JPH04263103A - Magnetic recording/reproducing device - Google Patents

Abstract

PURPOSE:To prevent generation of a steep current waveform when switching a magnetic head current by a rectangular wave of digital signal and prevent crosstalk at a low-frequency region and reduction in S/N ratio according to harmonics at a PCM band. CONSTITUTION:A rectangular wave which is modulated by a digital processing portion 2 is converted to a curved waveform by a sinusoidal waveform conversion portion 11. A recording which is similar to analog recording is performed to a tape by an amplifier 12 and a magnetic head H based on current of the curved waveform. A signal which is reproduced by a magnetic head becomes a curved waveform and a rectangular waveform can be demodulated by detecting it with a limiter 5.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is applicable to DAT and digital V
The present invention relates to a magnetic recording/reproducing device that records digital signals, such as a TR, and particularly to a magnetic recording/reproducing device that prevents the occurrence of steep recording waveforms.

0002

[Prior Art] FIG. 7 shows a conventional digital recording device.
The circuit configuration of a magnetic recording/reproducing device for AT is shown. FIG. 7(A) shows a recording system circuit, and FIG. 7(B) shows a reproducing system circuit. In the digital processing section 2, the recording digital signal is 8-10 converted, and this 8-10 converted data is input to the recording amplifier 1. The recording amplifier 1 converts the "0" and "1" signals into positive and negative currents, respectively. Recording is performed from the magnetic head H onto the magnetic tape using a constant current method. In the reproduction operation, the signal read by the magnetic head H is reproduced by the reproduction amplifier 3, the frequency characteristics are corrected by the equalizer 4,
Sent to limiter 5. FIG. 8 shows waveforms of recording signals and reproduction signals in the conventional magnetic recording and reproducing apparatus. FIG. 8(A) shows 8-10 processed by the digital processing unit 2.
The recording waveform of converted 10-bit data is shown. In the case of DAT, NRZI (No.
Return to Zero Inverse)
It is modulated according to the rules of As shown in Figure 8 (A), this modulation method reverses the current by amplifier 1 for each "1" signal of the 8-10 converted data, and records the tape with different magnetic poles. It is something to do. Therefore, a reproduced signal from a tape recorded using this method theoretically has a differential waveform as shown in FIG. 8(B). When this differential waveform passes through the equalizer 4, a curved waveform substantially in the same state as that of the integrated waveform is obtained. FIG. 8(C) shows this waveform. This waveform is then detected by the limiter 5 at a predetermined threshold level, and as shown in FIG.
A square wave equivalent to that shown in (A) is demodulated.

0003

[Problems to be Solved by the Invention] However, in an actual device, when writing is performed using the magnetic head H, the current is switched by the amplifier 1 based on the square wave shown in FIG. The current flowing through H has a waveform shown in FIG. 8(D). That is, due to the inductance of the magnetic head H, the current switching section becomes in the same state as being differentiated, and a current with a steep waveform as shown in (a), (b), and (c) flows. Based on this steep current, magnetic recording remains on the magnetic tape. Therefore, the reproduction signal from the magnetic tape is different from that shown in FIG. 8B, and the magnetic recording made by the steep current is reproduced as is. As a result, the following problems arise. Figure 8(A)
Recording using a square wave as shown in FIG. 1 is performed not only in the PCM recording area of several MHz but also in the recording of pilot signals in the ATF band where a low frequency of approximately 100 kHz is used. Therefore, when the frequency characteristics are corrected by the equalizer 4 and the gain in the high frequency region is increased, the steep high frequency reproduced waveform shown in FIG. 8(D) is emphasized, causing overshoot and ringing in the low frequency signal, and distortion. This results in accelerated adjacent crosstalk and head magnetization. Also, in the PCM recording area, harmonics due to the steep waveform shown in FIG. 8(D) crosstalk to adjacent tracks,
This will cause deterioration of S/N. The present invention solves the above-mentioned conventional problems, and aims to provide a magnetic recording and reproducing device that can prevent the generation of steep recording current due to square wave recording and eliminate the negative effects of this steep recording current. .

0004

[Means for Solving the Problems] A magnetic recording and reproducing device according to the present invention includes a digital processing unit that modulates recorded data into a predetermined square wave, and a conversion unit that converts this square wave into a curved wave with smoothed amplitude changes. The device is characterized in that it is equipped with an amplifier that sends the converted curved wave to a magnetic head and records it on a magnetic tape.

