JPH0554559A - Magnetic tape reproducing device - Google Patents

Abstract

PURPOSE:To increase the error correction capability of a digital signal read out from a magnetic tape. CONSTITUTION:A first reproducing head 1 to the upstream side of the magnetic tape 3 and a second reproducing head 2 to the downstream side are arranged. The digital signals are obtained from the output of the first and the second reproducing heads 1, 2 by a first and a second signal processing circuits 4, 5. The regenerative signal data from the first signal processing circuit 4 is delayed by a delay circuit 7 and applied to a data inserting circuit 9. When an error is detected by an error detecting circuit 6, a switching circuit 8 is switched and the regenerative signal data from the second signal processing circuit 5 is inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reproducing a magnetic tape in which acoustic signals and the like are recorded by digital signals.

[0002]

2. Description of the Related Art A conventional magnetic tape reproducing apparatus, for example, a fixed head type digital tape recorder reproduces a digital signal recorded on a magnetic tape by using one reproducing head. By converting an acoustic signal or the like from an analog signal to a digital signal, recording it on a magnetic tape, reading it as a digital signal, converting it to an analog signal and reproducing it, so-called hiss noise or the like can be eliminated.

However, when the recorded digital signal cannot be read correctly, the level of the analog signal for converting the read digital signal changes abruptly, large noise is generated, and a speaker for audibly reproducing the reproduced signal is used. It may be damaged. Therefore, information for error detection and error correction is added in advance to the digital signal recorded on the magnetic tape, and it is possible to determine whether or not the digital signal read from the magnetic tape contains an error. When it is included, it can be corrected to some extent. For example, parity, cyclic code (abbreviated as “CRCC”), Reed-Solomon code, etc. can be used to detect errors due to various causes and modes, and some of them can be corrected to correct signals. ..

[0004]

In a conventional reproducing apparatus for reading a digital signal from a magnetic tape with one reproducing head, it is not possible to sufficiently correct the code error of the read digital signal. In order to correct the code error, it is necessary to add a lot of correction information when recording the digital signal on the magnetic tape, and further it is necessary to perform complicated arithmetic processing after reading from the magnetic tape. is there.

The cause of the error in the digital signal read from the magnetic tape is that dust or magnetic powder adheres to the reproducing head or the magnetic tape is scratched. Due to these causes, if a code error occurs in the digital signal read from the magnetic tape, the error can be detected but cannot be corrected sufficiently, and the audio signal can be reproduced with good sound quality. I can't.

An object of the present invention is to provide a magnetic tape reproducing device having an improved error correction capability.

[0007]

According to the present invention, there is provided a first reproducing head for reading out a digital signal recorded on a magnetic tape, and a first reproducing head arranged in the running direction of the magnetic tape with a space therebetween. A second reproducing head for reading the digital signal and an error detecting means for detecting a code error of the read digital signal in response to the output from the first reproducing head, and a digital signal for responding to the output from the error detecting means. Switching means for switching to reproduce the digital signal read by the first reproducing head when no code error of the signal is detected, and reproducing the digital signal read by the second reproducing head when the code error is detected. This is a magnetic tape reproducing apparatus characterized by the above.

Further, the present invention is characterized in that at least one of the first reproducing head and the second reproducing head is a recording / reproducing head.

[0009]

According to the present invention, the digital signal recorded on the magnetic tape is read by the first reproducing head and the second reproducing head. The second reproducing head is arranged at a distance from the first reproducing head in the running direction of the magnetic tape.
The error detecting means detects a code error in the digital signal read by the first reproducing head. When no code error is detected,
The switching means reproduces the digital signal from the first reproducing head and reproduces the signal from the second reproducing head when a code error is detected. The state of adhesion of dust or the like to the reproducing head and the positional relationship between the scratches on the magnetic tape and the reproducing head are not necessarily the same as those of the first and second reproducing heads. Therefore, at least one of the first and second reproducing heads may be able to correctly read the digital signal even if a code error is detected in the other.
Therefore, even if an error is detected in the digital signal read by the first reproducing head, there is a possibility that the error is not detected in the digital signal read by the second reproducing head, and the switching means uses the digital signal from the second reproducing head. By switching so as to reproduce, it is possible to increase the possibility of reproducing a digital signal having no code error.

