JPH04502976A - Improvement of magnetic recording method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] °Improvement of magnetic recording method” The present invention relates to a magnetic recording system. Conventional magnetic recording uses a, c, and bias. It was accompanied by a different recording method. These a, c, and bias are high amplitude, high frequency signals. It is added to the signal to be recorded. The purpose of this bias signal is to The goal is to reduce or eliminate distortion due to hysteresis in the air medium. audio and In video magnetic recording, the desired information signal linearizes the distortion problem encountered. Use this additional high frequency, high amplitude bias signal (a, c, bias) to recorded on magnetic tape.

a, c. The disadvantage of the bias method is that high frequency signals cannot be recorded effectively. Ru.

According to the invention, the generation of the signal to be recorded is inversely proportional to the transfer function of the recording process. a magnetic field that includes modifying the signal to be used, and adding the modified signal to the recording head of the recording device. A method of air recording is provided.

The slope of the transfer function of the recording process changes with fluctuations in the signal level, and this The method includes modifying the signal separately for different signal levels.

The presence of harmonics in the modified signal is important, and these harmonics are absorbed by the recording head. This method reduces the phase lead of the harmonic with respect to its frequency. We are preparing for

According to the invention, there is further provided input means for accepting the signal to be recorded; means for modifying the signal to be inversely proportional to the transfer function of the recording process; and a recording device. for magnetic recording, comprising means for adding the modified signal to the recording head of Equipment is provided.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings. In the attached drawings, Figure 1 shows the relationship between recording and recorded waves drawn on a linear scale.

FIG. 2 shows the transfer function of the recording process plotted on a logarithmic scale.

Figure 3 also shows the relationship between the signal input and the magnetic flux of the recording head, which is drawn on a logarithmic scale. Indicates the number of reverse transfers.

FIG. 4a shows the signal to be recorded in the form of a sine wave.

Figure 4b shows the modified signal.

Figure 4c shows the modified signal of Figure 4b separated into harmonics.

FIG. 5 is a block diagram of a circuit for implementing the method of the invention.

FIG. 6 is a circuit diagram for implementing the method of the invention.

Referring to the drawings, the present invention has a record of 3. l:, when done without bias The basic idea is to exclude the unique distortions that appear. This characteristic is related to the magnetic flux to be recorded. It is a nonlinear relationship between the recorded magnetic fluxes, and is approximated by a cubic relationship. child The relationship is shown in Figure 1 and is drawn on a linear scale.

Figure 2 shows a similar relationship, but drawn on a logarithmic scale. Nonlinearity in this relationship The gender can be explained as follows. That is, the first 16 dB of the input signal On the other hand, the output signal rises in a relationship of the third power. Continuation of the input signal by 4 dB On the other hand, the output signal rises to the fifth power of the input. Furthermore, the next 20 data of the input signal In Sibel, the output signal increases linearly with the input signal. Then magnetic saturation stay up.

As mentioned above, the transfer function of the recording process does not exhibit any hysteresis. , always takes a single value. The output always takes the same value for a given input signal strength. The previous history of the signal, i.e. whether it is increasing or decreasing. 6, this single value law holds true for all magnetite materials. These are the results from the initial remanent magnetization curves.

Traditionally, the use of a, c, and bias techniques for magnetic recording has allowed for high frequencies under low strain conditions. wave performance is achievable, although insufficient, and is achievable, albeit under high distortion conditions. It was possible to achieve good high frequency performance. Everything for audio and video According to the present invention, magnetic recording accepts this compromise. The signal is modified in a manner that is inversely proportional to the recording transfer function shown in FIG. In this way, by modifying the signal to be recorded and adding the modified signal to the recording head, , essentially distortion-free recording can be achieved without the use of high frequency a, c, bias. becomes possible.

Referring now to Figure 3, the correction function for the recorded signal is plotted on a logarithmic scale. has been done. This function can be explained as follows, i.e., it is a cube root function. The first stage between O (zero) and 50 dB of the force signal, which is the fifth root function, is 50 or a second stage between 70 and 70 dB, and a final stage between 70 and 90 dB, which is the first order. It is a stage. This function is the inverse of the transfer function of the recording process shown in Figure 2. ing.

The signal to be recorded is thus modified to be the opposite of the signal of the transfer function to be recorded. or converted.

For the example, the transfer function of Figure 3 converts the sine wave shown in Figure 4a to Figure 4b. It has the effect of modifying the waveform shown in . According to Fourier analysis, Fig. 4b The waveform of can be described by a series of harmonics. That is, it is the fundamental frequency , and its 3rd, 5th, 7th, etc. harmonics with different relative amplitudes. Ru. This is shown in Figure 4C.

Referring now to Figure 5, in order to make the modification process described above effective, A block diagram is shown. The input signal Vin is added to the modification circuit MOD5. , this circuit converts the signal of the recording transfer function to produce a modified signal Vout. Modify the signal in an inversely proportional manner.

This is added to the recording head drive circuit 50, where Vout is first converted into current. and then converted into magnetic flux to be recorded on a moving tape.

The current from the recording head creates magnetic flux in the head gap, and recording is completed. become.

However, as the frequency increases, the rotational self-capacity of the recording head A phase lag begins to occur in the recording head.

At a certain frequency, the recording head circuit resonates, and the harmonic frequency is around this resonance frequency. As the wave number approaches, the phase of the harmonics at that frequency will become more and more delayed. I'm going to go.

