JPH01140403A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To switch the characteristics of a differentiator by equipping an impedance circuit possessing >=two circuit elements out of a resistance, a capacitor and an inductance, and a switching means for switching the connection of the circuit element. CONSTITUTION:A differentiator 50 is equipped with the impedance circuit which possesses at least two circuit elements out of resistors R11 and R12, a capacitor C11 and an inductance L11 in order to alter the characteristics of the differentiator 50 for a regenerative signal from recording media whose recording densities are different, and the switching means for switching the connection of the circuit elements. Further, out of the three elements of the resistances R11 and R12, the capacitor C11 and the inductance L11, only the one element of the resistances R11 and R12 are switched. Thus, the characteristics of the differentiator 50 can be switched.

Description

[Detailed Description of the Invention] E-Industrial Application Field] The present invention relates to a magnetic disk device used in electronic computers, computer peripheral terminals, and the like.

[Prior Art] For example, a conventional magnetic disk device shown in Japanese Patent Application Laid-Open No. 62-3411 is shown in FIG. This will be explained using FIG. 4 and FIG. 5. FIG. 3 is a diagram showing the configuration of a conventional magnetic disk device, and FIG. 4 is a diagram showing the circuit configuration of the differentiator 3 in FIG. 3. Further, FIG. 5 is a diagram showing output waveforms of each part in FIG. 3.

A conventional magnetic disk drive includes an amplifier 1 that amplifies a signal reproduced by a magnetic head from a recording medium, a low-pass filter 2 that removes unnecessary high frequency components from the output of the amplifier 1, a differentiator 3, and a zero-crossing point of the output of the differentiator 3. It is comprised of a pulse generator 4 that detects and outputs it as a read data pulse.

Since the recording density of the recorded signal is different near the outer periphery of the disk (outer track) and near the inner periphery (inner track), the differential characteristics of the differentiator 3 are changed in order to read the recorded signal appropriately. There is a need to. Therefore, the differentiator 3 is connected to a microcomputer 5 which outputs a control signal for switching the characteristics of the differentiator depending on the position of the magnetic herad. In FIG. 5, the signal (C
) is the output signal of amplifier 1, and signal (d) is the output signal of differentiator 3
The signal (e) is the output signal of the pulse generator 4.

Next, the operation of the above conventional example will be explained. As shown in Figure 3,
A signal reproduced from a recording medium by a magnetic head (not shown) is amplified by an amplifier 1, and unnecessary high frequency components are removed by a low-pass filter 2.

The signal from which high frequency components have been removed by the low-pass filter 2 is differentiated by a differentiator 3, as shown in FIG. 5(d), and further transmitted to a pulse generator 11. The pulse generator 4 is
Detecting the zero cross point from the waveform of signal (d) in Figure 5,
Output as read data pulse train. At this time, the characteristics of the differentiator 3 depend on whether the control signal from the microcomputer 5 is input to the resistor 3A or 3B of the differentiator 3 in FIG. , an inner track circuit 31 consisting of an inductance L1, or an outer track circuit 32 consisting of a resistor R2, a capacitor C2, and an inductance L2.

[Problems to be Solved by the Invention] Since the conventional magnetic disk drive is configured as described above, there is a problem in that when changing the characteristics of the differentiator 3, it is necessary to change all three elements: resistance, capacitor, and inductance. There was a point.

This invention was made to solve the above-mentioned problems, and provides a magnetic disk device in which the characteristics of a differentiator can be changed by changing only one of the three elements of resistance, capacitor, and inductance. is intended to provide.

[Means for Solving the Problems] A magnetic disk device according to the present invention includes a magnetic head that reproduces information recorded on a recording medium by scanning the recording medium, a differentiator that differentiates the signal, and a differentiator. The differentiator is equipped with a pulse generator that detects the zero-crossing point of the differential waveform, converts it into a pulse train of read data, and outputs the pulse train. The impedance circuit has at least two or more circuit elements of a resistor, a capacitor, and an inductance, and a switch means for switching the connection of the circuit elements.

[Operation] The recording medium is, for example, a floppy disk, and the magnetic head scans the recording medium along tracks on the recording medium, for example, an inner track and an outer track,
The recording densities of ↑n information recorded on the inner track and outer track, which are used to read information stored on a recording medium, are generally different.

A signal corresponding to information stored on a recording medium reproduced by a magnetic head is amplified by an amplifier, unnecessary high frequency components are removed by a low-pass filter, and then differentiated by a differentiator.

A differentiator consists of a set of transistors, a capacitor, an inductance, and a resistor connected in series between each emitter of the transistor. The source and drain of the field effect transistor are connected between both terminals of the resistor through another resistor with a different resistance value, and the field effect transistor acts as a switch by applying a current to the gate, and the two terminals mentioned above are connected. Switch the resistance.

When the recording density of information is different, the differentiator must change the gain characteristics and frequency characteristics according to the recording density. For example, a control device composed of a microcomputer etc. Alternatively, when scanning on the inner track, the outer 1
- Detect whether the rack is being scanned, and change the characteristics of the differentiator to match the recording density by switching whether or not to apply current to the field effect transistor of the above-mentioned differentiator accordingly. Change to

[Embodiment] A first embodiment showing a magnetic disk device according to the present invention
This will be explained using FIGS. 2(a) and 2(b) and FIG. 3.

