiment, the head width of the 7-ink heads 4B and 4C is Dh
As shown in , the sink head 4 is made thinner and the sink head 4 is
The center of the sync signal track 14B formed by B coincides with the center of the sync signal track 14, and
The center of the sync signal trunk 14C formed by the sync head 4C is made to coincide with the center of the guard node.

As an example, Dt=130 μm, Dg-52 μm].

D -50 μm. When an audio PCM signal is not recorded, a recording pattern compatible with the C format can be formed by recording part of the signal during the vertical blanking period only on the sync signal track 14B.

FIG. 5 shows the configuration of a recording circuit according to an embodiment of the present invention, in which a recorded color video signal is supplied to an input terminal indicated by 21, and two channels of recorded audio signals are supplied to each of input terminals indicated by 22A and 22B. Supplied. The color video signal is p-FM modulated by the FM modulation circuit 23 and supplied to the ° gate circuit 24 . A gate pulse (not shown) is supplied to the gate circuit 24, and the gate circuit 24 is turned on for a period corresponding to the video signal track 13. The output of this gate circuit 24 is supplied to the video head 4A via a recording amplifier 25 and a rotary transformer (not shown), and is recorded on the magnetic tape 3.

It's a moat, the audio signal is Aro converter 27A and 27
For example, an audio PC with 14 bits per sample at a sampling frequency of 44.0559 kHz.
It is converted into an M signal and supplied to the recording data processing circuit 28. The clock pulses and timing control signals for processing the audio PCM signal are synchronized with the color video signal synchronization signal. clock generator 2
9 is supplied with a horizontal synchronization signal separated from the color video signal by a synchronization separation circuit 30, and a master clock having a horizontal frequency fH 1344 times (=21.'146832 MHz) is formed. Similarly, a horizontal synchronization signal is supplied to the timing control circuit 31 to form a pulse at the sampling frequency, which is then applied to the recording data processing circuit 282, the time axis compression circuit 32, the preamplifier and synchronization generation circuit 33. Timing control signals required by each of the digital modulation circuits 35B and 35C are formed.

The recorded data processing circuit 28 encodes the two-channel audio PCM signal with an error correction code to generate recorded audio data in a predetermined format. 6th
The figure shows the structure of recorded audio data in an embodiment of the present invention.

This audio data has a structure in which the unit is IH (-1/fH), similar to the synchronization signal of the video signal. A 4-bit synchronization signal 40 is added to the beginning of the IH, followed by 14-bit sampling words (3 words for each channel, A and B), followed by two parity words of an error correction code. P, Q (14 bits each)
are arranged, and furthermore, a sampling word and a parity word P,
CRC code (16 bits) for error detection for Q
is added, and a white reference signal 41 is inserted at the end.

Therefore, 1 block (12 bits) is stored in IH (168 bits).
8 bit) data is inserted.

Furthermore, since audio data is inserted into the 245H section within 1 2 (1 field), 735 samples of data are included in the IV.

The error correction code forms a simple parity word P and a more complex harness word Q from 6 words of data within one block, and has the ability to correct up to 2 word errors within the same block. Furthermore, the 6 sampling words and 2 parity words of one block are converted into IH yearly data through an interleaving process in which the arrangement order is different from the original arrangement order.

Note that the block synchronization signal 40 and the white reference signal 41 may not be inserted.

Recorded audio data from the recorded data processing circuit 28 is supplied to a time axis compression circuit 32. Time axis compression circuit 32
is composed of a RAM (random access memory) having four banks, and performs compression processing on the IV yearly time axis, and also supports two channels: one consisting of odd-numbered blocks and one consisting of even-numbered blocks. Perform the distribution. FIG. 7A shows the time axis of the video signal, and Ts is sync head 4B, 4 in 1.
C shows an interval in which audio data is recorded within an interval in which a recording signal is supplied. Ts is 12H from the fourth horizontal section in the first or third field.
The length of the degree and the length of the degree 12 (degrees) from the center of the 266th horizontal section in the second or fourth field are selected.

As shown in FIG. 7B, recording audio data is written alternately in block units to the two banks of the RAM starting from the beginning of 1. This writing is done by a write clock that is synchronized with the recorded audio data. 1■
When writing of the data is completed, the contents of the two banks of the RAM are simultaneously read out as two channels of data by the high frequency read clock during the interval Ts. IV
The frequency ratio between the write clock and the read clock is determined by the length ratio between Ts and Ts. Furthermore, as shown in FIG. 7C, recording audio data is similarly written to the other pair of banks from the beginning of the next IV that includes the section Ts in which a pair of banks performs a read operation, and this 1. In the interval Ts immediately after the end of , the contents of the two banks are simultaneously read out as two channels of data.