[0005]

In the above means, the square wave of the digital signal, which has been subjected to 8-10 conversion, is converted by the converter into a current having a curved waveform. Recording is performed on the magnetic head by the current according to this curved waveform, and the recording at this time becomes magnetic recording in almost the same state as analog recording using the curved waveform. Therefore, in the reproducing system, the curved waveform output described above is obtained, and the square wave can be demodulated by passing this waveform through a limiter and performing detection at a predetermined threshold level.

[0006]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings of FIGS. 1 to 6. FIG. 1 shows a circuit diagram of a magnetic recording/reproducing apparatus having a basic configuration according to the present invention, and FIG. 1(A) is a block diagram showing a recording system, and FIG. 1(B) is a block diagram showing a reproducing system. In FIG. 1, numeral 2 is a digital processing section, and 11 is a sine wave converting section for forming a curved waveform. The reproduction system is the same as the conventional example shown in FIG.

FIG. 2 shows waveforms at various parts in the magnetic recording/reproducing apparatus. FIG. 2(A) shows the digital processing section 2.
A square wave modulated by DA is shown as an example.
NRZI modulated signal for T is shown. By converting this signal by the sine wave converter 11, as shown in FIG.
A curved waveform (approximately sinusoidal waveform) as shown in (B) is obtained. This curved waveform is obtained by converting the square wave shown in FIG. 2(A) so that the rising or falling portion becomes a smooth curve. In the amplifier 12, a recording operation similar to analog recording is performed by the magnetic head H based on the curved waveform shown in (B), and magnetic recording is performed with a magnetic flux density proportional to the change in the amplitude of the current shown in FIG. 2 (B). . Therefore, the reproduction output from the reproduction system basically has the same waveform as shown in FIG. 2(B). By passing this waveform through the limiter 5 and detecting it at a predetermined threshold level, a square wave as shown in FIG. 2(C) is demodulated. In this way, magnetic recording is performed using a curved waveform as shown in FIG. 2(B).
A steep waveform due to square wave recording as shown in D) does not appear, and therefore problems caused by crosstalk and harmonics in the low frequency range due to the steep waveform can be solved. Note that since it is possible to record and reproduce any waveform as long as it is a square wave, it is not limited to NRZI-converted data as shown in FIG. Even modulated data can be recorded and reproduced.

Next, the specific configuration of the sine wave converter 11 will be explained. FIG. 3 shows a first embodiment of the specific configuration of the sine wave converter. This configuration includes a 4-bit register 15 into which digital data is input, and a determining unit 16 that determines the period of a square wave of 4-bit data shifted by 1 bit by the 4-bit register 15 based on the 4-bit detection width. and a switching section 17 that selects and outputs one of the four frequencies f1, f2, f3, and f4 based on the discrimination result by the discrimination section 16. These frequencies f1, f2, f3, and f4 can be obtained, for example, by dividing the system clock. In this embodiment, using the 4-bit register 15 as described above,
The period of the square wave is determined by the determination unit 16 using a width of 4 bits. The reason why the period is determined using a width of 4 bits is because it is assumed that NRZI-converted data is used. It is. That is, in the NRZI-converted data, the longest string of "0000" or "1111" is 4 bits, so a maximum of 4 bits of data is required to determine the period of the square wave.

As shown in FIG. 4A, each bit number of the NRZI-converted data is temporarily set to 1, 2, and 3 from the left.
, 4,... This data is stored in 4-bit register 1.
5, the discriminating section 16 performs discriminating with a width of 4 bits while shifting the square wave one bit at a time, and determines the cycle of the square wave that includes the first 1 bit of the 4-bit width. Then, the frequencies of f1, f2, f3, and f4 are switched based on the period of the square wave that includes the first 1 bit of the width of 4 bits. For example, as shown in FIG. 4(B), from the first to the fourth
When determining based on the bit width, the period of the square wave that includes the first bit is the shortest, so the determining unit 16
The frequency of f1 is selected by the switching unit 17.
frequency is output. Then shift by 1 bit and 2
Judging by the width of the 5th to 5th bits, the period of the square wave that includes the first bit (second bit) is still the shortest, so frequency f1 is selected (see Figure 4).
C)). Similarly, as shown in FIG. 4(D), the frequency f1 is continuously selected until the third to sixth bit widths are determined. Next, as shown in FIG. 4(E), in the determination using the 4-bit width from the 4th to the 7th bit, the period of the square wave that includes the first 1 bit is the second length from the shortest (2 bit length). Therefore, in this case, the discrimination section 16 and the switching section 17 select the frequency f2. Similarly, the frequency f2 is selected up to FIG. 4(G). When the frequency obtained by shifting one bit at a time as described above is selected and switched bit by bit, the result is shown in Figure 4 (
The same curved waveform as shown in FIG. 4(A) is obtained by converting the rectangular waveform of FIG. 4(A) into a curved line. By detecting this curved waveform with a limiter, a demodulated square wave as shown in FIG. 4(I) is obtained.