This phase lag progressively delays the higher harmonics of the modified signal. but However, the harmonics of the signal to be recorded must be precisely aligned to their correct positions. Thus, in order to produce low distortion recordings, the modified signal must be The phase of the harmonics is adjusted to compensate for the phase lag caused by the self-capacitance of the recording head. For this reason, it is necessary that the frequency of the harmonics is advanced.

Referring to FIG. 6, a circuit for carrying out the method of the present invention is illustrated. .

This circuit includes a preamplifier stage 71 which receives the signal Vin to be recorded. include. Preamplifier stage 71 uses the input signal to signal modification stage 72. mean.

The signal modification stage 72 includes a control amplifier 721 with an input resistor RO; Resistor RO, in combination with the effective resistance of substages 723 and 724, controls the gate of amplifier 721. control the ins. This substage 723 processes positive signals, while the substage 724 processes negative signals. Tsuku stages 723 and 724 are connected to the line 723a.

723b and 7243.724b form part of a negative feedback loop, respectively.

Each of the substages includes 16 diode stages. secondary stage 723, the diode stages are identified by reference numbers D1 to D16. , the diode stages in substage 724 are referenced D101 to D1. 16.

Each of the diode stages is Conducting at different levels that are controlled.

Each of the diode stages has a bias voltage applied to it. , this diode is made non-conductive until the output voltage from amplifier 721 reaches the specified value. For example, as the output voltage increases from OmV to say 100mV, Therefore, first stage diode D1 starts conducting and increases the gain of amplifier 721. is determined by the ratio of R1 and RO.

As the output voltage from amplifier 721 increases further, diode D2 conducts. The gain is determined by the ratio of the combined resistance of R1 and R4 in parallel and RO. It is decided exactly. This is actually a reduction in gain, and the signal level is still higher than that. As the value increases, the diodes D3, D4, etc. start conducting, respectively, Then, the gain is further decreased. The values of registers R1, R4, R7, etc. are The gain profile of amplifier 721 modifies the input signal Vin in the manner described above. The transfer function of the recording process is chosen to be inverse to that of the recording process.

The output V sod from signal modification stage 72 is passed through conversion register R39 and VR4. and is added to the head drive stage 74. A number of capacitors are connected in parallel with the conversion register. A phase advance stage 73 containing a quantity-resistance network is coupled.

In the phase advance stage 73, the desired frequency range is 6 including nd? Each stage is separated by a 0-phase advance stage that is divided into stages. The stage acts to advance the phase by a small amount, and this advance is Regarding harmonic frequencies. The effect of this is that the inductor 742 of the recording head The aim is to cancel the phase delay caused by the self-capacitance of

This net is the frequency at which the phase of the harmonics of the signal added to the recording head is targeted. The result is that it is held at 90 degrees throughout the microwave.

In the above manner, the harmonics of the modulated signal can be corrected without delay with respect to the fundamental wave. properly positioned.

Modifications and improvements can be made without departing from the scope of the invention. 1,S,, --^-Ichiichi-PcTIGB891oo668 international investigation report GB 89100668 SA　29506

Claims (15)

[Claims] 1. The generation of the signal to be recorded, the generation of said signal inversely proportional to the transfer function of the recording process. of magnetic recording, including correction and addition of the correction signal to the recording head of the recording device. Method. 2. The modification of the above signal includes generating the cube root of the signal to be recorded. The method described in Scope 1. 3. Claim wherein the modified signal comprises generating the fifth root of the signal to be recorded. The method according to scope 1 or 2. 4. The signal is modified by means of a transfer function of different slopes for different signal levels. A method according to any of the preceding claims. 5. The first stage of determining the transfer function of the recording process and the reverse of the determined transfer function. A method according to any of the preceding claims comprising proportional modification of the signal. 6. transforming the phase of the modified signal with respect to the frequency of the harmonics of the signal; A method according to any of the preceding claims. 7. The signal is affected by the phase delay caused by the self-capacitance of the recording head's inductance. 7. The method of claim 6 resulting in a compensatingly advanced phase. 8. The modified signal is fundamental and contains many higher frequency harmonics, each harmonic A method according to any of the preceding claims, wherein the phase of is leading with respect to its frequency. 9. The modified signal contains many components, including the fundamental and many higher frequency harmonics. The phase of each component is determined by the self-capacitance of the inductance of the recording head. 2. A method as claimed in claim 1, proceeding to compensate for the resulting phase delay experienced. 10. Input means for accepting the signal to be recorded, inversely proportional to the transfer function of the recording process means for modifying said signal, and said modified signal in a recording head of a recording device; Apparatus for magnetic recording including means for adding. 11. The means for modifying the signal described above includes a plurality of gain modification stages, each of which Claim 10, wherein the gain modification step is responsive to different signal levels. equipment. 12. Provides a means for advancing the phase of the harmonics of the modified signal with respect to the frequency of the harmonics. 12. The apparatus according to claim 10 or 11, further comprising: 13. The phase advance means described above has a plurality of phase advances each responding to a different frequency band. 13. The apparatus of claim 12, comprising a reading stage. 14. A method of magnetic recording essentially as hereinbefore described with reference to the accompanying drawings . 15. Essentially, magnetic recording as described above with reference to the accompanying drawings. device for