The recorded audio data of each channel compressed by the time axis compression circuit 32 is supplied to addition circuits 34B and 34C, and a preamble signal and a synchronization signal are added thereto. The synchronization signal has a predetermined bit pattern that is added before the recorded audio data, and the preamble signal is added before the synchronization signal. The preamble signal is a signal that becomes a signal with a predetermined repetition frequency after digital modulation. Furthermore, a postamble signal may be added after the recorded audio data.

The outputs of adder circuits 34B and 34C are supplied to digital modulation circuits 35B and 35C. Digital modulation circuit 3
5B and 35C convert recorded audio data in order to improve recording density. The outputs of the digital modulation circuits 35B and 35C are connected to the switch circuit 3.
It is supplied to gate circuits 37B and 37C via 6B and 36C. Although not shown, gate pulses are supplied to these gate circuits 37B and 37C, and the gate circuits 3'7B and 37C are turned on in the sections where the sync signal tracks 14B and 14C are formed. . The outputs of the gate circuits 37B and 37C are sent to the recording amplifier 3.
It is supplied to sink heads 4B and 4C via 8B and 38C and a rotary transformer (not shown).

The output signal of the FM modulation circuit 23 is supplied to the other input terminal of the switch circuit 36B, and no signal is supplied to the other input terminal of the switch circuit 36C, and when an audio PCM signal is not recorded, A video signal is recorded as a sync signal track 14B.

Note that the 2
The analog audio signal of the channel is
Audio track 1 of magnetic tape 3 by fixed head
Recorded in 0A and IOB.

Next, a reproducing circuit according to an embodiment of the present invention will be described. During reproduction, a video head 6A supported by a piezoelectric element such that its height can be changed and a fixed sync head 4B, 4C are used.

As is clear from the head arrangement shown in FIG. 1, the video head 4A corresponds to the sync head 4B, so by using the video head 6A,
The scanning of the civiteo head 6A is delayed by 0' (-termination V) from the original scanning timing. Furthermore, by the cab's tongue servo circuit and dynamic tossicking control, the audio PCM signals reproduced by the sink heads 4B and 4C are made to precede the video signals reproduced by the video head 6A throughout the TV. This is to compensate for the delay in the audio signal of 1* caused by the time axis compression process of the recording circuit, and to secure 1* as the time required for the reproduction process.

Referring to FIG. 8, the playback output of video Hendro A and 7/
The processing for reproducing and outputting requests "4B and 4C" will be explained.

The reproduction output of the video head 6A is supplied to a switching and equalizer circuit 52 via a reproduction amplifier 51 and a rotary transformer (not shown).

On the other hand, the reproduction output of '/7 head 4B is
The signal is supplied to the switching and equalizer circuit 52 via a 3B2 rotary transformer (not shown) and one output terminal 55A of the switch circuit 54. The switching and equalizer circuit 52 switches the reproduction outputs of the video head 6A and the sync head 4B at a predetermined switching timing (see FIG. 3) to make the signals of the two continuous. This switching pulse is formed based on a detection pulse from a detection element that detects the rotation of the upper drum 1. The output of the switching and equalizer circuit 52 is supplied to an FM demodulation circuit 56, and a reproduced video signal is taken out at an output terminal 57.

The output of the playback amplifier 53B is supplied to the PCM equalizer 58B via the other output terminal 55B of the switch circuit 54, correcting the amplitude characteristics of the tape head system during recording and playback, and adjusting the eye pattern of the playback digital signal. It can be said. The output of the other sync head 4C is supplied to a PCM equalizer 58G via a reproduction amplifier 53C.

The outputs of the PCM equalizers 58B and 58C are supplied to comparators 59B and 59cK, their levels are compared at the zero-crossing point of the eye pattern, and the outputs are shaped into pulse signals.

The outputs of the comparators 59B and 59C are supplied to digital demodulation circuits 60B and 60C to perform channel coding.

