JPH0798802A - Floppy disk drive - Google Patents

Abstract

(57) [Abstract] [Purpose] When the floppy disk is not mounted, even if the magnetic head and mechanical parts come into contact with each other, the magnetic head is prevented from being burnt out without causing a short circuit. [Configuration] Center tap 2 of magnetic head 1 and power supply Vc
A disconnecting means such as a transistor 9 and an FET 10 is connected to the circuit c. The mounting state of the floppy disk is detected by the detection switch, a cutoff signal is generated, and the disconnecting means is operated when the floppy disk is not mounted to cut off the current from the power supply Vcc to the magnetic head 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a floppy disk device used as an external storage device such as a personal computer or a word processor.

[0002]

2. Description of the Related Art In a conventional floppy disk device, as shown in FIG. 7, a center tap 2 of a magnetic head 1 is directly connected to a power supply voltage Vcc.

[0003]

By the way, in the conventional floppy disk drive, generally, as shown in the partially cutaway side views of FIG. 8 and FIG. 9, the first magnetic head 1a is the tip of the carriage main body 50. The second magnetic head 1b is fixed to the inside of the portion, and the second magnetic head 1b is fixed to the inside of the tip of the arm 51 rotatably connected to the carriage body 50. A load is applied to the arm 51 by the head load spring 52 so that the magnetic disk 55 of the floppy disk 54, which is a recording medium, can be stably sandwiched by the first magnetic head 1a and the second magnetic head 1b. There is. When the floppy disk 54 is attached / detached, as shown in FIG. 8, the magnetic disk 55 is rotated upward together with the arm 51 against the elasticity of the head load spring 52 so as not to contact the second magnetic head 1b. There is. When the floppy disk 54 is loaded, the arm 51 and the second magnetic head 1b rotate downward due to the elasticity of the head load spring 52 as shown in FIG. The two magnetic heads 1a and 1b are sandwiched between the magnetic heads 1a and 1b to enable reading or writing.

Now, as shown in FIG. 8, when the floppy disk 14 is attached or detached, the arm 51 and the second magnetic head 1b are rotated upward, and the terminals 4 other than the center tap 2 of the second magnetic head 1b, Alternatively, when a part of the coil or the like comes into contact with the top cover 53 or the like which is grounded to the ground to cause a short circuit, a current of (power supply voltage / head internal resistance) flows through the magnetic head 1b, and the head internal resistance is 5 to 30.
Since it is Ω, it is several hundred mA when the power supply voltage is 5V.
Excessive current flows. As a result, the magnetic head 1b is burned and the power supply voltage is lowered. Further, due to the above problems, the gap between the terminals 4 and the like of the magnetic head 1b and the head cover 53 cannot be narrowed, so that there is a problem that there is a limit to the reduction in thickness of the entire apparatus. On the other hand, also in the system in which the first magnetic head 1a side is rotated downward to attach / detach the floppy disk 54, there is a similar problem with the base plate.

The present invention solves the above-mentioned conventional problems and protects the magnetic head from burning, and also makes it possible to reduce the thickness of the entire apparatus. The purpose is to provide.

[0006]

The technical means of the present invention for achieving the above object is to detect a mounting state of a floppy disk and a magnetic head when the floppy disk is not mounted by the detection of the detecting means. It is provided with an interrupting means capable of interrupting the power supply voltage supplied to the center tap.

Another technical means of the present invention for achieving the above object is to detect a mounting state of a floppy disk, and to detect the detection state of the floppy disk after the spindle motor starts rotating when the floppy disk is not mounted. , 0
It is provided with an interrupting means capable of interrupting the power supply voltage supplied to the center tap of the magnetic head except for the period from the timing of 500 ms to the stop of the spindle motor.

A transistor, an FET, or an analog switch can be used as the connection / disconnection means in each of the above technical means.

[0009]

According to the present invention constructed as described above, the disconnecting means cuts off the power supply voltage supplied to the center tap of the magnetic head by detecting the non-mounted state of the floppy disk by the detecting means. Even if the magnetic head and the grounded part such as the top cover contact at the time, there is no electrical short circuit,
It is possible to prevent an excessive current from flowing through the magnetic head. Further, this makes it possible to narrow the gap between the magnetic head and the top cover and the like as compared with the related art.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram of an essential part showing a floppy disk device according to an embodiment of the present invention. FIG. 2 is a circuit diagram of an essential part showing a floppy disk device according to another embodiment of the present invention. FIG. 4 is a circuit diagram showing a cutoff signal generating circuit used in the floppy disk device of each of the above embodiments.

