JPH03144966A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To execute dubbing at high speed by compressing/extending the time base of encoded data at normal recording/reproducing time and setting the feed speed of a magnetic tape at the time of dubbing faster than that at the time of recording. CONSTITUTION:A time compression circuit 23 is provided for a recording system and it compresses the time base of encoded data in 1/n. Then, compressed data is recorded in the magnetic tape 3 by one of a pair of magnetic heads 1a and 1b. A time extension circuit 24 is provided for a reproduction system, and it extends a reproduced time base to n-times. At the time of dubbing, a mechanism control means 4 sets the feed speed of the tape 3 in a master deck and a slave deck at the time of dubbing to be n-times as much as that at normal recording time in the recording system. Then, data reproduced in the magnetic heads 1a and 1b are recorded into a slave tape at the same speed as the master tape. Thus, dubbing is attained at high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording and reproducing apparatus that records digital information such as video and audio on a magnetic tape or the like using a helical scan method.

(Prior Art) FIG. 3 shows a conventional magnetic recording/reproducing apparatus disclosed in, for example, Japanese Unexamined Patent Publication No. 80-133573 (la).

(lb) is a magnetic head, (2) is a rotating drum, and the magnetic heads (la) and (lb) are mounted so as to be spaced from each other by 180 degrees. (3) is magnetic tape,
(4) is a mechanism control circuit, which controls the rotation speed of the rotating drum (2) and the feeding of the magnetic tape (3);
) is a recorded video signal, (6) is a low-pass filter (hereinafter referred to as rLPFJ), which limits the band for sampling the input recorded video signal, and (7) is an A/D converter, which limits the band Sample the limited recorded video signal. (8
) is an encoder that encodes digitized recorded video data so that errors that occur when it is magnetically recorded and reproduced can be corrected. (9) is a modulator which further records and encodes the encoded recorded video data so that it becomes data optimal for magnetic recording and reproduction. (10) is a head amplifier that amplifies the recorded video data signal during recording and amplifies the magnetic head (la
) and (1b). (11) is a playback head amplifier, which is used for magnetic heads (1a) and (1) during playback.
The reproduced signal reproduced in step b) is amplified. (12) is a demodulator, which performs recording and decoding of the reproduced signal in the reverse method of recording and encoding in the modulator (9). (13) is a decoder, which performs error correction and detection of recorded and decoded data. Do this. (14) is a D/A converter which converts the reproduced video data whose errors have been corrected by the decoder (13) into analog data.

(15) is an LPF that limits the reproduced video signal to the video signal band. (16) is a reproduced video signal, (17) is a switching signal for switching the magnetic recording and reproducing device between self-recording and reproducing mode and dubbing mode, (18) is a dubbing input signal, (19)
is a dubbing output signal, (20) is a self-recording/dubbing changeover switch (hereinafter referred to as a "changeover switch"), and the input to the modulator (9) is connected to the output of the encoder (8) and the dubbing input signal (18). is switched by the switching signal (17) &: and inputted to the modulator (9). (21) is a synchronization signal input from an external device to the mechanism control circuit (4), and is used to synchronize with the external device.

(22) is an external synchronization signal, which is output from the mechanism control circuit (4) using a reference signal for rotational drum rotation speed control and tape feed control as a synchronization signal.

FIG. 4 is a data diagram showing an example of the error correction encoder (13), in which D (1,1), D (1,2), D (
2,1)D (2,2) -...D C8,1) ,
D (8,2) is information data, C(1,1) C(
1,2) C(1,3), C(2,1)C
(2,2), C(2,3) -...C(9,1
), C(9,2)C(9,3) is error detection data, P)l(1,3), P□(2,3)=P)l
(9,3) is horizontal parity data, Pv(9,1).

Pv(9,2) is vertical parity data.

's5 diagram is'! Of the data shown in Figure J4, it shows the data in which an error has occurred, (21) is the second of D (2, 1), (22) is the fifth of D (2, 1), (23)
is the fifth of D (2,2), (24) is D (8,1)
5th and (25) respectively indicate the 5th incorrect data of PH (6, 3).

FIG. 6 shows data whose errors were not corrected by the decoder (13) when the error data shown in FIG. 5 occurred.