According to the invention, at least one of the first reproducing head and the second reproducing head is a recording / reproducing head. Generally, the track width read by the reproducing head is smaller than the track width when recording on a magnetic tape. This is so that the signal can be read from within the recorded track even if the relative positions of the magnetic tape and the reproducing head are deviated. Since the recording / reading head also performs recording / reading with a track width equivalent to that of the recording head, the read-out track width from the magnetic tape becomes larger than that of the read-only head. Therefore, even when the magnetic tape is damaged, the contribution of the damage to the code error is different, and the digital signal read by the recording / playback head having a larger read track width has a code error. Is less likely to occur.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the electrical construction of an embodiment of the present invention. The first reproducing head 1 and the second reproducing head 2 read the digital signal recorded on the magnetic tape 3. The second reproducing head 2 is arranged on the downstream side of the magnetic tape 3 with a space from the first reproducing head 1, and reads the same recording track as the recording track on the magnetic tape 3 read by the first reproducing head. Is arranged as. First reproducing head 1 and second
The output from the reproducing head 2 is given to the first signal processing circuit 4 and the second signal processing circuit 5, respectively. The first and second signal processing circuits 4 and 5 amplify the signals from the first and second reproducing heads 1 and 2 and discriminate the levels to obtain digital signals. The first and second signal processing circuits 4 and 5 separate the error correction information added to the digital signal from the sound reproduction signal data.

The error detection information from the first signal processing circuit 4 is given to the error detection circuit 6 which is an error detection means. The error detection circuit 6 detects the first error based on the error detection information.
It is determined whether or not there is an error in the digital signal read by the reproducing head 1. As error detection information, parity or C
Since RCC, Reed-Solomon code, etc. are included, it is easy to determine whether or not the reproduced signal data output from the signal processing circuit 4 contains an error. Signal processing circuit 4
The reproduction signal data from is supplied to the delay circuit 7 and is delayed by the time during which the magnetic tape 3 moves from the first reproduction head 1 to the position of the second reproduction head 2. The reproduction signal data from the second signal processing circuit 5 is given to the switch circuit 8. When the error detection circuit 6 detects a code error in the digital signal output from the first signal processing circuit 4, the error detection circuit 6 derives an error signal. This error signal controls the switching state of the switch circuit 8. When the error signal is generated, the switch circuit 8 gives the reproduced signal data from the second signal processing circuit 5 to the data insertion circuit 9. The data insertion circuit 9 inserts the reproduction signal data from the second signal processing circuit 5 given through the switch circuit 8 into the reproduction signal data from the delay circuit 7.

FIG. 2 shows points (a), (b),
The error correction state in (c) and (d) is shown. For convenience of explanation, it is assumed that the reproduction signal data from the first signal processing circuit 4 includes error data as indicated by the hatched line (a). This reproduction signal data is delayed by the delay circuit 7 as shown in (b). Since the first data contains error data, the error detection circuit 6
The switch circuit 8 is turned on by the error signal from. At this time, FIG. 2C from the second signal processing circuit 5
2 is given to the data insertion circuit 9 and inserted into the first signal position of the reproduced signal data from the delay circuit 7 as shown in FIG. 2 (d). As a result, the reproduced signal data shown in (d) given from the data insertion circuit 9 to the reproducing circuit can be prevented from containing an error.

FIG. 3 shows the electrical construction of another embodiment of the present invention. This embodiment is similar to the embodiment shown in FIG. 1, and corresponding parts are designated by the same reference numerals. It should be noted that the recording / playback head 10 is provided in place of the second playback head 2 so that the recording / playback width is larger than the playback trace width of the first playback head 1.
That is, the reproduction trace width of the reproduction head 10 is larger.

