JPH0359803A - Write circuit for floppy disk device - Google Patents

Abstract

PURPOSE:To reduce a peak shift and to write write signals of respective period with optimum resolution by varying a write current writing a delay signal into a floppy disk in accordance with the output level of a current signal. CONSTITUTION:A holding circuit 3 outputs the current signal 11 holding the value of a discrimination signal 10 when it is pulse-inputted by the delay signal 9. A flip flop 4 switches the output state of respective output terminals Q and the inverse of Q and supplies the current to a coil C1. The write current at that time is decided by a variable constant current circuit 6 in accordance with the current signal 11. Thus, resolution when the signals of respective period are written can be improved, and the peak shift can be reduced by supplying the write current optimum for the period of the write signal to the magnetic head 12.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a floppy disk device that is a peripheral recording device of a host system such as a computer system, and particularly to a floppy disk device that records information provided from a host system on a floppy disk. The present invention relates to a write circuit.

[Conventional technology]

Conventionally, in the write circuit of this type of floppy disk device, the magnitude of the write current supplied to the magnetic head in order to record information on the floppy disk is determined by a signal indicating information provided from the host system (hereinafter referred to as a write signal). It was considered to be a constant regardless of the period of the signal (referred to as a signal).

The intensity of the successive output of information written on the floppy disk is proportional to the intensity of the write current. Write current O
If the output is gradually increased from 100 to 100, the intensity of successive outputs will gradually increase, but once a certain write current value (peak current value) is exceeded, it will become smaller (see Figure 3).
. This is due to magnetic saturation in the gap portion of the magnetic head and demagnetization effect due to magnetization within the floppy disk, and the above-mentioned peak current value differs depending on the frequency of the write signal.

[Problems to be Solved by the Invention] The writing circuit of the conventional floppy disk device described above is
Since the magnitude of the write current was assumed to be constant regardless of the period of the write signal, there is a drawback that the output strength of the write signal for each period differs, resulting in different resolutions. Another disadvantage is that this also increases the peak shift of information written on the floppy disk.

SUMMARY OF THE INVENTION An object of the present invention is to provide a write circuit for a floppy disk device that has a small peak shift and can write write signals of each cycle with optimum resolution.

[Means to solve the problem]

The write circuit of the floppy disk device of the present invention writes a write signal, which is a pulse train sent from a host system, onto the floppy disk. a delay circuit that branches and outputs a delayed signal in two directions after a time; a writing means that inputs one of the branched delayed signals and writes the signal to a floppy disk; and a branched delay circuit. a period discrimination circuit which inputs the other of the signals and outputs a discrimination signal indicating the interval between the pulse trains in the signal; and a period discrimination circuit which inputs the delayed signal and the discrimination signal and is triggered by the pulse in the delayed signal, a hold circuit for outputting a current signal holding the output level of the discrimination signal; and a variable constant current circuit that makes the write current variable, and the delay time in the delay circuit is such that when the period discrimination circuit outputs a discrimination signal that discriminates the write signal, the pulse train on which the discrimination was performed is This is what is output.

[Function] The write current when a delayed signal is written to the floppy disk is variable depending on the interval of pulse trains in the delayed signal, that is, the period, so writing is performed at the peak current value for each frequency. be able to.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the main part configuration of one embodiment of the writing circuit of the floppy disk device of the present invention, and FIG.
FIG. 3 is a time chart showing the operation of each part in the embodiment shown in the figure, and FIG. 3 is a diagram showing the saturation characteristics of the magnetic head.

This embodiment includes a period discrimination circuit 1, a delay circuit 2, a hold circuit 3, a flip-flop 4, a write circuit 5 serving as a write means,
It is composed of a variable constant current circuit 6 and a magnetic head 12, and inputs a write signal 7, which is a pulse train sent from a host system (not shown), and a clock 8 generated inside the floppy disk device, and operates the magnetic head 12. It supplies a write current to the internal coil C1.

