SU1200330A1 - Flux-sensitive piezoinduction head - Google Patents

Description

The invention can be used in magnetic recording equipment for reproducing information. The purpose of the invention is to expand the bandwidth of the head. For this, the oscillation source is made in the form of a piezoelectric transducer 1 located in a conducting half-wave glass 2

with an acoustic hub 3. The oscillations of the piezoelectric transducer are transmitted to the micropipe 4, which is part of the circuit with a varying cross section. The resulting emf is directly proportional to the magnetic field of the magnetic tape at the playback point. Placing the piezoelectric transducer in a double metal screen - glass and body - reduces the noise level and prevents penetration into the noise reproduction circuit of the device itself. The source of oscillations is connected to the body through needle holders mounted on an acoustic neutral. The implementation of the microwire in the form of a printing coil, the plane of the turns of which is perpendicular to the longitudinal axis of the concentrator, allows to increase the sensitivity of the head. 1 h. the item of f-ly, 5

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The invention relates to instrumentation, in particular to magnetic recording equipment, and can be used to reproduce information.

The purpose of the invention is to expand the bandwidth of the head, as well as an increase in sensitivity.

FIG. 1 shows a head; in fig. 2 microwire.

The proposed flow-sensitive head consists of a piezoelectric transducer 1 located inside a conductive half-wave non-magnetic cup 2 with an acoustic concentrator 3. The piezo transducer has an acoustic contact with the bottom of the glass. The tip of the concentrator is mechanically connected with the central part of the coil, or microwire 4, reinforced between the conductive supports 5 with contacts 6 and with non-metallic struts 7, with the plane of the turns of the coil perpendicular to the longitudinal axis of the acoustic concentrator. A half-wave tumbler and an acoustic hub are mechanically connected with a ring 8 fixed in a common metal case — a screen 9 on three pairs of needle holders 10, which are at an angle of 120 ° to one another. With contacts 6, raised. data to the supports 5, removed the useful EMF. Supports 5 are electrically isolated from the housing - screen 9 using non-metallic struts 7. When the device is in operation, contacts 11 are connected to the output of a generator exciting a piezoelectric transducer, and contacts b to the preamplifier input. The microwire can be made in the form of a printed circuit (Fig. 2) made on the substrate 12, the insulator 13, E-contacts of the printed coil 14.

When a sinusoidal or pulsed voltage is applied to the piezoelectric transducer electrodes, the loudspeaker-glass-to-hub transducer system is excited at the resonant frequency and reports mechanical oscillations to the microwire or the printing coil. The oscillating coil, or microwire, is part of a circuit with a variable cross section. The resulting emf is directly proportional to the frequency and amplitude of the oscillations of the microwire and the magnetic field of the magnetic tape at the point of playback of the recording.

The head provides increased accuracy (fidelity) of reproducing the magnetic field of a magnetic tape, has a high threshold of sensitivity due to the low level of noise. The noise level is reduced due to low resistance (several

Ohm) of the measuring circuit and the fact that the piezoelectric transducer is placed in a double metal screen and sufficiently removed from the measuring circuit by means of an acoustic hub. The first screen is a half-wave glass, the second is a metal case. The double shielding of the piezo transducer and the separation in space of the excitation circuits and the reproduction of the magnetic recording exclude the device itself from interfering with the noise reproduction circuit arising in the piezo transducer continuous excitation mode mainly due to the high alternating voltage applied to the piezo transducer electrodes with a frequency equal to the signal frequency.

In the case of a pulsed excitation mode of a piezotransducer, electrical interference occurs in the form of electromagnetic oscillations due to the inverse piezoelectric effect of polarizing the crystal during resonant oscillations of the speaker system also with a frequency equal to the signal frequency. The use of an acoustic concentrator increases the sensitivity of the head, since small amplitude oscillations of the piezocrystal transform into significant mechanical vibrations of the tip of the concentrator, and hence the microwire.

Claims (2)

Claim 1. A flow-sensitive piezo-induction head comprising a body and an oscillation source, characterized in that, in order to expand the head bandwidth, a microwire is inserted into it, mounted on the body supports, an acoustic hub connected to a conducting half-wave glass, needle holders, and the oscillation source is made in the form of a piezoelectric transducer, with a half-wave glass located inside the body and connected with it through needle holders mounted on an acoustic neutral in the cavity of a half-wave glass located on a piezoelectric transducer and an acoustic microwire hub connected to the middle portion thereof. 2. Head π. 1, characterized in that, in order to increase its sensitivity, the microwire is made in the form of a printing coil, the plane of the turns of which is perpendicular to the longitudinal axis of the acoustic hub. 1200330