JPS6260750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a head load control system for a flexible disk drive, and more particularly to a head load control system in which a magnetic head is loaded onto a floppy disk medium by a rotating cam coupled to an electric motor.

Conventionally, in this type of flexible disk device, the magnetic head was loaded by a cam connected to an electric motor, and a constant current was passed through the electric motor to rotate the cam, but regardless of the shape of this cam, the magnetic head However, it has the disadvantage that the speed at which it is loaded onto the medium is fast.

To avoid this, a coil spring or an air damper was used in the electric motor to suppress the speed at which the head touches (loads) the medium, but when a coil spring is used, the load due to the coil spring becomes large and the magnetic head It is necessary to flow a large current in the load state, and when an air damper is used, the cost is high and a place for mounting the air damper is required.

In order to eliminate such drawbacks of the conventional art, the present invention switches the current flowing to the motor using an electric circuit using clock pulses and makes the duty variable, thereby changing the actual current value, that is, changing the torque of the motor. The purpose is to slow down the speed at which the head contacts the medium.

According to the present invention, a floppy disk device having a mechanism for bringing a magnetic head into contact with a magnetic medium includes a timer circuit that generates a plurality of gate signals in response to a head load signal, and a timer circuit that generates a plurality of gate signals in response to the gate signals of the timer circuit. A headload control system is obtained, comprising an oscillator capable of varying the duty of clock pulses oscillated at regular intervals, and an electric motor operating the contact mechanism in response to the output signal of the clock pulses of the oscillator.

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

FIG. 1 shows a loading mechanism for a magnetic head in a floppy disk device according to an embodiment of the present invention.
In FIG. 1, a head load mechanism 10 has an electric motor 11 directly connected to a rotating cam 12, and this rotating cam 12 has two head load cams 13, 14.
arm 1 of the magnetic head holder 15, 16.
5', 16'. The magnetic head holders 15 and 16 are provided with magnetic heads 17 and 18, respectively, and are adapted to come into contact with the floppy disk medium depending on the rotational position of the head load cams 13 and 14.

This magnetic head loading mechanism 10 loads the magnetic head 1 when the rotary cam 10 is in the rotating state shown in FIG. 2a.
7 and 18 are at a position apart from the floppy disk 20, and the magnetic heads 17 and 18 are in a position in which they are in contact with the floppy disk 20 when the rotating cam 10 is rotated as shown in FIG. The magnetic heads 13 and 14 connect the head load cam 1 between both positions.
It is configured to slide along cam surfaces No. 3 and 14. As the electric motor 11 of the magnetic head loading mechanism 10 is rotated by a control signal to be described later, the magnetic heads 17 and 18 move from the rotating position shown in FIG. 2a to the rotating position shown in FIG. 2b. Regardless of the cam shape of the head load cam, the floppy disk medium is contacted at a high speed, so there is a risk of damaging the medium or the magnetic head itself.

FIG. 3 shows a circuit in a head load control system according to an embodiment of the present invention. In Figure 3,
The method of controlling the electric motor of the head load mechanism is a timer circuit 21 which is driven by a head load signal a and generates a plurality of head load signals c, d, and e.
and a D/A converter 22 that generates an analog signal according to the digital signals of the plurality of head load signals c, d, and e, and a D/A converter 22 that generates an analog signal at regular intervals according to the analog control voltage of the D/A converter 22. It has an oscillator 23 that changes the duty of the clock pulse to be output, and a drive circuit 24 that receives the clock pulse g of the oscillator 23 and drives the motor 11.
This method allows the speed of contact with the surface to be controlled.

Next, the operation of the embodiment will be explained with reference to the time chart shown in FIG. In the headload control circuit, when the headload signal a is input to the timer circuit 21, the timer circuit 21 sequentially generates a fixed time signal, that is, a timer signal c, a timer signal d, and a timer signal e. This timer circuit 21
Since clock signal b, which is a high-frequency pulse for timing, is input, timer signals c, d, and e having a predetermined time width are generated based on this clock signal as a reference. For example, this timer circuit 21 outputs the timer signal c from time _t0 to _t1 ,
A timer signal d is generated from time _t1 to _t2 , and a timer signal e is generated from time _t2 to _t3 . D/A converter 2
1 converts the signal from the timer circuit 20 into an analog signal in response to the signal. That is, the D/A converter 21 generates _{a 1-} level analog signal for the timer signal c, a _2- level analog signal for the timer signal d, and _{a 3-} level analog signal for the timer signal e. is generated and output as an analog control voltage.

Next, the duty variable oscillator 23 has each level ₁ ,
When _{the second} and _third analog signals are supplied, the duty (Duty), that is, the pulse width of the pulses generated at regular intervals is changed based on these signals, and the pulses are sent out as clock pulses g. This clock pulse g corresponds to _one level of control voltage, i.e.
It has a high duty and a pulse width D _H between time t ₀ and _{t 1} , has a pulse width D ₅₀ for a _2- level control voltage (time t ₁ and t ₂ ), and has _{a 3-} level control voltage ( has a pulse width D _L for the period t ₂ to _{t 3} ). When the clock pulse g is input, the drive circuit 24 supplies a drive current h to the motor 11 in response to the clock pulse g.
Drive the electric motor to rotate. In other words, in this drive circuit 24, the drive current becomes large for the clock pulse g having a high duty (D _H ), and the drive current becomes slightly large for the clock pulse g when the duty is set slightly higher than 50% (D ₅₀ ). Furthermore, when the duty is set to 50% or less (D _L ), the drive current becomes slightly smaller than the clock pulse g. Therefore, the electric motor 11
is rotated in accordance with the drive current, and in response the magnetic head is brought to a speed i at which it approaches the floppy disk 20.

As a result, in this method, the head loading time can be increased and the speed at which the head contacts the head medium can be decreased.

As described above, in this embodiment, the section is divided into three sections and the duty is similarly set in three sections, but the duty setting value for each section depends on the characteristics of the motor and the coupling method with the magnetic head. You can set it freely. Furthermore, the unloading of the head can be set in the same way, and the drive current can be set in the same way as when loading the head.

As explained above, the present invention utilizes the duty of clock pulses to control the electric motor that drives the magnetic head, thereby safely loading and unloading the head at an extremely low cost and without complicating the mechanism. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a head load mechanism used in the present invention, FIG. 2 is a diagram showing a cam state of the head load mechanism, FIG. 3 is a diagram showing a head load control system according to an embodiment of the present invention, and FIG. is a diagram showing the time chart. 10... Head load mechanism, 11... Electric motor,
12... Rotating cam, 13, 14... Head load cam, 15, 16... Head holder, 15', 1
6'... Protrusion, 17, 18... Magnetic head, 20
... Floppy disk, 21 ... Timer circuit, 22 ... D/A converter, 23 ... Variable duty oscillator, 24 ... Drive circuit.

Claims (1)

[Claims] 1. In a floppy disk device having a mechanism for bringing a magnetic head into contact with a magnetic medium, there is a timer circuit that generates a plurality of gate signals in response to a head load signal, and a timer circuit that oscillates at regular intervals in response to the gate signals of the timer circuit. 1. A headload control system comprising: an oscillator capable of varying the duty of a clock pulse; and an electric motor operating the contact mechanism in response to an output signal of the clock pulse of the oscillator.