FIG. 1 shows a differential circuit of a magnetic disk device according to the present invention. 2(a) and 2(b) respectively show the frequency characteristics of the differentiating circuit shown in FIG. 1, and FIG. Due to the switching operation of FET51, R1
1 shows changes in characteristics depending on the resistance when R21 is switched from R21 to R21. FIG. 2(b) shows the phase characteristics, and shows the change in characteristics depending on the resistance when R11 or R11 shown in FIG. 1 is switched to R21. FIG. FIG. 3 is a diagram showing a magnetic recording and reproducing method.

The magnetic disk device according to the present invention includes an amplifier 1 for amplifying a signal reproduced by a magnetic head from a recording medium, a low-pass filter 2 for removing unnecessary high frequency components from the output of the amplifier 1, a differentiator 50, and a differentiator 50 for controlling the output of the differentiator 50. It consists of a pulse generator 4 that detects a zero cross point and outputs it as a read data pulse. A microcomputer 5 is connected to the differentiator 50, which outputs a control signal for switching the characteristics of the differentiator depending on the position of the magnetic head.

At tj in FIG. 1, the output of the low-pass filter 2 is input to input terminals 50A and 50B of a differentiator 50.

Input terminals 50A and 50B are each connected to a transistor T.
Connected to the bases of R1 and TR2. A capacitor C1l, an inductance Lll, and a resistor R11 are connected in series between the emitters of each transistor TRI and TR2. A resistor R2 is connected between both terminals of the resistor R11.
The drain and source of a field effect transistor (FET 51) are connected via 1. A terminal 50C is connected to the source of the FET 51 via a resistor R22 to the microcomputer 5, and a control signal from the microcomputer 5 is input thereto.

The operation of the above embodiment will be explained below. A signal reproduced by a magnetic head (not shown) is amplified by an amplifier 1, unnecessary high frequency components are removed by a low pass filter 2, and its output is input to a differentiator 50. Further, the output of the differentiator 5o is input to the pulse generator 4 and converted into a pulse train of read data. The abnormal operation is the same as in the conventional example. The microcomputer 5 controls the position of the magnetic head and sends different control signals when the magnetic head (not shown) scans on the inner track of a recording medium such as a floppy disk and when it scans on the outer track. Output.

The microcomputer 5 outputs a control signal to the source of the FET 51 via the terminal 50, thereby controlling the FET 5.
Operate the switch configured in step 1. The resistor is switched to either one of the resistor R11 and the resistor R21 by turning ON and OFF the switch constituted by the FET 51.

By changing the resistance value of the differentiator 50, the characteristics of the differentiator 50 are set so that the characteristics of the differentiator 50 become 1&appropriate when the magnetic head scans the inner track and outer track of the recording medium, respectively. At this time, the differentiator 50
The characteristic is given by the following formula and the gain characteristic is 6'''' 2 (T-) Rc+2Re However, in Fig. 1, Rc is the load resistance of transistors TRI and TR2, and Re is the resistance between the collector and emitter of transistors TRI and TR2. (not shown) and 2 indicate the impedance of the differentiator 50.

It depends on the resistance.

As shown in Figure 2, by changing the resistance value of the differentiator, the gain characteristic (a) and phase characteristic (b) can be changed depending on when the magnetic head scans the inner track and outer track on the recording medium. Change.

Note that although the above example shows an example in which only the resistance value was changed, the characteristics of the differentiator can be similarly changed by changing the capacitor and inductance! It goes without saying that it can be done.

[Effects of the Invention] As described above, according to the present invention, the magnetic spatula 1. When tl scans on the inner track and outer track of the magnetic recording body, only one of the resistor, capacitor, and inductance is switched, so tl scans on the inner track and outer track, 8 In order to obtain the optimum characteristics of the differentiator, the number of components is reduced compared to the conventional example in which two sets of impedance circuits each consisting of three elements, a resistor, a capacitor, and an inductance, are selectively switched and connected. be able to. Further, by reducing the number of parts, variations in the characteristics of the differentiator are reduced, and a highly accurate one can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a differentiator circuit of a magnetic disk drive according to the present invention, FIGS. 2(a) and (b) are diagrams showing frequency characteristics of the differentiator shown in FIG. 1, and FIG. 3 is a diagram showing a general 4 is a diagram showing the configuration of a differential circuit in a conventional magnetic disk device, and FIG. 5 is a diagram showing each part of the magnetic recording and reproducing method shown in FIG. 3. FIG. 3 is a diagram showing an output waveform. In the figure, 1 is an amplifier, 2 is a low pulse filter, 3.5
0 is the differentiator, 4 is the pulse generation date, 5 is the microcomputer, C1l is the capacitor, Lll is the inductance,
R11 and R21 are resistors, 51 is FET, TRI, TR
2 is a transistor. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A magnetic head that reproduces information recorded on the recording medium by scanning the recording medium, a differentiator that differentiates the signal, and a differentiator that detects the zero-crossing point of the differential waveform of the differentiator and converts it into a pulse train of read data. In a magnetic disk drive equipped with an output pulse generator, the differentiator includes at least two circuit elements of a resistor, a capacitor, and an inductance for changing characteristics of the differentiator with respect to reproduction signals from recording media with different recording densities. 1. A magnetic disk drive comprising: an impedance circuit having at least one impedance circuit; and switch means for switching connections between the circuit elements.