JPH0472282B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a magnetic storage device that simultaneously stores and reproduces information on a plurality of tracks, and in particular, it is capable of reproducing information recorded at a track density lower than the magnetic head track density. Related to magnetic tape devices.

[Prior art]

Conventionally, in standard 1/2 inch magnetic tape devices, it has been common to record and reproduce information on nine tracks at the same time, but recently an 18-track system has been developed. When the number of tracks is increased in this way, the track density naturally increases,
The track density of the magnetic head must be increased accordingly. It goes without saying that it would be convenient if such a magnetic storage device having a magnetic head with a high track density could be used to read information recorded with a conventional low track density.

However, it has been virtually impossible to reproduce information from a recording medium recorded at a track density different from the magnetic head track density. In other words, in order to make it playable, it is necessary to convert the head and circuit, and the track density of the medium is lower, and the track density of the magnetic head is higher by an integral number of times, and it is difficult to correspond to each track of the recording medium. When information is reproduced using each track of a magnetic head, the effective track width parasitic to information reproduction becomes narrower, resulting in a decrease in S/N and an increase in errors due to dropouts (signal dropout phenomenon). It was hot.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magnetic storage device that can reliably reproduce information recorded at a track density lower than that of a magnetic head, in order to overcome these conventional drawbacks.

[Summary of the invention]

To achieve the above object, the present invention provides information that is read out by the magnetic head when reproducing information stored on the magnetic storage medium using a magnetic head that has a track density that is an integral multiple of the track density of the magnetic storage medium. The information is divided into a plurality of information groups including information on each track of the magnetic storage medium, an error correction/detection circuit is individually provided for each information group, and an error-free information group is selected from among the information groups. The feature is that it is selected as playback information.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

Figure 1 shows that when the present invention is applied to an 18-track magnetic storage device using 1/2-inch standard magnetic tape, this device can be used to store 9 tracks using 1/2-inch standard magnetic tape. FIG. 3 is a diagram showing the correspondence between track b on a medium and magnetic head track a when reproducing information.

As shown in Fig. 1, the track positions of the 18 tracks of the magnetic head are arranged with a track pitch of 700 μm and a track width of 400 μm, while information on 9 tracks on the recording medium is arranged with a track pitch of 1400 μm and a track width of 1100 μm. Because of the array, two tracks on the magnetic head track each correspond to one track on the medium. However, the track width on the recording medium is 1100 μm.
In contrast, the magnetic head track width is 400μ
m, and even if it is read with 2 tracks, the total track width of the 2 tracks is 800 μm, so
The effective magnetic head track width that contributes to information reproduction is narrower than the track width on the recording medium.
As a result, errors increase due to dropouts.

On the other hand, the conventional error correction detection method, as shown in Japanese Patent Publication No. 53-27103 or Japanese Patent Publication No. 56-26063, performs logical operations on information on nine tracks to correct and detect errors on nine tracks at the same time. It's on.

Therefore, in this embodiment, as shown in FIG.
The error correction detection logic circuits 10 and 20 are provided in a magnetic storage device for 18 tracks, the 18 magnetic head tracks are divided into two groups of odd numbers and even numbers, and each of the two groups of magnetic head tracks is subjected to error correction detection. By making it correspond to the logic circuits 10 and 20, error correction detection is performed. At this time, the occurrence of an error that cannot be corrected after calculation is indicated on signal lines 30 and 40 (in the figure, a positive signal indicates the occurrence of an error). Now, error correction detection logic circuit 1 for odd numbered tracks of magnetic head tracks.
Assume that an error that cannot be corrected with 0 has occurred, and that the error correction detection logic circuit 20 has corrected all errors. In this case, a positive signal is output to the signal line 30 and a zero signal is output to the signal line 40. The positive signal sent to the signal line 30 is inverted by the inverter 45 and input as a zero signal to the AND circuit group 35, so the output of the AND circuit group 35 is always zero.
Information from odd numbered magnetic head tracks is not output. On the other hand, the zero signal sent to the signal line 40 is inverted by the inverter 45' and input as a positive signal to the AND circuit 55, and since the positive signal of the signal line 30 is input to the AND circuit 55,
The output of the circuit 55 becomes a positive signal, and the positive signal becomes
Since the information is input to the AND circuit group 35', the AND circuit group 35' outputs the information from the even-numbered magnetic head tracks, and in the end, the OR circuit 50 selects and outputs the information read by the even-numbered magnetic head tracks. do. On the contrary, if an error that cannot be corrected occurs in the error correction detection logic circuit 20 but not in the error correction detection logic circuit 10,
Conversely, information read by odd numbered magnetic head tracks is selected. If an error that cannot be corrected occurs in both logic circuits 10 and 20, positive signals from signal lines 30 and 40 are input to AND circuit 55' to obtain signal 60 indicating that an error has occurred.