Figure 's7 is a connection diagram when dubbing is performed using two conventional magnetic recording and reproducing devices, where (30a) is the master magnetic recording and reproducing device (hereinafter referred to as "master deck"), and (30b) is the slave. Magnetic recording and reproducing device (hereinafter referred to as
(referred to as "slave deck").

Next, the operation will be explained.

In the normal self-recording/playback mode, as shown in Figure 3, first, the recorded video signal (5) is passed through the LPF (6) to limit the band of the video signal, and the A/D converter (A) converts the video signal. Sample at a frequency that is more than twice the band. Generally, taking the NTSC system as an example, the video signal band is approximately 4.5MHz,
Considering Nyquist's theorem, it is necessary to sample at a frequency of 9 MHz or higher. Also, since the color signal is transmitted by quadrature two-phase modulation on a 3.58 MHz carrier wave, the sampling frequency is set to an integral multiple of 3.58 MHz in consideration of beat interference with the sampling frequency. is normal. From these relationships, the sampling frequency is 3·f, (f
, , means carrier frequency 3.58MHz, 3-f,
c is approximately 10.7 MHz) and 4 fsa (approximately 14
．． The digitized recorded video data, which is often set at 3MHz), is encoded by an encoder (8) so that errors that occur during magnetic recording and reproduction can be corrected, and then sent to the changeover switch (20). . Here, select the changeover switch (
20) is in self-recording/reproduction mode, the switching signal (17)
) by the self-recording and playback side, that is, the code! I (8) side is connected. Therefore, the encoded data is recorded and encoded by the modulator (9) so that it becomes optimal data for magnetic recording and reproduction. This encoding method includes NRZ, NRZI
There are methods such as The modulated recorded video data is amplified by a recording head amplifier (lO), and is then amplified by a magnetic head (la).
, <lb) is recorded on the magnetic tape (3).The mechanism control circuit (4) controls the number of rotations of the rotating drum (2) at a constant speed, and sends the magnetic tape (3) at a constant speed. Since it is controlled, helical scanning is recorded.

During reproduction, the signals reproduced by the magnetic heads (la) and (lb) are amplified by the reproduction head amplifier (11),
The demodulator (12) performs recording and decoding, and the decoder (13)
Error correction and error detection are performed on the reproduced data.

The data subjected to this error correction/detection is converted into analog data by the D/A converter (14) &:, and L P F (1
5), the band is limited and a reproduced video signal (16) is obtained.

Here, sign! (8) and the error correction method by the decoder (13) will be explained with reference to Figures 4 to 6. The encoder (8) is an A/D converter (7) that converts the digitized information data D(m, n)e into lone detection data C(m, n), which is redundant data for error detection. m and n are integers O satisfying 1≦m≦8.1≦n≦2
The same applies hereafter).

Horizontal parity P. (1,3) is composed of the parities of D (1,1) and D (1,2), and D(1,
The parity between the first data of 1) and the first data of D (1, 2) is P, (1, 3), and in the same way, P, (m, 3). ) is D (m, 1
) and D (1m, 2), and C(m
, 3) is the error detection data of P, (a, 3). The vertical parity Pv(9,1) is D(1,1), D
(2,1)...D (8,1) parity, and the first data of P V (9,1) is D (1
, 1), D (2, 1)...D (8°1), respectively, and Pv(9,
2) is 'D (1,2), D (2,2)...
- It is similarly configured with a parity of D (8, 2).

Also, P, (9,3) is PV(9,1) and Pv(9,2
) parity, C(9,1), C(9,2)C(9
, 3) are P v (9, 1) and P v (9, 2), respectively.
).

P, (9, 3) error detection data. Note that in this example, D (m, n), P M (11, 3),
P v (9, n) is composed of 6 bits each, and C(
m, n) are composed of 2 bits.

As shown in FIG. 5, the reproduced data D (2,1)D (2,
2), D(6,1), and PM(8,3), the reproduced D(2)
,1) Creating horizontal parity from D (2,2), we get
Since the 2nd bit (21) of D (2, 1) is incorrect, the z-th bit of the created horizontal parity is P, (2, 3).
It is different from the 2nd bit. However, 5b of D (2,1)
Itth bit (22) and 5th bit (23) of D (2,2)
are both wrong, so the created horizontal parity and P,
The 5th bit of (2, 3) becomes equal. In this way, from the error detection results of D (2,1) and D (2°2), P, (2,3), and the created horizontal parity,
Only error (21) is corrected. Similarly, D(6,1)
An error (24) is detected in D (6,2), and no error is detected in D (6,2). Therefore, when horizontal parity is created from the reproduced D (6, 1) and D (6, 2), the 5th bit is different from the original P, (6, 3). However, since the 5th bit (25) of P, (6, 3) is also incorrect, the error (24) is not corrected.