MF most commonly used in floppy disk devices
In the M recording method, the pulse train interval is IT, 1.5T,
There is a period of 2T. The period determination circuit 1 is configured as a counter and inputs a write signal 7 and a clock 8.
A determination signal 10 that is a status signal that determines how many cycles of the clock 8 the interval between pulse trains in the write signal 7 corresponds to, and indicates this by the level of the output level.
Output. The delay circuit 2 receives the write signal 7 and outputs it as a delayed signal 9 after a predetermined delay time. The hold circuit 3 inputs a delay signal 9 and a discrimination signal 9, is triggered by a pulse in the delay signal 9, and outputs a current signal 11 indicating a supplied current according to the interval of the current pulse train according to its output state to a variable constant current circuit 6. Output to. In the flip-flop 4, the delay signal 11 is inputted to the clock terminal (CLK), and the output terminal (Q,
Change the output state of Q). The write circuit 5 includes two transistors Ql and Q2 and a damping prevention resistor R1.
The bases of the transistors Ql and Q2 are respectively connected to the Q and Q output terminals of the flip-flop 4, and the collectors are connected to the coil C1 in the magnetic head 12.
Both ends and the emitter are connected to a variable constant current circuit 6, respectively. A resistor R1 is provided between the collectors of each transistor Ql and Q2. The variable constant current circuit 1 includes each transistor Q1. It incorporates a variable resistor (not shown) provided between the emitter of Q2 and ground, and its resistance value is switched according to the output state of the current signal 11. A supply voltage Vc applied from the outside is applied to the central part of the winding of the coil C1.
is applied, so in this embodiment, each transistor Ql depends on the output state of the flip-flop 4.
, Q2 is activated to determine the direction of the write current, and the magnitude of the write current is determined by the resistance value of the variable low current circuit.

Next, the operation of this embodiment will be explained with reference to FIGS. 2 and 3.

When the write signal 7 is input from the host system, the delay circuit 2 outputs the delay signal 9 and the period discrimination circuit 1 outputs the discrimination signal 10 to the hold circuit 3, respectively, as described above. Discrimination signal 1
0 is "if the pulse interval is IT (period number 2F)"
When the pulse interval is 27 (frequency IF), the signal becomes "H" level.The delay time in the delay circuit 2 is determined by the pulse train in which the discrimination is performed in the status signal of the discrimination signal 10. is determined in consideration of the discrimination time t1 of the cycle discrimination circuit 1, and is set to 1.5T in this embodiment. A current signal 11 that holds the value of the discrimination signal 10 when a pulse input is made.
Output. The flip-flop 4 switches the output state of each output terminal Q, Q every time a pulse is inputted using the delay signal 9 to supply current to the coil C1, but the write current at this time is based on the current signal 11. This is determined by the variable constant current circuit 6 according to the above.

Figure 3 shows the saturation characteristics of the magnetic head at each frequency IF and 2F, with the horizontal axis representing the write current and the vertical axis representing the successive output. If the write current is I2 or 1K2, and the frequency is 2F, the write current will be 11 or -11, which can be the peak current value at each frequency, and with a constant write current ■3. Compared to the conventional one,
We were able to significantly improve continuous output.

In this embodiment, pulse intervals of IT and 2T are used, and the discrimination signal indicates the pulse interval in a binary state, but there are also pulse intervals of 1.5T. Of course, the period discriminating circuit may be one that indicates these pulse intervals in a three-valued state, and it is clear that the effects of the present invention are independent of the recording method and the pulse intervals resulting therefrom.

[Effects of the Invention] As explained above, the present invention improves the resolution when writing signals of each cycle by supplying a write current to the magnetic head that is optimal for the cycle (frequency) of the write signal. , and the peak shift can be reduced. Therefore, it is possible to improve the reliability of the produced floppy disk device.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the main part configuration of an embodiment of the present invention, Fig. 2 is a time chart showing the operation of each end of the embodiment shown in Fig. 1, and Fig. 3 is the saturation characteristic of the magnetic head. FIG. 1...Period discrimination circuit, 2...Delay circuit, 3...Hold circuit, 4...Flip-flop 5...Write circuit , 6...
...Variable constant current circuit, 7...Write signal, 8
...Clock, 9...Delay signal,
10...Discrimination signal, 11...Current signal, 12...Magnetic head.

Claims (1)

[Claims] 1. In a write circuit of a floppy disk device that writes a write signal, which is a pulse train sent from a host system, to a floppy disk, the write signal is input, and after a predetermined delay time, a delay circuit that branches and outputs delayed signals in two directions; and inputs one of the branched delayed signals;
a writing means for writing the signal onto a floppy disk; inputting the other of the branched delayed signals;
a period discrimination circuit that outputs a discrimination signal indicating the interval between pulse trains in the signal; and a current that receives the delayed signal and the discrimination signal, is triggered by a pulse in the delayed signal, and maintains the output level of the discrimination signal at that time. a hold circuit that outputs a signal; and a variable circuit that inputs the current signal and changes a write current for writing the delayed signal to the floppy disk by the writing means in accordance with the output level of the current signal. and a constant current circuit, and the delay time in the delay circuit is such that when the period discrimination circuit outputs a discrimination signal that discriminates the write signal, a pulse train on which the discrimination has been performed is outputted. Features a writing circuit for a floppy disk device.