RU2069886C1 - Method of recording information - Google Patents

Abstract

FIELD: applied magneto-optics; read-out/record devices. SUBSTANCE: method is based upon relative movement of magnetic carrier and recorder, and on local effect of variable magnetic field onto magnetic carrier, which effect is formed by recorder. Local influence is made by at least with single pair of unlike pulses of magnetic field applied in perpendicular to plane of the carrier. Time interval between pulses of the pair is much more less then their duration. EFFECT: improved efficiency of operation. 8 cl, 3 dwg

Description

 The invention relates to the field of applied magneto-optics and is industrially applicable in devices for recording / reading onto magnetic media.

Known thermomagnetic method of recording information on a magnetic medium, including the relative movement of the magnetic medium and the recording device, as well as local exposure to the magnetic medium with a magnetic field generated by the recording device [1]
The disadvantage of this analogue is the low contrast and brightness of the image when visualizing magnetic recording due to the small angle of rotation of the plane of polarization in a thermomagnetic information carrier.

The prototype of the proposed method is a known method of recording information on a magnetic medium, including the relative movement of the magnetic medium and the recording device, as well as local exposure to the magnetic medium with an alternating magnetic field generated by the recording device [2]
The disadvantage of the prototype is the low contrast and brightness of the image when visualizing magnetic recording, since the magnetic medium is magnetized during recording in its plane, and when visualizing the presence of a beam splitter leads to the loss of more than 75% of the light and its scattering.

 The technical result achieved by using the claimed invention is to increase the contrast and brightness of the image when visualizing magnetic recording.

 This result is achieved by the fact that in the known method of recording information on a magnetic medium, including the relative movement of the magnetic medium and the recording device, as well as local exposure to the magnetic medium with an alternating magnetic field generated by the recording device, local exposure to the magnetic medium is carried out by at least one pair bipolar magnetic field pulses applied perpendicular to the plane of the carrier, and the time interval between the pulses of the pair is many enshe their duration.

In particular, the durations of τ ₊ and τ _- pulses of opposite polarity and the period of their following T are changed according to a given law.

 In particular, local influence on the magnetic medium with an alternating magnetic field is carried out by bringing it into contact with a recording device in the form of a magnetic stamp drawn from permanent magnets, or in the form of a needle made of soft magnetic material that is passed through a coil, and at least one is fed into the coil one pair of bipolar current pulses. In this case, rectangular, trapezoidal or triangular current pulses of alternating polarity are fed into the coil, and these pulses can have the same shape.

The achievement of the technical result indicated above is due to the fact that when an alternating magnetic field is exposed to a magnetic carrier at intervals of time between adjacent pulses of opposite polarity, they are much shorter than their duration, recording is carried out in the form of two adjacent domains whose magnetic moments are oriented along the normal to the plane carrier. During visualization, such a record looks like a sequence of adjacent dark and light strokes on a "gray" background. Two such strokes on a "gray" background, as experience shows, are much easier to distinguish than each of them separately located. This provides an increase in the contrast and brightness of the image. If it is necessary to encode the recorded information, the pulse durations of opposite polarity τ ₊ and τ _- and the period T of their repetition are changed according to a given law. If it is necessary to obtain a large number of identical records, for example, in the manufacture of tickets, the recording is carried out by creating a magnetic contact between the information carrier and the stamp typed from permanent magnets. In the event that each recording must be individual, the recording is carried out with a needle of soft magnetic material passed through a coil into which bipolar current pulses are supplied.

 The invention is illustrated by drawings. Figure 1 and 2 show two variants of a block diagram of a visualizer, and figure 3 plot of pulses of opposite polarity. The visualizer (figure 1) contains a light source 1, a collimator 2, a polarizer 3, a substrate 4 with a film 5, an analyzer 6 and a lens 7, the last two elements can be interchanged. The film 5 is in magnetic contact with the magnetic medium 8. In the second version of the visualizer (figure 2), a mirror 9 is used, which allows more convenient to arrange the elements.

The method is implemented as follows. The magnetic medium 8 and the recording device (not shown in FIGS. 1 and 2) are brought into relative motion. Information is recorded at the time when the recording device and the medium 8 are in magnetic contact by local and short-term exposure to the medium 8 with a magnetic field. When using a magnetic stamp, it is brought into contact with the carrier 8. When using a needle, its end is moved along the surface of the carrier, while applying current pulses to the coil (Fig. 3). The durations of τ ₊ and τ _- pulses of opposite polarity in a pair determine the length of the “light” and “dark” strokes during visualization, and the period T is the recording period. The distribution of contrast along the length of the strokes depends on the shape of the current pulses. The recorded information is visualized using one of the visualizers (figures 1 and 2). A plane-polarized light beam at the output of the polarizer 3 falls on the substrate 4, passes through it and the film 5, and is reflected from its free surface onto which a reflective coating can be applied. With a double passage of light through the film 5, the polarization plane rotates, and the direction of rotation depends on the direction of magnetization of the local sections of the film 5. The distribution of magnetization in the film 5 is determined by its distribution in the magnetic carrier 8.

 Example 1

Used the circuit shown in figure 1. An incandescent bulb connected to a direct current source was used as a light source 1. We used film polarizer 3 and analyzer 6, as well as spherical lenses as collimator 2 and lens 7. We studied the possibility of recording onto magnetic medium 8 in the form of magnetic rubber using a magnetic stamp. The visualizer used an epitaxial film 5 of a ferrite garnet of the composition (Y, Lu, Bi) ₃ (Fe, Ga) ₅ O ₁₂ deposited on a gadolinium-gallium garnet substrate with orientation (III).

 Example 2

The same as in example 1 except that the information was recorded on a magnetic medium 8 in the form of a video tape using a steel needle equipped with a coil, which was connected to a source of rectangular current pulses of opposite polarity (figure 3) with τ ₊ and τ _- 10 μs and T 180 μs.

 Example 3

 The same as in example 2, except that the pulses had a triangular shape.

 Example 4

 Same as in Example 2, except that trapezoidal pulses were used.

 Example 5

The same as in 1, except that when writing τ ₊ = τ _{- they} changed from 10 to 100 μs, and the repetition period T from 80 to 1000 μs.

Claims (8)

 1. The method of recording information on a magnetic medium, including the relative movement of the magnetic medium and the recording device, as well as local exposure to the magnetic medium with an alternating magnetic field generated by the recording device, characterized in that the local impact on the magnetic medium is carried out by at least one pair of unipolar pulses a magnetic field applied perpendicular to the plane of the carrier, and the time interval between the pulses of the pair is much less than their duration. 2. The method according to claim 1, characterized in that the durations of τ ₊ and τ _- pulses of opposite polarity and the period of their following T change according to a given law.  3. The method according to claim 1, characterized in that the local influence on the magnetic carrier with an alternating magnetic field is carried out by conducting it in magnetic contact with a recording device in the form of a magnetic stamp drawn from permanent magnets.  4. The method according to claim 1, characterized in that the local influence on the magnetic medium with an alternating magnetic field is carried out by bringing it into magnetic contact with a recording device in the form of a needle of soft magnetic material, which is passed through a coil, and at least one is fed into the coil a pair of bipolar current pulses.  5. The method according to claim 4, characterized in that the rectangular current pulses of alternating polarity are fed into the coil.  6. The method according to claim 4, characterized in that the trapezoidal current pulses of alternating polarity are fed into the coil.  7. The method according to claim 4, characterized in that the triangular current pulses of alternating polarity are fed into the coil.  8. The method according to PP. 4 to 7, characterized in that alternating polarity current pulses that have the same shape are fed into the coil.

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