JPS623405A - Pcm recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve the recording density by providing the reproducing circuit to feed back the new recording information having an (N) number of channels in total to an encoder part and the selector to select the feed-back data and the external input data, at a PCM recording device in a helical scanning system. CONSTITUTION:When recording is newly executed to channels 1 and 2, the input from an A/D conversion device 8 is supplied through a selector 9 to a recording encoder 10, coding and interleaving are executed and the recording is executed. Thereafter, when the data of a channel 1 are rewritten only the selector 9 at the channel 2 side is operated, the data recorded earlier are read by the reproducing head, and by the channels 1 and 2 and a decoder, the error revision, deinterleaving and correction are executed. Consequently, when such a partial afterrecording is executed, the new recording is also executed for the adjoining track, and therefore, the undeleted part of the same azimuth does not occur. For such a reason, overlapped writing can be executed and the recording density is heightened.

Description

[Detailed description of the invention] [Industrial application field] This invention is for stereo recording, playback, and karaoke recording.

This invention relates to a PCM recording and reproducing device that records or reproduces multi-channel recording or recording using a rotating head, and in particular, the present invention proposes a means for increasing recording density in a helical scan method using a rotating head method. be.

[Conventional technology]

As a PCM recording device that uses magnetic tape as a recording medium,
Currently, two methods have been proposed: a fixed head method and a rotating head method.

Figure 2 (a) shows the two-channel rotary head in the conventional rotary head system described above, and (0) shows the helical scan tape recording pattern (track format) using this. A rotating cylinder C is provided to rotate in the same direction as the tape 22 (VIIs method) (in the opposite direction in the β method) with a constant tilt rotation relative to the running direction of the tape 22, and a pair of recording cylinders are mounted on the rotating cylinder. Play head A.

B are provided at positions facing each other in the diametrical direction, and the heads A,
1-channel and 2-channel signals are input to B, respectively. As a result, head A sequentially traces the trunk tl+j3... on the tape 22 shown in FIG. 2(b), and head B traces the same track t2. t4;...
・Trace sequentially. Then, when the recording density is increased, the adjacent trunks tl, t! In order to prevent crosstalk caused by..., the directions of the gap between heads A and B are somewhat inclined in opposite directions with respect to the running direction of the heads. This inclination angle is an azimuth angle, and for example, head A performs +azimuth recording, and head B performs -azimuth recording. This reduces the crosstalk noise level, making it possible to use the override method (overwriting) and achieve high-density recording.

In the case of this rotating head method, whether the playback head faithfully tracks the recording pattern depends on the track linearity of the system, and assuming a system in which this track linearity fluctuates by a maximum of ±β, The third example shows the head output at that time.
Figure 4. In FIG. 3, 1 indicates the head (the above-mentioned head A or B), and 2 indicates the trunk (the above-mentioned t+, tz, . . . ) to be traced by the head. or,
3 is a reference line for writing (recording) and reading/reproducing). At this time, assuming that head 1 is a head for +azimuth, and track 2 to be traced is always recorded in +azimuth, the tracks adjacent above and below to track 2 are both -azimuth as described above. This will be a record.

In addition, in the figure, C is the head width, b is the track pitch, and a is the length of the override part, which has a relationship of -b, and the length a is 1/10 of the head width C.
The width shall be . Further, the relationship between track linearity variation width ±β is assumed to be β=2a.

In Figure 3, (a) is the correct state (ON-wRtrE
) on the track where writing was performed in the correct state (O
This is a model for reading with N-READ). The state of the output of the head 1 at this time is shown in Figure 4.

At this time, the head 1 runs on the track on which 8bχ is to be read, and the other 20χ (2a) reads information on another track at one azimuth on both sides.

However, if the part recorded with -azimuth is read out with a +azimuth head, the output will drop considerably, so in Figure 4, the crosstalk (noise) level 5 is shown as half the width of output 4 read out with +azimuth. It is.

FIG. 3 (+1) shows the case where a track written at the correct position is read out with a deviation of one β (OFF READ). In this case, the readout efficiency is 70.chi., as shown by case 2 in FIG.

FIG. 3(C) shows the worst case where the writing and reading fluctuations are shifted in opposite directions by β.

The read efficiency in this case is 50.chi. as shown in FIG. 4 N3-1. By the way, in the case of a system that records continuously in the tape running direction, 11kL3-1
As shown in the figure, since the output of the later 50χ head is one azimuth output, the noise level 5 usually does not increase much.

[Problem that the invention seeks to solve]

However, in a system that uses a discontinuous recording method in the tape running direction, there is unerased information from the previous recorded data, and since this unerased data is recorded in the same azimuth, the noise level at the time of reading is This will cause major deterioration. If the previous recording was recorded at the correct position and the tracking shown in FIG. 3(C) was performed, this noise would result in an output 6 as shown in FIG. 4 N13-2. In other words, output 6 is the unerased +azimuth information, which is 2 here.
Close 0χ. The worst case when there is this unerased area is when the previous recording position was recorded with a deviation of −β from the normal position, and the tracking shown in Figure 3 (c) was performed on it, and the head at this time The output is shown in FIG. 4 N3-3. At this time, it is expected that most of the errors will occur.