Next, the regenerated D (1,1), D (2,1)
When vertical parity is created from D (3,1), -...D (8,1), errors (22) and (24) become
Since both are the 5th bit, they are the same as the 5th data of Pv(9,1) and cannot be corrected.

Next, the regenerated D (1,2), D (2,2)
When vertical parity is created from D (3,2), . . . D (8,2), the fifth data differs from the fifth data of Pv(9,2) due to error (23). Due to this result and the error detection result of D (2, 2), the error (23)
will be corrected. Error (25) is also corrected in the same way, but errors (22) and (24) are corrected as shown in FIG.
It remains uncorrected.

Next, a case where dubbing is performed using this magnetic recording/reproducing device will be explained. In FIG. 7, (2b) to (22b) of the slave deck (30b) are the same parts as (2) to (22) of the master deck (30a), respectively, and the dubbing output signal (
19) is input to the dubbing side terminal of the changeover switch (20b) as the dubbing input signal (tab) of the slave deck (30b), and the external synchronization signal (22) is input as the synchronization signal (21b) to the mechanism control circuit (4b). is entered as .

Next, the operation will be explained.

First, from the master tape (3) mounted on the master deck (30a), the magnetic heads (la), (lb)
The recorded video data is played back, demodulated by the demodulator (12), and then subjected to error correction and detection by the decoder (13), and sent to the slave deck (30b) in the form of digital video data as a dubbing output signal (19). Sent. The slave deck (30b) records and encodes the sent digital video data again using the modulator (9b) and records it on the magnetic tape (3b), thereby enabling dubbing.

Here, for example, errors (21) to (25) as shown in FIG. 5 occur when playing the master tape (3), and the decoder (1)
3), the error (21
), (23) and (25) have been corrected and the error (2
2) and (24) are not corrected, the slave tape (3b) e is dubbed, and the slave tape (3b)
), errors (22) and (24) occur in the decoder of the slave deck (30b). is detected, and the horizontal parity created from the reproduced D (2,1) and D (2,2) and P□(2
, 3) is different from the fifth data. Therefore, D (
Error detection result of 2゜1) and reproduced D (2,1)
! Error (22) can be corrected from nine horizontal parity created from 5 and D (2, 2) and P, (2, 3), and error (24) can also be corrected in the same way.

As mentioned above, when editing or dubbing, assuming that no new errors occur after the second generation date, the transition will be made to the second and third generation scenes (therefore, corrections will be made on horizontal parity and vertical parity). Correction is repeated, and the errors occurring in the first generation continue to decrease to a predetermined error rate.However, in reality, as the transition progresses, new errors occur each time, so the error rate decreases. The degree becomes smaller.

Furthermore, in recording and reproducing video signals such as self-recording and dubbing, the video signals are generally processed in blocks such as fields or frames, and recorded on tracks on a magnetic tape in blocks.

[Problem to be solved by the invention]

Since the conventional magnetic recording/reproducing apparatus is constructed as described above, dubbing can only be performed at normal recording or reproducing speeds, and there is a problem in that dubbing C takes a long time.

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a magnetic recording/reproducing device that can perform dubbing at high speed.

[Means to solve the problem]

The magnetic recording and reproducing apparatus according to the present invention includes means for compressing the time axis of encoded data to 1/n in the recording system, records on a magnetic tape with one magnetic head, and has a reproducing system with a means for compressing the time axis of encoded data to 1/n. The time axis of data reproduced by two magnetic heads is n
It also has a mechanism control means for increasing the magnetic tape feeding speed of the magnetic recording and reproducing devices serving as master deck and slave deck by n times during dubbing, and when dubbing, the recording system A pair of magnetic heads reproduces data from a master tape recorded with the axis compressed to 1/n at n times the tape speed, and this data is transferred to the master tape by a pair of magnetic heads on a slave deck. It is characterized by recording on slave tapes at the same feed speed.

(Function) The magnetic recording and reproducing apparatus according to the present invention records data compressed by 17 n &: on the time axis for one cycle using one magnetic head during recording, and records data compressed by 17 n The time axis of the reproduced data is expanded n times and returned to a continuous data string.