In the above explanation, we have talked about the occurrence of errors that cannot be corrected, but correctable errors (correctable errors are not output to signal lines 30 and 40) also occur in the group with the smaller number of corrected tracks. It is clear that the reliability of the data will be further improved if this is adopted as the output. At this time, the number of odd-numbered magnetic head tracks corrected by the error correction detection logic circuit 10 is T _E1 ,
Assuming that the number of even-numbered magnetic head tracks corrected by the error correction detection logic circuit 20 is T _E2 , T _E1 is 70 and T _E2 is 80, as shown in FIG.
(assumed to be represented by a binary code) into a comparator 90 to compare the number of errors corrected. The comparator 90 can be easily realized with an off-the-shelf element (for example, Hitachi HD7485). The output of comparator 90 is signal 1 indicating T _E1 > T _E2 .
00, a signal 110 indicating T _E1 = _TE2 , and a signal 120 indicating T _E1 < _TE2 . Using each of these signals, AND gate group 3 is connected as shown in Figure 3.
By switching to select 5 or AND gate group 35', information from a reproduced data group with a small number of modified tracks can be easily obtained. Note that the signal 110 indicating T _E1 = T _E2 and T _E1
Since the signals 120 indicating <T _E2 are both input to the OR circuit 130, it goes without saying that in both cases, information from odd-numbered magnetic head tracks is selected.

Most of the errors that occur in magnetic tape devices are dropouts (reduction in signal amplitude due to the intrusion of dust or the like between the head and the recording medium). As shown in Figure 4, the frequency of dropout occurrence is 4a, which occurs in one track alone.
The frequency 4b in which two tracks simultaneously occur is one to two orders of magnitude lower than that, and as the number of tracks in which dropouts occur simultaneously increases, the frequency of dropouts decreases. Therefore, if this embodiment is applied, it is only necessary that one of the reproduced data groups for each error correction/detection is correct, so the occurrence of errors due to dropouts can be suppressed by one to two orders of magnitude, and the reliability of the device is improved. can be improved.

The horizontal axis in FIG. 4 shows the residual signal level at the time of dropout as a ratio to the signal level at the point where no dropout occurs, and the vertical axis shows the number of dropouts per magnetic tape roll.

〔Effect of the invention〕

As described above, according to the present invention, information on a recording medium having a track density lower than the magnetic head track density is read out using magnetic head tracks divided into a plurality of groups, and the information from each group is individually error-detected and processed. Make the correction,
By selecting the information in the group with the smaller number of errors, it is possible to reliably reproduce information recorded at a track density lower than that of the magnetic head.

[Brief explanation of the drawing]

FIG. 1 shows an example of the track correspondence relationship when the number of magnetic head tracks and the number of tracks on the recording medium differ by an integral multiple, and FIG. 2 shows an example of the present invention when an error that cannot be corrected occurs. 3 and 3 are diagrams showing an embodiment of the present invention when corrected track numbers are compared, and FIG. 4 is a diagram showing the frequency of dropouts. 10, 20... Error correction detection logic circuit for 9 tracks, 30, 40... Signal line indicating occurrence of error, 35, 35'... AND circuit group, 50...
OR circuit group, 55, 55'...AND circuit, 60...
...Signal line indicating error occurrence in 9 tracks after playback.

Claims (1)

[Claims] 1. In a magnetic storage device that simultaneously reproduces information on multiple tracks, when reproducing information stored on the magnetic storage medium using a magnetic head having a track density that is an integral multiple of the track density of the magnetic storage medium, the magnetic head The information read by the above is divided into a plurality of information groups each including information on each track of the magnetic storage medium, and an error correction/detection circuit is provided for each information group. What is claimed is: 1. A magnetic storage device characterized in that an information group without a .