The output of the PCM equalizer 58C is supplied to the RF detection circuit 61. The outputs of comparators 59B and 59C are supplied to clock generation circuits 63B and 63C. These clock generation circuits 63B and 63C have a PLL configuration and generate clocks synchronized with the output signals of comparators 59B and 59C. This clock is used as a write clock for each of time axis expansion circuits 64B and 64C.

The control voltage for VCOK of the clock generation circuit 63C is:
The signal is also supplied to a determination circuit 62, and it is detected whether or not the audio PCM signal is being stably reproduced from the magnetic tape using the control type 1i3 AC components. Further, the RF detection circuit 61 detects the level of the reproduced signal taken out as the output of the PCM equalizer 58C. The outputs of the RF detection circuit 61 and the discrimination circuit 62 are supplied to the synthesis circuit 71. A switch circuit 54 and a reproduction processing circuit 68, which will be described later, are controlled by the output of the digital synthesis circuit 71.

When the audio PCM signal is not recorded, the /link signal track 14C is not formed, and even if the audio PCM signal
Even if the signal is recorded, tracking cannot be achieved and an audio PCM signal of sufficient amplitude cannot be played back.
The output of the combining circuit 71 causes the switch circuit 54 to select the output terminal 55A. Also, audio PC
When the M signal is not recorded, or even if it is recorded, it is not reproduced well, the output of the synthesis circuit 71 mutes the output of the audio PCM signal from the reproduction processing circuit 68.

The output of the time axis expansion circuits 64B and 64C is the switch circuit 6
7. The switch circuit 67 is switched block by block based on the output of the clock generation circuit 65, and the switch circuit 67 obtains audio F'CM data consisting of consecutive blocks shown in FIG. 6, which is supplied to the reproduction processing circuit 68. The reproduction processing circuit 68 performs dinterleave and error correction processing. For sampled words whose errors cannot be corrected, the errors are corrected so that they are not noticeable. The two channels of reproduced analog audio PCM signals of this reproduction processing circuit 68 are supplied to converters 69A and 69B, and two channels of reproduced analog audio signals are taken out at output terminals 70A and 70B.

In one embodiment of the invention, audio signal track 10
Since analog audio signals are also recorded on A and IOB, the muting described above is performed and the audio signal track IOA is also recorded.

Alternatively, an analog audio signal reproduced from 10B may be used.

"Application example" When distributing an audio PCM signal to two channels,
The distribution is not limited to the unit of one block, but may be distributed in the unit of multiple blocks.

"Effects of the Invention" According to the present invention, since the audio PCM signal is divided into two channels and recorded on separate tracks, the playback data of both tracks can be synthesized during playback, and the error correction ability is improved. can be improved.

[Brief explanation of the drawing]

1A and 1B are a plan view and a side view showing the configuration of a head arrangement according to an embodiment of the present invention, FIG. 2 is a route diagram of a track pattern according to an embodiment of the present invention, and FIG. A waveform diagram used to explain the switching points for switching the playback outputs of the video head and the sync head, and FIG. 4 is an enlarged view of a portion of the track pattern of an embodiment of the present invention.
FIG. 5 is a block diagram of a recording circuit according to an embodiment of the present invention.
FIG. 6 is a route diagram showing the data structure of an audio PCM signal, FIG. 7 is a time chart used to explain the operation of the time axis compression circuit, and FIG. 8 is a block diagram of a reproduction circuit according to an embodiment of the present invention. 3...Magnetic tape, 4A, 6A...
...video head, 4B, 4C, 6B, 6C...
...Sink head, 5A, 5B, 5C...
・・・Erasing head, 13・・・・・・・・・・・・
Video signal track, 14B, 14C...
・Sync signal track, 21... Recording color video signal input terminal, 22A, 22B...
...Input terminal for recording audio signal, 32...
...Time axis compression circuit, 57...Output terminal for reproduced color video signal, 64B, 64C...Time axis expansion circuit, 68...Reproduction processing circuit ,7
0A, 70B... Output terminals for playback audio signals. Agent Tadashi Sugiura Figure 2 Figure 3 Date ELDi ORFIELD 3 FIELD20RFIELD4 Figure 6 7.1

Claims (1)

[Claims] In a magnetic recording device for recording a video signal and an audio PCM signal obtained by PCM modulating an audio signal related to the video signal on a magnetic recording medium, a rotating main head forming a track; a rotating auxiliary head forming two parallel auxiliary tracks close to an end of the video track within a vertical blanking period of a video signal; and a circuit for distributing and recording the audio PCM signal.