Also, during dubbing, the master tape recorded with the above recording system is fed by the master deck at n times the tape speed and reproduced by a pair of magnetic heads, and this reproduced data is transmitted to the same pair of magnetic heads of the slave deck. It is configured to record on a slave tape at a certain feed speed.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. N1
In the figure, parts that are the same as those in Figure 3 are given the same reference numerals and their explanations are omitted. Compress the time axis.

(24) is a time expansion circuit which expands the time axis of the decoded video signal data block by block at a ratio opposite to the time axis compression ratio in the time compression circuit (23).

FIG. 2 (^) is a diagram showing the scanning pattern of the magnetic head during self-recording and reproducing, and (25) shows the track on which the magnetic head (la) scans and records/reproduces during the first rotation of the rotating drum (2); (Zo is a track scanned by the magnetic head (1b) but not recorded or reproduced; (27) is a track scanned by the magnetic head (la) during the second rotation of the rotating drum (2) and recorded or reproduced; (28) is also a magnetic head (l
Track b) is a track that is scanned but not recorded or reproduced.

Figure 2 (B) is a diagram showing the scanning pattern of the magnetic head during dubbing, and (29) is one of the rotating drums (2).
The track (30) is the track on which the magnetic head (1a) scans and records/reproduces at the rotation, the track (30) is also the track on which the magnetic head (1b) scans and records/reproduces, and (31) is the rotating drum (2).
The track (32) is the track on which the magnetic head (la) scans and records/reproduces during the second rotation of the magnetic head (1b).

Next, the operation will be explained. During self-recording and playback, the rotating drum (2) receives one of the video signals by the mechanism control circuit (4).
It is controlled to rotate twice in one frame period. Therefore, the tracks scanned by the magnetic heads (la) and (lb) are as shown in FIG. is divided into blocks by a time compression circuit (23), for example, in units of fields of the video signal, and the time axis is further compressed to 1/2 or less for each block. This block data is encoded by an encoder (8) to add error detection data D, horizontal parity data P M , and vertical parity data Pv shown in the figure 's4. The signal is recorded and encoded by the modulator (9).

This recorded block data is an intermittent signal, and is sent to the magnetic head (LA) via the recording head amplifier.
The track (25) shown in solid line in Figure 2 (^),
(27)... is recorded. In this case, the magnetic head (
Since no signal is applied to 1b), data for one frame of the video signal is recorded on two tracks (25) and (27) in two rotations of the rotating drum (2). During playback, the magnetic head (1a) tracks (25) at the same tape speed and rotating drum speed as during recording.
), (27)-... are scanned and played back, and the head amplifier (
11), and is recorded and decoded by a demodulator (12) as in the conventional example. This demodulated data is sent to the decoder (
13), error correction and detection of the reproduced data is performed based on the error detection data, horizontal parity, and vertical parity. Since this decoded playback data is an intermittent signal for each block, it is time-expanded by the time expansion circuit (24) at a ratio opposite to the time compression ratio applied during recording, and becomes the original continuous video signal. data, and the D/Ai converter (1
4), the signal is converted into an analog signal, and the signal is band-limited by an LPF (15) to become a reproduced video signal (18).

Next, the operation during dubbing will be explained. As shown in FIG. 7, the connection between the master deck (30a) and the slave deck (30b) is the same as in the conventional example.

Next, the mechanism control circuits (4), (4b) of both decks (30a), (30b) control the rotating drums (2),
A switching signal (17) that controls the rotation of (2b) to rotate twice in one frame period of the video signal and instructs a dubbing mode.

Following (17b), magnetic tape (3), (3b)
Control the feed speed to double speed. Therefore, the track pattern in which the magnetic heads (la) and (xb) scan the magnetic tape (3) serving as the master tape is as shown in FIG. 2 (B), and during one frame period of the video signal, Both rotating drums (2) and (2b) rotate twice, and in the first rotation, the magnetic head (la) scans the track (29), and the magnetic head (lb) scans the track (30), and in the second rotation, the magnetic head (la) scans the track (30), and in the second rotation, Since the head (la) scans the track (31) and the magnetic head (lb) scans the track (32), the reproduced signal is composed of reproduced data (continuous block data) (
19), the master deck (30a) demodulates this reproduced data (19) with a demodulator (12), and outputs the reproduced data (19) to the decoder (19).
After decoding in step 3), the video signal data with its time axis compressed is transferred to the slave deck (30b). In the slave deck (30b), the input playback data (1
9) is recorded and encoded by the modulator (9b), and the magnetic head (l
a) Master deck (30a) by (lb)
Recording is performed on two tracks for each rotation of the rotary drum (2b) by track scanning similar to the above. Therefore, since block data is continuously reproduced and recorded, dubbing can be performed at twice the data rate of self-recording and reproducing.

