JPS6037521B2 - magnetic recording and reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording/reproducing device such as a tape recorder or a magnetic disk device, and is particularly intended to eliminate waveform distortion based on hysteresis of a magnetic medium.

A magnetic recording/reproducing device has a disadvantage in that the reproduced signal suffers waveform distortion due to the magnetic hysteresis of the magnetic medium. In other words, when recording on a magnetic medium using a magnetic head, the magnetic field generated by the magnetic head has a certain spread around the magnetic gap. For this reason, it is thought that magnetic addition and subtraction is performed at the joint between signals. Therefore, if the magnetic medium has hysteresis as shown in FIG. 1, the reproduced waveform will be subjected to waveform distortion as shown in FIG. 2a. Note that FIG. 2b shows a normal sine waveform. In particular, the time required for the first half cycle of the waveform T. Since it passes through the initial curve D of the hysteresis characteristic shown in FIG. 1, it becomes longer than the time interval 2 required for each subsequent half cycle.
For this reason, when playing music, expressions such as the beginning of a song having a bad rise or attack are used. It is an object of the present invention to provide a magnetic recording/reproduction disk which eliminates reproduction distortion due to hysteresis of a magnetic medium and allows the time required for a half cycle of rise to be a normal length. The present invention provides a magnetic recording/reproducing device including a simulating circuit that simulates waveform distortion based on magnetic hysteresis of a magnetic medium in either the recording or reproducing system, and a distortion output from the simulating circuit. A subtraction circuit is inserted to calculate the difference between the signal and the original signal supplied to the Harini circuit.

An embodiment of the present invention will be described in detail below with reference to FIG. In FIG. 3, 1 indicates, for example, a reproduced signal source.

The reproduction signal source 1 may be a single reproduction head, or may include a reproduction amplifier. The output signal of the reproduced signal source 1 is supplied via a buffer amplifier 2 as necessary to an approximate circuit 3 which gives a simulated distortion equivalent to the waveform distortion based on the hysteresis of the magnetic medium. This simulated circuit 3 includes a magnetic field generating means 4 connected to the output side of the buffer amplifier 2, a magnetoelectric conversion element 5 that detects the magnetic field of the magnetic field generating means 4,
It is constituted by an amplifier 6 that amplifies the electrical output of this magnetoelectric conversion element 5. For example, a Hall element or other magnetically sensitive element can be used as the magnetoelectric conversion element 5. The example shown in the figure shows a case where a Hall element is used, and 9 indicates a DC power supply for flowing a constant current between the current terminals of the Hall element. The magnetic field generating means 4 is constituted by a core and a coil attached to the core, and supplies the output current of the buffer amplifier 2 to the coil.
An annular core is used as the core, a magnetic gap is provided in a part of the annular core, a magnetic force conversion element 5 is inserted into this magnetic gap, and the magnetic field generating means 4 and the magnetoelectric conversion element 5 are tightly coupled. In this case, if the material of the core is selected so that the magnetic hysteresis characteristic of the core constituting the magnetic field generating means 4 is almost equal to that of the magnetic recording medium, the signal will not become magnetic in the process of passing between the magnetic field generating means and the magnetoelectric transducer 5. It receives distortion that is almost equivalent to the distortion that occurs in the recording medium. Therefore, assuming that the original signal is subject to distortion due to the hysteresis of the magnetic medium,
The output of the simulated circuit 3 is subjected to distortion approximately twice that amount. The output of the simulating circuit 3 is supplied to one input terminal of the subtraction circuit 7. The other input terminal of the subtraction circuit 7 is connected to the reproduction signal source 1.
directly supplies the output of The subtraction output of the subtraction circuit 7 is supplied to an addition circuit 8, where it is added to the reproduced signal. With this configuration, it is possible to obtain a reproduced signal from which distortion has been removed at the output of the adder circuit 8. The explanation will be given below. The magnetic core of the magnetic field generating means 4 also has hysteresis as described above. Therefore, the output signal of the magnetoelectric transducer 5 is subjected to distortion due to the magnetic hysteresis of the magnetic core constituting the magnetic field generating means 4. As a result, the signal output from the amplifier 6 has a waveform that rises later than the rise of the signal a output from the reproduced signal source 1 as shown in FIG. Figure 4 shows the details. In Figure 4 a
indicates the reproduced signal of the reproduced signal source 1, and c indicates the output signal of the amplifier 6. A circuit 7 that subtracts the output signal of the amplifier 6 from the reproduced signal a.
By subtracting , a correction signal d having a second harmonic component as shown in FIG. 4 is obtained. This correction signal d is the difference between a distorted wave based on the hysteresis of the magnetic medium and a distorted wave twice that amount, and can be approximated to the difference between the sine wave and the reproduced signal a. Therefore, by adding this correction signal d to the reproduced signal a in the adding circuit 8, the rise is normal, that is, the time required for a half cycle of the rise is equal to the time required for the subsequent half cycle, and distortion is removed. Fourth
A sine wave b as shown in the figure can be obtained. As explained above, according to the present invention, it is possible to remove the distortion of the reproduced signal caused by the hysteresis of the magnetic medium in a magnetic recording/reproducing device, and the head half cycle of the reproduced wave is changed from each subsequent half cycle. It is also possible to correct the fact that the time is longer than the time required for the attack, and it is possible to reproduce a signal with a normal attack.

