JPH0715729B2 - Data playback device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data reproducing apparatus, and more particularly to a tape-shaped recording medium in which a plurality of tracks on which a predetermined amount of data is recorded are arranged in parallel in a predetermined direction. The present invention relates to a device for carrying and reproducing data.

[Conventional technology]

Conventionally, as data recorders for recording digital data, there have conventionally been proposed a data recorder using a disk-shaped recording medium such as a Protpy disk and a tape recorder.

By the way, in this type of data recorder, loss of recorded data is a fatal defect.
Therefore, when recording data, it is essential to confirm the recorded data in order to guarantee the reliability of the recorded data, so-called verify. This verification is performed in a conventional data recorder by a method suitable for the recording system, recording medium and other conditions.

FIG. 6 is a diagram showing a recording locus on a recording medium by a general data recorder using a disc-shaped recording medium, and FIG. 7 is a diagram for explaining the data arrangement on the recording locus of FIG. Reference numeral 1 denotes a disk-shaped recording medium, and 2a, 2b, 2c and 2d denote recording tracks on which one sector is recorded. In this type of data recorder, a plurality of sectors are recorded as shown in FIG. 7 (b) in response to the index pulse as shown in FIG. 7 (a). GAP in Fig. 7 (a)
The portion indicated by means a portion where no data is recorded. Data is arranged in one sector as shown in FIG. 7 (c). DATA in the figure is the main data to be recorded, DATASy
nc is main data synchronization data, ID is sub-data such as control data, IDSync is sub-data synchronization data, and CRCC is a known cyclic code (hereinafter referred to as CRCC).

In this type of data recorder, VeriFai reproduces immediately after recording and monitors the occurrence of data errors using the reproduced CRCC. The same data was recorded again in the same phase part of the above.

On the other hand, in the data recorder using the tape-shaped recording medium, as shown in FIG.
(Shown in FIG. 4), a recording head 5 located upstream and a veri-head head 6 located downstream are provided, and the error occurrence status of the data recorded by the recording head 5 is checked by the head 6 for verification.
Monitor with CRCC or Parity check code reproduced in. When a large number of data errors occur, the tape 3 is stopped from being conveyed and data recording is interrupted.

In addition, when data that cannot be error-corrected occurs during data reproduction, the tape 3 is rewound and repeatedly reproduced until error correction is possible for the same track.
It has been considered to increase the reliability of the reproduced data.

[Problems to be solved by the invention]

However, the amount of data that can be recorded is limited in the data recorder using the above-mentioned disk-shaped recording medium, and it is not suitable for storing a huge amount of data. On the other hand, a relatively large amount of data is recorded in a data recorder using a tape-shaped recording medium, but recording is stopped due to the occurrence of a data error during recording, so the average transmission bit rate of data must be reduced. And the recording time becomes very long. Further, even during reproduction, the tape is rewound and the data of the same track is reproduced every time error-correctable data is generated, so that it takes a very long time to reproduce. The long time required for recording and reproducing as described above remarkably reduces the utility value of the data recorder, and has hindered its widespread use for the data recorder using the tape recording medium.

[Means for solving problems]

For this purpose, the data reproducing apparatus according to the present invention is an apparatus for reproducing data by transporting a tape-shaped recording medium provided with a number of tracks in which a predetermined amount of data is recorded in parallel in a predetermined direction. With respect to all of the one or more tracks in which the data related to the same information is recorded, the transport direction of the tape-shaped recording medium is reversed in accordance with the fact that the reproduced data cannot be error-corrected. There is.

[Work]

By configuring as described above, when reproducing a portion in which data relating to the same information is continuously recorded in a plurality of tracks, the probability that the reproduction is temporarily stopped and the same track is reproduced again is reduced, The time required to reproduce the data can be shortened.

〔Example〕

 Examples of the present invention will be described below.

FIG. 2 is a diagram showing a schematic configuration of a data recording / reproducing apparatus according to an embodiment of the present invention. In the figure, 11 is a terminal to which an analog video signal obtained from a camera or the like (not shown) is input. In this data recorder, this analog video signal is converted into digital data and recorded and reproduced. 12 is an analog-to-digital (A / D) converter for digitalizing the analog video signal input to the terminal 11, 13 is a field memory capable of storing one field of the digitalized video signal, and 14 is a field memory 13 An address control circuit for controlling the write and read addresses of the data, 15 is data other than video data such as control data and character data (hereinafter referred to as ID
Is referred to as a PCM processor for outputting and outputting as PCM data after performing interleave processing on video data and ID, adding redundant codes such as error detection code and error correction code, etc. , 17 is PCM
The modulator 18 digitally modulates the PCM data output from the processor 16, and 18 is a recording amplifier.