The magnetic tape (3
In playback (b), the tape is recorded at twice the speed and played back at 1x speed, so there will be a deviation in the slope of the recorded track compared to the master tape. It can be fully reproduced by performing tracking servo.

In the above embodiment, the time axis of block data is 17
Two companies compressed data, recorded it on magnetic tape, doubled the time axis of the playback data, doubled the magnetic tape feeding speed during dubbing, and compressed the time axis to 1/2. The head reproduces the signal as a continuous signal, and a pair of magnetic heads records the data in the same track pattern as the master tape. However, in a device that records data for one field period on zero tracks, The time axis compression rate may be set to 1/n, the time axis expansion rate may be set to n times, and the tape feeding speed during dubbing may be set to n times.

Further, in the above embodiments, the explanation has been given using a video signal as an example, but the present invention can be similarly applied to an audio signal, or any other signal having periodicity, as long as it performs helical scan recording.

(Effect of the invention) As described above, according to this invention, the time axis of data is
/ n and is recorded by helical scanning on a magnetic tape with one magnetic head, and when playing back, the time axis of the data reproduced with one magnetic head is expanded by n times and decoded to the original continuous data. Furthermore, when dubbing, the master tape recorded with the above recording system is
We reproduced data using a pair of magnetic heads at twice the tape feed speed, and recorded the same track pattern as the master tape using a pair of magnetic heads on a slave deck with the same tape feed speed. This has the effect of providing a magnetic recording/reproducing device capable of high-speed dubbing.

[Brief explanation of the drawing]

Fig. 1 is a block circuit diagram of an embodiment of the present invention, Fig. 2 (^) is a diagram showing the scanning pattern of the magnetic head during self-recording and reproducing of this embodiment, and Fig. 2 (B) is a diagram of this embodiment. A diagram showing a scanning pattern of a magnetic head during dubbing,
3 is a block circuit diagram of a conventional magnetic recording/reproducing device, FIG. 4 is a diagram showing the data structure of this conventional example, and FIG. 345 is a diagram showing information data in which an error has occurred among the information data in FIG. FIG. 6 is a diagram showing information data whose errors have not been corrected by the decoder, and FIG. 7 is a diagram showing the connection of two magnetic recording and reproducing apparatuses during dubbing. (la), (lb)-magnetic head, (2), (
2b) ...Rotating drum, (3) , (ab)...
-Magnetic tape, (4), (4b)...mechanism control circuit (a)...A/D'JR converter, (8)...encoder, (9). (9b)...Modulator, (12)...Demodulator, (13
)...decoder, (14)...D/A converter, (23
〉...Time compression circuit, (24)...Time expansion circuit,
(30a)...Master deck, (3b)--Slave deck. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) Data encoded with periodic information is helically scanned by a pair of magnetic heads arranged with a phase difference of 180° on a rotating drum, and n pieces of data corresponding to one cycle of the above information are recorded on a magnetic tape. In a magnetic recording and reproducing apparatus configured to record data on a track and decode the data reproduced by the pair of magnetic heads during reproduction, the time axis of the encoded data provided in the recording system is 1/n
a means for compressing the compressed data onto a magnetic tape with one of the magnetic heads of the pair of heads, and a means for expanding the time axis of the reproduced data provided in the reproduction system by n times. and a mechanism control means for increasing the feeding speed of the magnetic tape of the master deck and the slave deck by n times the speed during recording in the recording system during dubbing, and the mechanism control means for increasing the feeding speed of the magnetic tape of the master deck and the slave deck by n times the speed during recording in the recording system, when dubbing, from the master tape recorded in the recording system to the master tape. A magnetic recording and reproducing device characterized in that data reproduced by a pair of magnetic heads on a deck is recorded on a slave tape having the same feed speed as the master tape using a pair of magnetic heads on a slave deck.