FIG. 5 shows another embodiment of the invention.

In this example, a differential amplifier is used as the amplifier 2 that excites the magnetic field generating means 4, and this differential amplifier 2 is configured to also serve as the subtraction circuit 7. Therefore, in this case, the difference signal d is output to the output side of the differential amplifier 2,
By adding this difference signal to the reproduced signal in the adding circuit 8, it is possible to correct the distorted reproduced signal to a sine wave as in the case of FIG. In the above description, a case has been described in which the analog circuit 3 for obtaining a correction signal having a distortion of the opposite polarity to the distortion caused by the hysteresis of the magnetic medium is inserted into the reproduction signal system, but it is not necessarily necessary to do so; for example, it may be inserted into the recording system. By recording in advance with reverse polarity distortion, a reproduced signal can be obtained with a normal waveform.

In addition, in the above, the subtraction result is combined with the adder 8, but the level of the original signal fed into the subtracter 7 is set to double, and the difference signal is subtracted from the original signal having twice the level. You can also.

In this case, the adder circuit 8 is not necessary, so the adder circuit 8
It is easy to understand that these are excluded from the constituent elements of this invention. As explained above, according to the present invention, it is possible to remove the distortion of the reproduced signal caused by the hysteresis of the magnetic medium of the magnetic recording and reproducing device, and it is also possible to obtain a reproduced signal with a normal attack. It's large.

[Brief explanation of the drawing]

Fig. 1 is a graph showing an example of the hysteresis characteristic of a magnetic medium, Fig. 2 is a waveform diagram to explain the distortion of the reproduced signal caused by the hysteresis, and Fig. 3 is a system diagram showing one embodiment of the present invention. , FIG. 4 is a waveform diagram for explaining the operation of the present invention, and FIG. 5 is a system diagram showing another embodiment of the present invention. 1: reproduction signal source, 2: amplifier, 3: imitation circuit. Figures 1 and 2 *3 Figure 4 Ticket 5 Figure

Claims (1)

[Claims] 1. A simulated circuit having a core, a magnetic field generating means consisting of a coil wound around the core, and a magnetoelectric transducer arranged electromagnetically coupled to the magnetic field generating means, and a simulated circuit created using this simulated circuit. A subtraction circuit that calculates the difference between the distorted signal and the input signal of the simulated circuit is inserted into the recording system or the reproduction system, and the original signal having waveform distortion based on the magnetic hysteresis of the magnetic medium is used as the input signal. input into the simulated circuit,
The material of the core is selected so that its magnetic hysteresis characteristic is approximately equal to the magnetic hysteresis characteristic of the magnetic medium, and the simulated circuit generates the waveform distortion in a simulated manner and superimposes it on the original signal. the distorted signal is created, the difference between the distorted signal and the original signal is calculated by the subtraction circuit, and a signal from which the waveform distortion is removed is obtained from the original signal. playback device.