FIG. 5 shows a second embodiment of the specific configuration of the sine wave converter 11. In this embodiment as well, the digital data is sent to the 4-bit register 15, the 4-bit width data is shifted bit by bit, and the discrimination unit 18 discriminates the cycle of the square wave that includes the first 1 bit of the 4-bit width. be done. Then, in the voltage level setting section 19,
Four levels of voltages V1, V2, V3, and V4 are set according to the period of the waveform that includes the determined first bit. When the 8-10 converted data is NRZI modulated, the longest waveform is up to 4 bits as described above, so the voltage setting may be done in four stages, and the discrimination may be made in a 4-bit width. Based on this determination, the voltage is set as shown in FIG. 6(B). In other words, when determining the period of the waveform that includes the first bit from the first to fourth bits of the square wave shown in FIG. 6(A), this is the shortest, so the voltage V1
is set. When shifting to the third bit, V1 continues to be output in the same way. Next, for the fourth to seventh bit widths, the period of the waveform including the first bit is 2.
Since the width is bit width, the voltage is set to V2. This continues while shifting up to the 9th bit. In determining the 10th to 13th bit width, the first 1
Since the period of the square wave including bits is 3 bits long, voltage V3 is set. By continuing this process, a voltage that changes stepwise as shown in FIG. 6(B) can be obtained. In the FM modulator 20, the fundamental wave is frequency-modulated using the voltage shown in FIG. 6(B), and a modulated waveform shown in FIG. 6(C) is obtained. This is divided by the frequency divider 21 and shown in FIG.
A curved waveform shown in (D) is obtained. This curved waveform is equivalent to making the square wave shown in FIG. 6(A) into a smooth curve. By detecting this curved waveform with a limiter, a square wave as shown in FIG. 6(E) is demodulated.

In the embodiment shown in FIG. 5, FM modulation is applied using a set voltage, but oscillation is performed by a VCO (voltage controlled oscillator) based on this set voltage, or by a PLL circuit using a VCO. It may also be caused to oscillate. Although a frequency divider is provided in FIG. 5, the frequency divider 21
Recording is performed as is with the waveform shown in Figure 6(C) without frequency division by You can also pass this through a limiter.

0012

As described above, according to the present invention, it is possible to prevent the generation of current with a steep waveform as shown in FIG. It is possible to prevent a decrease in S/N. In addition, since the recording signal is recorded using the same recording method as conventional analog recording, the NR
It is not necessarily necessary to generate waveforms such as ZI modulation.

[Brief explanation of the drawing]

FIGS. 1A and 1B are block diagrams showing circuits of a recording system and a reproducing system of a magnetic recording and reproducing apparatus according to the present invention.

2A to 2C are waveform diagrams showing waveforms of various parts in the circuit of FIG. 1;

FIG. 3 is a circuit block diagram of a first embodiment showing a specific example of a sine wave converter.

4(A) to (I) are waveform diagrams showing waveforms of each part of the circuit of FIG. 3; FIG.

FIG. 5 is a circuit block diagram of a second embodiment showing a specific example of a sine wave converter.

6A to 6E are waveform diagrams showing waveforms at various parts of the circuit of FIG. 5;

FIGS. 7A and 7B are block diagrams showing recording and reproducing system circuits of a conventional magnetic recording and reproducing device.

[Fig. 8] (A) to (D) are waveform diagrams showing waveforms of each part in the circuit of Fig. 7.

[Explanation of symbols]

H Magnetic head 2 Digital processing section 3 Playback amplifier 4 Equalizer 11 Sine wave conversion section 12 Recording amplifier

Claims (1)

[Claims] Claim 1: A digital processing unit that modulates recorded data into a predetermined square wave, a conversion unit that converts this square wave into a curved wave with smoothed amplitude changes, and a magnetic head that transmits the converted curved wave. 1. A magnetic recording/reproducing device comprising: an amplifier for transmitting and recording onto a magnetic tape;