SW1, SW2, and SW3 are switching switches, 21 is a reproduction amplifier, 22 is a demodulator corresponding to the modulator 17, and 23 is a demodulator.
An error detection circuit that detects the number and pattern of occurrences of data errors using the error detection code and error correction code in the PCM data obtained through 22, 24 is a system control circuit that controls the entire device, and 25 is a PCM processor. A PCM processor that performs processing reverse to that of 16, i.e., deinterleave processing and error correction processing, 26 is an ID processing circuit that outputs data other than various control data and video data based on the ID obtained from the PCM processor 25, and 27 is A field memory for receiving the video data output from the PCM processor 25, an address control circuit 28 for controlling the write and read addresses of the field memory 27, and an analog output 29 for the digital video data read from the field memory 27. A digital-analog (D / A) converter, 30 is an output terminal for an analog video signal.

H1 and H2 are rotating heads, respectively, and the arrangement thereof will be described with reference to FIGS. 3 (A) and 3 (B). Figure 3 (A)
As shown in, the head H1 and the head H2 are mounted on the rotating cylinder 50 with a phase difference of 180 ° with respect to each other, and the magnetic tape T makes an angle of less than 180 ° (θ
It is wound over the angle range of (°). The head H1 is used for data recording / reproduction and the head H2 is used for data reproduction. As shown in FIG. 3 (B), the head H1 and the head H2 have the same azimuth and a predetermined distance x in the direction of the rotation axis. Only rotate on different rotation planes. This distance x is the head H1
If recording is performed only by using the track and the length of the track is sufficiently smaller than the recording track pitch, the recording track pitch is halved. As a result, heads H1 and H2 are shown in Fig. 4.
Take the center line of the trace locus as shown by t1 and t2, and
The trace trace of 1 will be traced as head H2 follows.

Hereinafter, the data recording and reproducing operation in the data recorder having the above configuration will be described.

FIG. 5 is a flow chart showing the operation of the system control circuit 24 at the time of data recording. The operation at the time of data recording will be described below with reference to the flow chart of FIG. When recording data, the switches SW1 and SW3 are connected to the R side.

One field of digital video data output from the A / D converter 12 is written in the field memory 13 according to the operation of an operation member (not shown). Since the bit rate of digital data obtained by digitalizing a video signal in real time is extremely high, the field memory 13 outputs video data of one field, that is, still image data at a reduced bit rate. Along with this, the video data for one field is recorded over many tracks.

In step 101 of FIG. 5, an ID is set by the ID processing circuit 15. The track number data indicating the track number of the data recorded in one field of the ID data, etc. It is included. When the recording head H1 reaches the specified rotation phase, the head H1
Data for one track is recorded through the R side terminal 3 (step 102). This recording ends when the drum 50 rotates by θ °, and when the drum 50 further rotates by (180−θ) °, the playback head H2 reaches the beginning of the track just recorded, and this track is transferred to the playback head H2. And replay (step 103).

The reproduction signal of the reproduction head H2 is input to the demodulator 22 via the R-side terminal of SW1 and the recording amplifier 21, and the error detection circuit
The number 23 of the data error, the generation pattern, and the like are detected by using the error correction code and the like output from the demodulator 22. At this time, if it is determined in step 104 that no data error has occurred, a part of the ID of the track number data or the like is updated (step 105), and the data to be recorded next is loaded from the field memory 13 to the PCM processor 16. Yes (Step 10
6). If the data to be recorded is completed here, the process based on this flow chart is completed, and if not completed, the process returns to step 102 (step 107) to record new data to the next track. To do.

On the other hand, when it is determined that a data error has occurred in step 104, the number of data error occurrences is checked in step 108, and the data error occurrence pattern is checked in step 109. If it is determined that the error correction is possible in step 110 based on these checks, the process returns to step 102 via steps 105 and 106, and new data is recorded in the next track in the same manner. If it is determined in step 110 that the error cannot be corrected, the process returns to step 102 without updating the ID and the data, and the same data is recorded again for the next track.

In the processing according to the flow chart of FIG. 5, the processing time from the end of the reproduction of step 103 to the start of the reproduction of step 102 is set to be within the period in which the cylinder 50 rotates by θ °. Needless to say.

As described above, when it is determined by the verifiy immediately after recording that the recording data cannot be error-corrected, the same data is repeatedly recorded, and the rotation of the drum 50 and the running of the tape T are stopped. Data can be recorded without any trouble. Therefore, data recording is performed one after another, and highly reliable data can be recorded in a short time.

FIG. 1 is a system control circuit at the time of reproduction by the apparatus of FIG.
24 is a flowchart for explaining the operation of 24, and the operation at the time of reproduction will be described below.

During reproduction, the switches SW1 and SW3 are connected to the P side, respectively, and the switch SW2 is alternately connected to both terminals A and B by a control circuit (not shown) every time the head drum 50 rotates 180 °.

