SU1606997A1 - Magnetic recording device with dynamic bias - Google Patents

Abstract

The invention relates to instrumentation, in particular to a magnetic recording technique, and can be used in household magnetic recording apparatus. The purpose of the invention is to improve the recording quality by reducing the nonlinear distortion and structural noise of the magnetic recording carrier by maintaining the symmetry of the half-wave current of the high-frequency biasing while dynamically adjusting its amplitude. This is achieved by introducing a second notch filter 5 connected through the first variable resistor 6 to the base of the regulating bipolar transistor 7, the junction resistance of the collector which is the load of the voltage doubled rectifier 11. The transistor 7, in conjunction with the rectifier 11, operates as a controlled variable voltage / high frequency component of the write signal / resistor connected to an alternating current circuit of high frequency biasing / HPC / parallel magnetic recording head, and this resistor has equal resistance values for equal amplitudes of half waves the high frequency signal, therefore, the current of the ICP changes when it is dynamically regulated symmetrically and there is no constant component in the recording signal causing a parasitic signal. magnetization and increase in carrier structural noise. Reducing the bias current when high frequency components are present in the recording signal leads to a bias optimum bias towards the high frequencies, which during playback increases the output from the carrier and reduces the level of nonlinear distortion, thereby improving the recording quality. 1 il.

Description

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(21) 4412189 / 24-10

(22) 04.19.88

(46) 11/15/90. Bü No. 42 (75) A.T. Koz Vin

(53) 681.84 (088.8)

(56) USSR Author's Certificate No. 1218420, cl. G 11 B 5/027, 5/03, 1988..

(54) DEVICE OF MAGNETIC RECORDING WITH DYNAMIC SWITCHING

(57) The invention relates to instrumentation, in particular to a magnetic recording technique, and can be used

in household magnetic recording equipment. The purpose of the invention is to improve the recording quality by reducing the nonlinear distortion and structural noise of the magnetic recording carrier by maintaining the symmetry of the half-waves of the high-frequency bias current while dynamically adjusting its amplitude. This is achieved by introducing a second notch filter 5, connected through the first variable resistor 6 to the base of the regulating bipolar transistor 7, the transition resistance; whose emitter is

is the load of the rectifier 11 with a doubling of the voltage. The transistor 7, in conjunction with the rectifier 11, operates as a controlled variable voltage (high-frequency component of the recording signal) resistor connected to the high-frequency bias (ACh) alternating current circuit parallel to the recording magnetic head, and this resistor has equal resistance values for equal amplitudes of half waves of a high frequency signal, therefore, the current of the ICP, when it is dynamically controlled, is symmetrical and the constant signal does not appear in the recording signal, causing parasitic w magnetization of noise and increased structural support. Decreasing the current. Magnetization in the presence of high frequency components in the recording signal leads to a bias optimum biasing towards the high frequencies, which during playback increases the output from the carrier and reduces the level of nonlinear distortion, thereby improving the recording quality. 1 Il.

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The invention relates to instrumentation, in particular, to a technique of magnetic recording, and can be used in household equipment magnetic recording sound.

The purpose of the invention is to improve the recording quality by reducing the nonlinear distortion and structural noise of carrying magnetic recording due to the preserved NIN symmetry of the half-waves of the high-frequency biasing current while dynamically controlling its amplitude

The drawing shows a block diagram of the proposed device.

The device contains serially connected input bus 1, wuxi: record 2 driver, first notch filter 3. and recording magnetic head 4 connected by another view switch to the common bus, and also connected in series and connected between the second recording magnetic head 4 ; notch filter 5. and the first variable resistor 6, the middle pin of which is connected to the control electrode (base) of the bipolar co-transistor 7, the emitter of which is connected to the common bus through the resistor 8; and and magnetization (GSP), the output connected via a second variable resistor 10 to the recording magnetic head 4 and to the input of the rectifier 11. with a doubling of the voltage, the output connected to the collector of the transistor 7. The rectifier 11 with a doubling of voltage contains included between its input and the common bus are connected in series the first capacitor attor 12, the first diode 13 connected in the forward direction, the cathode connected to the output of the rectifier, and the second capacitor 14, while the second diode 15 is connected by the anode to the common bus and the cathode- to the anode of the first diode 13.

The proposed device works in the following way.

The input audio signals from input bus 1 are amplified in recording amplifier 2, which also provides the same recording frequency in the recorded frequency range, and through the first notch filter 3 (for the frequency of the high-frequency biasing signal - HFI), a recording magnetic head 4 is received , and also through the second notch

filter 5 (also for the frequency of the HF signal) and the first variable resistor 6 to the base of the regulating transistor 7.

