DE1177204B - Magnetic head for reading broadband signals - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Class: H 03 k German KL: 21 al-37/20

Number: 1177 204

File number: E 23165IX c / 21 al

Filing date: July 6, 1962

Opening day: September 3, 1964

For many purposes of magnetic recording, especially magnetic recording of Television signals, it is desirable that the magnetic heads can process a wide frequency band.

It is known to divide a wide frequency band into two frequency ranges before recording and then record the areas in parallel tracks. So there are two recording heads provided, which are each optimally designed for the partial frequency range, and two are also used for reading Magnetic heads required.

It is also known to divide the partial frequency ranges into two successive ones in the running direction of the magnetic tape and feed magnetic heads associated with the same track. Due to the small distance the successive working air gaps can be read with a single conventional magnetic head take place.

If, however, broadband signals are to be reproduced with a single magnetic head, then result difficulties arise with regard to the dimensioning of the magnetic head. An essential factor in the development of read heads, which determines the reproduction of high frequencies, is the fact that a considerable Part of the flow closes through the air behind the working gap and thus not the interspersed winding attached to the core. If you reduce the dimensions of the head, so can the frequency from which the magnetic resistance of the core material is greater than that of the Way of air is to be exalted. But then there is the difficulty of making enough turns to accommodate the core in order to generate a sufficiently large voltage at low frequencies.

The invention is based on the problem of solving these difficulties encountered during scanning remove. The invention consists in that the core, the pole pieces of which are responsible for the high frequency components Form a dimensioned working air gap, a winding for the decrease of low frequency components as well as a second winding with separate connections near the pole tips for the removal of the carries high frequency components.

The invention enables the use of a relatively large head on which a sufficient Number of turns for the low frequencies can be applied, but that too The reading of high frequencies is allowed because the high frequencies make the winding for the low frequencies not reach, where they close over a short path around the pole tips, at the second Winding can be removed.

Magnetic head for reading broadband signals

Applicant:

Electric & Musical Industries Ltd.,

Hayes, Middlesex (Great Britain)

Representative:

Dr.-Ing. B. Johannesson, patent attorney,

Hanover, Göttinger Chaussee 76

Named as inventor:

Donald Peter Franklin, Wells (Great Britain)

Claimed priority:

Great Britain July 8, 1961 (24 815)

According to one embodiment of the invention, the core is made of low-loss ferrite on which thin pole pieces made from a highly permeable material, especially from the one called Alfenol

the well-known aluminum-iron alloy are. The winding for the low frequencies is applied to the core body, and the winding for the higher frequencies, the core is embedded as close as possible to the pole tips. The PoI shoes preferably form an uninterrupted front surface and bridge one half of the Winding embedded in the core. This results in only a slight shunt for short wavelengths formed, and it is possible to have the winding very close to the pole tips for the higher frequencies to be arranged where otherwise a winding cannot be attached. The current in each winding can, if desired, be processed in separate amplifiers designed for the appropriate frequency band will.

The invention is explained in more detail below with reference to two exemplary embodiments.

In Fig. 1, T denotes a magnetic tape which may be arranged in a magnetic tape device.

In operation, the tape T runs over a playback head H which consists of a ferrite core composed of two similar parts Y and Y ' . The two core halves have cap-like pole _{pieces P 1} and P ₂ made of alfenol, the one

form a narrow air gap G between them.

In the core below the pole shoes there are windings W ₁ and W ₉

for the high frequencies

409 659/162

left, while the windings L ₁ and L, for the low frequencies are arranged on the main body of the core. The output of the low-frequency windings is fed to the amplifier ^, then mixed with the output of the high-frequency winding, and there is common amplification in A. The amplifier Α _Λ is designed so that differences between the frequency response of the low and high frequencies of the head H compensates will.

F i g. Figure 2 shows a similarly constructed playback head with a horseshoe-shaped core.

If separate windings are assigned to the high and low frequency components in this way, the self-capacitance of each low-frequency winding is of less importance, so that a larger one Part of the winding space can be filled and only the desired total thickness of the wound Head sets a limit on the height of the winding. The low frequency windings can be divided into sections be divided so that the self-capacitance is further reduced, and a section of each low-frequency Winding, preferably the one closest to the high-frequency windings, can have its own Get connections and form a separate output for the middle frequencies to be amplified.

The invention is not only as described in a playback head, but also in a Pick-up head applicable.

Claims (4)

Patent claims: 1. Magnetic head for reading broadband signals recorded in a track, characterized in that the core (Y, Y '), the pole pieces of which form a working air gap (G) dimensioned for the high frequency components, has a winding (L ₁ , L.,) for the decrease of low frequency components as well as a second winding (W ₁ , W ₂ ) with separate connections near the pole tips for the decrease of the high frequency components. 2. Magnetic head according to Claim 1, characterized in that the pole pieces forming the working air gap (G) consist of caps (P) which are placed on the surface of the core (Y, Y ') facing the recording medium (Γ). 3. Magnetic head according to claim 1, characterized in that the second winding (W ₁ , W ₂ ) is arranged on the pole ends of the core (Y, Y ') below the pole shoes. 4. Magnetic head according to claim 3, characterized in that the halves of the second winding (W ₁ , W ₂ ) facing the pole pieces are embedded in the core (Y, Y '). Considered publications:
German Patent No. 714 123;
Swiss patent specification No. 329 794. 1 sheet of drawings 409 659/162 8. 64 ® Bundesdruckerei Berlin