The ID reproduced by the head H1 is read (step 20
After 1), when it is determined in step 202 that data is recorded, the output of the error detection circuit 23 determines whether or not a data error has occurred (step 203).
When there is no data error, the variable X is "1".
Is registered (step 220).

On the other hand, if a data error has occurred, the number of error occurrences is checked (step 205) and the error occurrence pattern is checked (step 206) based on the detection result of the error detection circuit 23. A determination is made as to whether the correction is possible. If the error can be corrected, the error correction processing is performed in step 208, and then the process proceeds to step 220, and "1" is set in the data X. If it is determined that the error cannot be corrected, the switch SW2 is waited for connection to the B side, the ID output from the head H2 is read (step 209), and the same operation as steps 203 to 208 is performed. H
The reproduction data from step 2 is performed (steps 213-121).
8).

After that, when the switch SW2 is connected to the A side again, the ID reproduced by the head H1 is read (step 209),
The track number data in the ID read this time is compared with the track number data in the ID read last time. Accordingly, it is determined whether the track to be reproduced this time and the track reproduced immediately before are data related to the same information, that is, whether the data has been updated (step 221). If the data has not been updated,
It can be determined that the track is the second track or later of the portion where the same data was recorded over a plurality of tracks due to the verifying at the time of recording, and in this case, the process returns to step 202.

If the data has been updated, it is determined whether the information recorded in the track reproduced immediately before can be output. In the signal reproduced from the immediately preceding reproduction track or the previously reproduced track, if at least one of the data relating to the same information as the immediately preceding reproduction track has error correctable data reproduced, it is set to X. Since "1" should have been registered, it is sufficient to judge in step 222 whether "X = 1". "X =
If it is "1", the corrected data or the error-free data is output from the PCM processor 25 (step 22).
3). When the output of data is completed, "0" is set in the variable X and a variable N described later.

If "X = 1", that is, if X = 0, it means that the error-correctable data cannot be reproduced from any of the tracks or any of the heads of the information to be reproduced. In this case, the tape is rewound by a predetermined amount at step 227 and the same track is reproduced again. The variable N is a variable for counting the number of rewinds,
Each time the tape is rewound, step 226 adds 1 to N. If the error-correctable data cannot be reproduced even after the tape is rewound M times, step 225, “N”
= M ”, the process is terminated. See also step 202
Even if there is no more data to be played back, the processing ends.

According to the operation at the time of reproduction as described above, the opportunity to temporarily stop the tape and rewind the tape can be error-corrected from both the head H1 and the head H2 for any one or more tracks in which the same information is recorded. Since it is only when the data cannot be reproduced, the time required for reproduction is greatly shorted. Further, since the head used for performing the verify operation during recording and the head used for recording are both used for reproduction, the number of heads can be minimized.

〔The invention's effect〕

As described above, according to the data reproducing apparatus of the present invention,
The time required to reproduce the data can be significantly reduced, and the applications of the data recorder using the tape-shaped recording medium can be expanded.

[Brief description of drawings]

FIG. 1 is a flow chart for explaining the operation at the time of reproduction of a data recorder as one embodiment of the present invention, and FIG. 2 is a diagram showing a schematic configuration of a data recorder as one embodiment of the present invention. (A) and (B) are diagrams showing the head layout of the recorder of FIG. 2, FIG. 4 is a diagram showing a trace locus by each head of the recorder of FIG. 2, and FIG. 5 is a diagram of the recorder of FIG. A flow chart for explaining the operation of the system control circuit at the time of recording, FIG. 6 is a diagram showing a recording locus on the recording medium by a general data recorder using a disk-shaped recording medium, and FIG. 7 is FIG. FIG. 8 is a diagram for explaining the data arrangement on the recording locus of FIG. 8, and FIG. 8 is a diagram showing an example of a conventional data recorder using a tape-shaped recording medium. In the figure, H1 is the first rotary head, H2 is the second rotary head,
T is a tape, 16 and 25 are PCM processors, 23 is an error detection circuit, and 24 is a system control circuit.

Claims (2)

[Claims] 1. An apparatus for reproducing data by transporting a tape-shaped recording medium having a plurality of tracks on which a predetermined amount of data is recorded in parallel in a predetermined direction and reproducing the data. The data reproducing apparatus is characterized in that the conveying direction of the tape-shaped recording medium is reversed in accordance with the fact that the reproduced data of all of the one or more tracks in which is recorded cannot be error-corrected. 2. A plurality of heads for continuously tracing the same track while the tape-shaped recording medium is being conveyed in the predetermined direction, and data reproduced from any of the plurality of heads for all of the one or more tracks. The data reproducing apparatus according to claim (1), wherein the transport direction of the tape-shaped recording medium is reversed when the error correction cannot be performed.