FIG. 4 shows the relationship with the reproduction trace width when the scratched portion 11 shown by hatching appears on the magnetic tape 3. The track width during recording is set larger than the trace width during playback, and even if the playback trace position fluctuates due to variations in the tape running mechanism, instability of tape running, etc. It is supposed not to. In the recording / reproducing head 10, since recording and reproduction are performed by the same head gap, the trace width during reproduction also becomes equal to the track width during recording. Therefore, the influence of the scratched portion 11 is reduced, and the possibility that the digital signal to be read contains an error is reduced.

The structure provided with the recording / reproducing head 10 as shown in FIG. 3 can be suitably used especially for a digital recording / reproducing apparatus for music editing. Since a digital recording / reproducing apparatus for editing music requires a so-called punch-in / out function, a reproducing-only head and a recording-only head are usually provided. With respect to the running direction of the magnetic tape, the read-only head is arranged on the upstream side and the record-only head is arranged on the downstream side. By arranging the two heads in this way, it is possible to realize a punch-in / out function of playing back a recorded music performance or the like while recording another performance content on the defective portion or the like. By using the recording / reproducing head 10 shown in FIG. 3 instead of such a recording-only head, the error correction capability can be improved. The recording / reproducing / signal processing circuit 12 shown in FIG. 3 is the second signal processing circuit 5 shown in FIG.
The same signal processing as above and signal processing when the recording / reproducing head 10 is used for recording a digital signal are also performed. The switch circuit 13 is switched to the reproducing side when the recording / reproducing / signal processing circuit 12 performs the reproducing signal processing, and is switched to the recording side when performing the recording signal processing.

In the embodiment shown in FIG. 3, the first reproducing head 1 for reproduction is arranged on the upstream side in the traveling direction of the magnetic tape 3, and the recording / reproducing head 10 is arranged on the downstream side. It goes without saying that the recording / reproducing head may be arranged on the upstream side of the tape 3 and the reproduction-only head for monitoring during recording may be arranged on the downstream side. Even in the case of such an arrangement, the reproduction trace width of the head is different and the influence of the scratched portion of the tape can be reduced.

Further, in each embodiment, it is needless to say that the number of recording tracks provided on the magnetic tape 3 may be plural, and the code error of the digital signal for each track is detected to reproduce the reproduction signal data. Of course, the insertion can be done.

[0019]

As described above, according to the present invention, the first and second reproducing heads read the digital signal from the magnetic tape, and when no error is detected in the digital signal read by the first reproducing head, the first reproducing is performed. Since the digital signal from the head is reproduced and the digital signal read by the second reproducing head is reproduced when an error is detected, the error correction capability of the digital signal read from the magnetic tape can be improved. Moreover, since it is not necessary to add new error correction information to the digital signal recorded on the magnetic tape,
It is not necessary to perform a process different from the conventional process when recording the digital signal on the magnetic tape.

Further, according to the present invention, the first reproducing head and the second reproducing head have different track widths when reading a digital signal from the magnetic tape. Therefore, even if the magnetic tape is scratched or the like, one reproducing head may be able to correctly read the digital signal, and thus the error correction capability of the reproducing signal can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a data insertion state according to the embodiment shown in FIG.

FIG. 3 is a block diagram showing an electrical configuration of another embodiment of the present invention.

FIG. 4 is a diagram for explaining an effect in the embodiment shown in FIG.

[Explanation of symbols]

 1, 2 reproducing head 3 magnetic tape 4,5 signal processing circuit 6 error detection circuit 7 delay circuit 8 switch circuit 9 data insertion circuit 10 recording / reproducing head 11 scratched portion 12 recording / reproducing / signal processing circuit

Claims (2)

[Claims] 1. A first reproducing head for reading a digital signal recorded on a magnetic tape, and a second reproducing head for reading the digital signal, which is arranged at a distance from the first reproducing head in the running direction of the magnetic tape. Error detecting means for detecting the code error of the read digital signal in response to the outputs from the reproducing head and the first reproducing head, and when the code error of the digital signal is not detected in response to the output from the error detecting means. A magnetic tape reproducing means for reproducing the digital signal read by the first reproducing head, and switching to reproduce the digital signal read by the second reproducing head when a code error is detected. apparatus. 2. The magnetic tape reproducing apparatus according to claim 1, wherein at least one of the first reproducing head and the second reproducing head is a recording / reproducing head.