DE2124378C3 - Method for supplying an information signal to an electromagnetic transducer and arrangement for applying the method - Google Patents

Description

an even harmonic of des; Preload .5 «* g £ KSeB for magnetic recording

indicates that the low-frequency information * sg gJf BereSs soft? ie

tion signal of the second harmonic of the VorgSSnfS ^^ SS? Se of

f £ where α «is the feSÄ because the difference is reached.

\ pS and "« das Das ™ * £ %% ^% * t

distinguishing signal is and a Stron, η B ^^^ eSdef 15Ϊ Ä

/ - 7 fcos ω «+ s (ü cos 2ω /) premagnetization used. For this purpose, for example

/ - / "(cosci + s {t) cos2a> t) _wise I ^ _{the a} B _{f the core jm & AinclM winding}

is fed to the electrically conductive element, such a high-frequency bias signal ge characterized in that 3 »JJ ^ dJl ^ _T » föSSZ & ££ ^

I s (t) K 1 '4 can be applied.

. ' ^Wl From the published Dutch patent application

4. Arrangement for using the method message 66 12 895 is a recording method according to claim 1, characterized by a 35 known, which is based on the P ^nM ° ^me "^" Jj ' ^da J .. ^ ⁱⁿ high-frequency oscillator (1), which is an electrical AC current fed through a conductor at a high voltage pre-paring signal with the frequency ω, ren frequencies in a thin layer on the surface and a modulator (3) for modulating the surface of the conductor flows. This phenomenon is referred to as a first set of terminals as a skin effect. In doing so, the low-frequency information to be supplied to the same electrical current is forced out of the conductor Conductor-generating electrical signal with the frequency πω is greatest. There is also the largest RNA ( "even), in particular 2 to be ω, which produces a-magnetic fields, and these are addressed in the correct phase relationship 45 outwardly phase rotator (3). Which in the above publication is derived from the high-frequency oscillator (3). proposed converter now basically consists of

an electrically conductive element terminating in a tip, which in a magnetizable recording medium to change the magnetization 50 of a ·. or specific part of the same is arranged. The low-frequency information signal and the high-frequency bias signal are added

The invention relates to a method of being fed together to the electrically conductive element. Excitation of an electromagnetic transducer from Since the frequency of the information signal in general

Skin effect type with an electrically conductive EIe- 55 in common is so low that for the signal field ment to change the magnetization of a past- the desired field configuration does not occur If the correct part of a magnetizable record is to be made, the low-frequency signals in the high-frequency medium must be converting a frequency signal into a high frequency signal. Transformed into the aforementioned Low frequency information signal publication has been proposed, a modulation and a high frequency bias signal is generated using methods to obtain low frequency information and jointly convert the electrically conductive egg signals into higher frequency ones. Will ment. the information signal but any auxiliary

The definition and reproduction of digital, analog signal modulated, then the desired malogen or audio signals with the help of an electromagnetic field configuration are not generated because the magnetic transducer on a magnetizable "envelope" of the recording medium fed to the conductive element is known. One signal should not exactly follow the information signal, shine that there is a multitude of different con

Structures of the required electromagnetic converter of the type mentioned at the beginning

to improve the magnetization recording process significantly by a suitable choice of Frequency of the auxiliary signal ensures that the envelope of the signal supplied to the information signal follows.

This problem is solved in that an auxiliary signal a frequency which is an even harmonic of the bias signal and that the low-frequency information signal is modulated on the auxiliary signal in terms of amplitude.

It should be noted that when modulating the Inforniationssignals on an odd harmonic of the bias frequency is the zero crossings were shifted so that the odd harmonics cannot be used.

For example, provided that ω is the frequency of the bias signal and s (f) is the signal to be recorded, a current

/ = / ₀ (cos ωί + s (t) cos 2 ωί) ao

are fed.

The advantage of applying signals in this way is that the frequency of the bias signal is high can be higher and the signal field drops as quickly as the bias field, which is an additional Improvement of the field gradient results. In addition, the auxiliary signal used can be simply Way to derive from the bias signal.

It is preferable to ensure that when a signal of the form described above is fed to the converter,

KOI <

35

is because in this case it turns out that the "envelope" of the information signal is still accurate follows so that no distortion occurs.

It should be noted that the inventive way of supplying signals, for all those electromagnetic Converters is applicable in which the phenomenon of the skin effect is applied to the recording process.

The invention also relates to an arrangement for carrying out the method described above, which arrangement is characterized by a high-frequency oscillator which supplies an electrical bias signal with the frequency ω, and by a modulator for modulating a low-frequency information signal to be fed to a first set of connecting terminals of the same a second set of terminals of the same electrical signal to be fed with the frequency πω (η even), in particular 2 ω, which is derived from the high-frequency oscillator via a phase rotator in the correct phase ratio.

The correct phase ratio in this context means that the phase ratio must be fixed, and in such a way that the outermost values of the even-numbered Hannonian derived with the extreme values or zero points of the bias signal must coincide. It should It is evident that the intended phase relationship is considered in relation to the magnetic field must and not in relation to the current.

An embodiment of the invention is shown in the drawing and will be described in more detail below described. It shows

F i g. 1 shows a block diagram to explain an arrangement serving as an example for use the invention,

F i g. 2 the shape of a bias signal,

F i g. Figure 3 shows the form of a derived signal with a double frequency that is an information signal is modulated on,

F i g. 4 shows the sum of these signals.

In Fig. 1, a bias signal with the frequency ω (Fig. 2) and a signal with the frequency 2 ω are taken from the oscillator 1. In the modulator 3, the information signal j (i) to be recorded is modulated onto the signal with the frequency 2ω. The result is shown in FIG. 3 indicated. The modulated signal (frequency 2ω) and the projection signal (frequency ω) are then fed together to the electromagnetic converter 4.

This is essentially a conductor around which a magnetic field is generated when a current passes through it. When this current is very high frequency, it will flow on the surface of the conductor, which is a phenomenon can be used in magnetic recording of the signal. A converter of the above Art can for example consist of two pole pieces made of magnetizable material, between which is an electrically conductive film that carries the bias and information signals (optionally modulated onto an auxiliary signal) are fed together.

It depends on the converter used, whether there is a phase shift between the magnetic field and the current will occur. If this is the case, a phase rotator 2 must also be added to the circle so that this phase shift is compensated.

What the signal fed to the transducer ultimately looks like is shown in FIG. 4 indicated.

1 sheet of drawings

Claims (1)

see converter gM. A conventional electro - t. OTiptkcher WaoSer is, for example, the magnetic Patent claims: SdefauTeS core made of ferromagnetic ma- * l. Method for exciting an electromagnetic "£ ** XSTÄSÄ ta a high frequency signal converted JJ ~ X ₁ ^ 5SSi _in ¹ SS _i Sffi niederfrequenteslnformationssjpalundemhoch- "^^^ ο ™ flows through the winding verurfrequentes V" M "MPd erzeug j £ 5 SdSer SS, magnetic flux in the core, and currency together the etektnsch conductive element ~ g ^e JJS _sning ^ _n signal through the winding