With small recording levels (less than -20 dB from the Nominal value), as well as with nominal and close to it recording levels, but in the absence of a high signal in the recorded signal, often the voltage of the recorded signal on the magnetic head 4 and the base of the transistor 7 is small and its not enough to open the transistor. The signal of the VCHP supplied to the head 4 from the output of the SHG 9 through the second variable (current regulating) resistor 10 with a higher level than the recorded sound signal is practically not supplied to the base of the transistor 7 because it is suppressed by the second notch filter 5, When closed transistor 7 its resistance to the collector-emitter junction, which is load for rectifier 11, is large, while the rectifier input resistance is large and not shunting recording magnetic head 4, in which the high-frequency current is magnetised is maintained optimal for maximum impact on the magnetic tape medium frequencies (for 400 or 1000 Hz).

With the appearance of a high frequency in the recording signal with a level of -15 dB and higher than the nominal value, the audio frequency voltage on the magnetic head 4 increases due to an increase in its impedance at high frequencies. Transistor 7 begins to open up the positive half-periods of the high-frequency components of the recorded signal, and the higher the frequency and the level of the high-frequency components (the regulation starts at frequencies higher than 3000 ... 5000 Hz), for which high-frequency components separated from a real sound signal, unlike low-frequency components, will be symmetrical in amplitude and envelope duration for both half-waves. The collector-emitter junction resistance of an open transistor 7 decreases, thus decreasing the load and input resistance of the rectifier 11, which begins to shunt the recording magnetic head 4 at the frequency of the HPS signal, which leads to a decrease in current

magnetization. A decrease in the current of the CPP occurs symmetrically for both half-wave signals and the more, the higher the frequency and level of the high-frequency components in the recorded signal. The bipolar transistor 7, together with the rectifier 11c doubling the voltage, operate as a variable-voltage controlled resistor connected to the AC circuit of the HFP (parallel to the recording magnetic head) and in series with the second variable current-regulating resistor 10, and this controlled resistor has equal values of resistance for equal to the amplitude of the half-wave of the high-frequency signal. The capacity of the second capacitor 14 is chosen; There is a much larger capacitance of the first capacitor 1.2 (0.033 microfarads and 1000 pF, respectively); therefore, the regulation is practically made at the frequency of the high-frequency biasing signal. (usually in the order of 100 kHz). A decrease in the bias current in the magnetic head leads to a shift in the optimum magnetization and the high frequency side, which increases the recording-reproduction channel at recording levels of -10, -15 dB from the nominal value. Resistor 8 selects the minimum possible values of the HF current to obtain the most uniform frequency response at recording levels of -5 ... O dB. The predicted device could be used to introduce dynamic bias in tape recorders with fixed bias, and this is included between the common busbars and connection point A (see drawing)

15

Claims (1)

Invention Formula Magnetic recording device with dynamic magnetizationM | containing 20 Next Commonly connected input bus, recording amplifier, first notch filter and recording magnetic head connected by Another output to common bus, first alternating resistor connected by single output to common bus, medium output to high-frequency erasing and sub-magnetizing generator to transistor control electrode whose output In the future, (during playback), the second variable resistor. tape output at high frequencies and reduces non-linear distortion, which improves the recording quality. Thanks to the fact that the current of the ICP in the recording head 4 changes, with its dynamic control. symmetrically for both half-waves in the recording signal, there is no constant component causing parasitic magnetization and an increase in the carrier structural noise, Using the first variable resistor 6, the device sets the required threshold, i.e. a certain level of alternating voltage at the base of the transistor 7, when it begins to open and decrease at this time the current of the ICP in the magnetic head. This threshold is chosen based on obtaining the most uniform amplitude-frequency characteristic (AFC). 6997 recording-playback channel at a recording level of -10, ..- 15 dB of nominal value. The resistor 8 selects the minimum possible amount of HF current to obtain the most uniform frequency response at a recording level of -5 ... O dB. The predicted device can be IQ used to introduce dynamic-r. Who is magnetized in tape recorders with a fixed bias, while it is included between the common bus and the connection point A (see drawing). 15 Invention Formula Magnetic recording device with dynamic biasM | containing a serially connected input bus, a write amplifier, a first notch filter and a recording magnetic head connected by another output to a common bus, a first variable resistor connected by a single output to a common bus, an average output to the control electrode of the transistor, a high-frequency erasure generator and sub-magnetisation whose output five 0 five 0 characterized in that in order to improve the recording quality by reducing the nonlinear distortion and structural noise of the magnetic recording carrier by maintaining the symmetry of the half-wave current of the high-frequency biasing during dynamic amplification of its amplitude, the inputs connected to the magnetic head of the first injector are inserted into it filter and to the second output of the second variable resistor; the second notch filter and rectifier with voltage doubling, output connected to a transistor whose emitter is connected through a common bus resistor, and the output of the second notch filter is connected to another terminal of the first variable resistor.