Therefore, when performing after-recording on only the channels in such a system with a multi-track, multi-channel configuration, in order to prevent the noise level from deteriorating during playback due to fluctuations in track linearity,
It is necessary to perform processing such as guard band recording or setting the track pitch during recording to be sufficiently large compared to the trace pitch during playback, resulting in a wider track pitch and a reduction in recording time. turn into.

[Purpose of the invention]

In view of the above points, the present invention provides a system that has a mode in which recording is performed discontinuously in the tape running direction.
The objective is to propose a recording method that can realize high recording density.

[Means for solving problems]

The present invention has been made to achieve the above objects,
The present invention will be explained with reference to FIG. 1. In a PCM recording device using a helical scan method, a reproducing circuit P feeds back recorded information in which a total of N channels exist to the recording encoder part 10 as new recorded information.
and a recording circuit R having a selector 9 for selecting input data based on external input data and this feedback data.

[For production]

When performing after-recording of M channels (M≦N) among N channels, adjacent channels in the tape running direction of the M channels are also re-recorded simultaneously through the feedback lines p, , pz. .

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 and 2. In this case, the number of channels is two, and each information data is recorded and encoded independently.

Figure 2 (0) shows the track format at this time, where 20 is the data track for channel 1 recorded at +azimuth, and 21 is the data track for channel 2 recorded at -azimuth. . FIG. 1 is a block diagram of a system capable of independently encoding and decoding the data of these two channels. On the recording side R, 7... are input terminals for channels 1 and 2, 8... is an A/D converter, 9...
are the digital data input from the A/D converter 8 and the feedback lines p, , P! from the playback side P! A selector 10 performs switching between reproduction output data fed back through the encoder, and a recording encoder 10 performs processing such as interleaving. 11 is an adder for data of these two channels, 12 is a recording amplifier, and 13 is a recording data output terminal. Furthermore, 1 on the playback side P
4 is the head output input terminal, 15 is the playback amplifier, 16 is the data distributor for channel 1 and channel 2, 17...
... is a reproduction decoder, and processes such as error correction, dinterleaving, and correction are performed here. The outputs of the reproduction decoders 17, 17 are input to the D/A converter 18 through delay circuits 23, 23. Reference numerals 19 and 19 are playback output terminals of the D/A converters 18 and 18.

Next, the operation of this device will be explained.

First, when newly recording channels 1 and 2, the selector 9 selects the input from the A/D converter 8, and the recording encoders 10 and 10 perform encoding and interleaving, respectively, and record. . After this, suppose you want to rewrite only channel 1. At this time, selector 9 on the channel 1 side is set to A as before.
/D converter 8 and selects the data from channel 2.
The selector 9 on the side is controlled to select the playback output side. On the playback side, the previously recorded data is simultaneously read out by the playback head, and channel 1. Both channel 2 undergoes processing such as error correction, dinterleave, and correction in the decoder, and outputs to the D/A converter 18.
This data is supplied to each selector 9. Therefore, new external information for channel 1 is recorded on the +azimuth track 20 as recorded information, and the same data as the previous channel 2, which has been read and corrected on the playback side, is newly recorded on the -azimuth track 21. become.

Therefore, when performing such partial after-recording, the adjacent trunk of that channel will also be newly recorded, so data of the same azimuth will not be left unerased as described above (however, if the track linearity is different from the adjacent track) Therefore, as a recording method, an overwriting (Tw>Tp) method is possible, and as a result, high recording density, which is the greatest advantage of the rotating head method, can be realized. Although the above embodiment has been described with a two channel configuration, it may have any number of channels.
Similarly, by feeding back the adjacent channels of the recording channel in the tape running direction and rerecording,
You can achieve the same effect. In addition, although the above has described problems related to the relationship with adjacent tracks, similar operations can be performed in a system where areas are divided in the track direction to create multiple channels. By re-recording all channels, it is also possible to remove the after-recording margin between channels.

〔effect〕

As explained above, in the present invention, by using a circuit that feeds back playback data and a circuit that can select it as input data, partial after-recording is performed.The existing recorded data is re-recorded through the feedback circuit. Therefore, adjacent pieces of unerased recorded data will always be recorded with different azimuths, and the level of noise caused by strokes will be reduced, so the override method (overwriting) can be adopted as the recording method, so high recording density can be achieved. It is.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG.
Figures (a), (b), and (c) show three models of linearity variation in the override method. FIG. 4 is a graph showing head output and noise level corresponding to FIG. 3. 10... Part of the recording encoder, P...
Reproduction circuit, 9...Selector, R...
Recording circuit, P+, Pz...feedback line. C? Tsuhei 30 Calculation g mouth q 5 Procedural litigation manual (method) % formula % 2. Name of the invention PCM recording and reproducing device 3. Person making the amendment Relationship to the case Patent applicant 002 Akai Electric Co., Ltd. 4. Agent Address: 2-1-8-5 Sanno, Ota-ku, Tokyo 143 Kumo
Date of amendment order: September 24, 1985 (shipment date)
6. Target of correction Drawing 7. Contents of correction

Claims (1)

[Claims] In a PCM recording device using a helical scan method, there is a reproducing circuit that feeds back recorded information for which N channels exist in total to a recording encoder section as new recorded information, and selects input data based on external input data and this feedback data. and a recording circuit having a selector, and when performing after-recording of M channels (M≦N) among N channels, adjacent channels in the tape running direction of the M channels are also recorded simultaneously through a feedback line. A PCM recording and reproducing device that is characterized by its ability to