JPS597127B2 - playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for reproducing signals recorded on magnetic tapes, magnetic disks, talkie films, etc., and has unprecedented features particularly in the reproduction of high-density recording. .

Conventionally, in magnetic tapes, magnetic disks, magnetic cards, etc., if the angle (azimuth) between the recorded signal and the playback head deviates, a phase shift occurs in the signal detected by the playback head, and the detected signal The problem is that the output is reduced, and the waveform is distorted and the rise characteristics of digital recording are deteriorated.

Normally, the decrease in output due to this phenomenon is called azimuth loss.
The shorter the recording wavelength and the wider the track width, the more rapidly this azimuth loss increases. Therefore, in order to reproduce signals with high recording density and a good S/N ratio, it is necessary to suppress the angular error to less than 1/10 degrees, making it difficult to adjust the angle of the reproducing head. There was also the problem that the output fluctuated greatly due to the extremely slight meandering movement of the card, which was a bottleneck in achieving higher recording density. The present invention has been made to solve the above-mentioned problems, and examples will be specifically described below. Figure 1a
and b show an embodiment in which the present invention is applied to a tape recorder. 1 and 2 are magnetic heads; 3 is a magnetic tape that runs in the direction of the arrow; signals are recorded with a track width of 4; the signals are reproduced by the magnetic heads 1 and 2, which are arranged approximately at right angles to each other.

In figure b, 1 and 2 indicate the magnetic heads in figure a, and 5 is a phase matching circuit that aligns the mutual phases of the signals reproduced by the magnetic heads 1 and 2. The signals aligned in phase by this circuit 5 are The signals are added together as shown in the figure and proceed to the next amplifier circuit, etc. Further, an amplifier circuit or the like may be inserted between the magnetic heads 1 and 2 and the circuit 5. The phase matching circuit 5 can be manufactured using a well-known technique using a delay element (BBD, surface acoustic wave element, magnetostrictive delay line, etc.). Next, the action and effects will be explained.

FIG. 2 shows experimental data showing the relationship between the angular error θ and the azimuth loss for recording by the reproducing head, and the track width W of the reproducing head and the recording wavelength λ are expressed as parameters.
As is clear from the figure, when a playback head with a track width of 1.5 mm is used, the azimuth loss is extremely large even with a slight angular error, and it increases further as the recording wavelength λ becomes shorter, but when the track width is O, 6n. Transient rear azimuth losses are reduced. Note that this experimental data agrees very well with the result of the theoretical equation obtained by integrating the output components whose phase is shifted due to the angular error. When the recording wavelength λ is 4.8μ and the angular error θ is 0.150, compared to reproduction using a reproduction head with a track width of 1.5n, for example, according to the present invention, the
, 6n width heads, and by aligning the phases of the respective reproduced signals and adding them together, the azimuth loss can be reduced by approximately 12 dB. Moreover, it will be even better if there are three or more heads. Even if a head is used for both recording and reproduction, even a slight meandering of the magnetic tape will cause azimuth loss and the output will fluctuate. This problem can be greatly improved by the device of the present invention. Precise angle adjustment required when using a head is also easier.
It is resistant to distortions caused by vibrations of the tape recorder, etc., so it is possible to rationalize the equipment. In particular, the shorter the recording wavelength is, the more remarkable the azimuth loss reduction effect of the present invention is. An improvement in recording density can be expected. Although the embodiment shown in Fig. 1 is explained using an ordinary electromagnetic induction type magnetic head, it is clear that the same effect can be obtained with a Hall element sensor, a detector using the Kerr effect, the Farade effect, etc. It can be used in a wide range of applications, such as tape recorders, video tape recorders, magnetic card devices, and magnetic disk devices.

Furthermore, the information is not limited to magnetic recording, but may also be a combination of something that utilizes the density of light (talkie film, optical disk, etc.) and a photodetector element. As described above, the reproducing apparatus of the present invention adds signals detected by a plurality of recording detecting elements arranged approximately perpendicularly to the traveling direction of the recording medium, aligning the mutual phases, and therefore recording and detecting. Decrease in playback output due to angular difference with the device (azimuth loss) and fluctuations in output due to meandering of the medium are significantly smaller than conventional products.
In particular, the shorter the recording wavelength, the greater the effect.
It has the feature that a device with high recording density can be easily obtained.

[Brief explanation of the drawing]

FIGS. 1A and 1B are schematic configuration diagrams showing one embodiment of a reproducing apparatus according to the present invention, and FIG. 2 is a characteristic showing the relationship between angular error and azimuth loss for recording of the reproducing head to explain the apparatus. It is a diagram. 1... Magnetic head (recording detection element), 3...
. . . Magnetic tape (magnetic recording medium), 5 . . . Phase matching circuit.

Claims (1)

[Claims] 1. It includes a plurality of recording detection elements arranged approximately perpendicular to the traveling direction of the recording medium, and a phase matching circuit that adds together the signals detected by the plurality of recording detection elements with their mutual phases aligned. Characteristic playback device.