As shown in FIG. 1, the center tap 2 of the coil of the magnetic head 1 is connected to the power supply Vcc via a transistor 9 which is an intermittent means. A read / write signal and an erase permission signal are applied to the coil of the magnetic head 1 from the head amplifier 7 and the transistor 8 of the read / write circuit 6 via the read / write terminals 3 and 4 and the erase terminal 5. In the present embodiment, in contrast to the above conventional example,
The magnetic head 1 is characterized in that a PNP-type transistor 9 serving as a connecting / disconnecting device is connected between the center tap 2 of the magnetic head 1 and the power source Vcc. This transistor 9 is switched from the power source Vcc to the magnetic head 1 by an H level cutoff signal A. The supply of voltage to the center tap 2 is cut off.

In the embodiment shown in FIG. 2, P is used as the connecting / disconnecting means.
A field effect transistor (FET) 10 is used in place of the NP type transistor 9, and similarly, the supply of voltage from the power supply Vcc to the center tap 2 of the magnetic head 1 is cut off by an H level cutoff signal A. .

The cut-off signal A is generated by a detection signal of the mounted state of the floppy disk as shown in FIGS. 3A and 3B, or detects the mounted state of the floppy disk as shown in FIG. It is created by a signal and a timer that drives a spindle motor for rotating a magnetic disk.

In the example shown in FIG. 3, the detection switch 11 and the load resistor 12 are connected between the power supply Vcc and the ground GND, and the detection switch 11 detects the mounting state of the floppy disk and is at the H level when the floppy disk is not mounted and when the floppy disk is mounted. The cutoff signal A1 of L level is generated, and the detection switches 11a and 11b and the load resistors 12a and 12b of the HD magnetic disk and the ED magnetic disk are connected between the power supply Vcc and the ground GND, and the detection switch 11a,
By detecting the mounting state of the floppy disk by 11b, the interruption signal A2 of H level when not mounted and L level when mounted is generated through the AND element 13.

FIG. 5 is an explanatory diagram of the cutoff signal generation timing in the example of FIG. In FIG. 5, t1 is when a 2DD floppy disk is mounted, t2 is when a 2HD floppy disk is mounted, t3 is when a 2ED floppy disk is mounted, and cutoff signals A1 and A2 become L level when each floppy disk is mounted. It goes high when not attached.

In the example shown in FIG. 4, the cutoff signal A1 or A2 and the motor ON signal (interface signal, which is in an ON state at L level) B are input, and both signals are L.
An OR element 14 that outputs a motor-on signal (FDD internal signal, which is in an ON state at H level) C when the level is
Then, after the spindle motor starts to rotate by the motor-on signal C from the OR element 14, the period D from the timing of 0 to 500 ms to the stop of the spindle motor is H level, and the signal D is L level in other periods. A timer 15 for outputting, an output signal from the OR element 14 and an output signal D from the timer 15 are input, and a cutoff signal A3
And an AND element 16 for creating

FIG. 6 is an explanatory view of the cutoff signal generation timing in the example of FIG. In FIG. 6, t4 is the timer 1
0 ~ 500m after starting the rotation of the spindle motor by 5
It is the measurement time up to s. Then, the detection switch 11,
Alternatively, the cutoff signal A1 or A2 detected by 11a or 11b is at the L level (the mounted state of the floppy disk), and the motor-on signal B is at the L level (the on state), except at the time t4 measured by the timer 15. Is created such that the cutoff signal A3 is at the L level and the cutoff signal A3 is at the H level in other cases.

The operation of the above arrangement will be described below. When the floppy disk is mounted, since the cutoff signal A1, A2, or A3 is at the L level as described above, the PNP transistor 9 (see FIG. 1) or the FET 10 (see FIG. 2) is turned on and the power supply V
A voltage can be supplied to the magnetic head 1 from cc to operate normally. On the other hand, since the cutoff signal A1, A2, or A3 is at the H level as described above when the floppy disk is not mounted, the PNP transistor 9,
Alternatively, the FET 10 is turned off, and the supply of voltage from the power supply Vcc to the magnetic head 1 can be cut off. As a result, even if the magnetic head 1 and a portion such as the top cover grounded when the floppy disk is attached or detached, there is no electrical short circuit, and it is possible to prevent an excessive current from flowing to the magnetic head 1. it can. Therefore, it is possible to prevent failures such as burnout of the magnetic head 1 and reduction of the power supply voltage.

An analog switch can be used as the connecting / disconnecting means. In addition, the center tap 2 which incorporates the circuit of the above embodiment into the LSI and disconnects it from the LSI by the disconnecting means.
The voltage can be supplied. other than this,
The present invention can be modified in various ways without departing from the basic technical idea thereof.

[0021]

As described above, according to the present invention, the disconnecting means cuts off the power supply voltage supplied to the center tap of the magnetic head when the detecting means detects the non-mounted state of the floppy disk. Even if the magnetic head and a portion such as the top cover grounded at times come into contact with each other at the time, there is no electrical short circuit, and it is possible to prevent an excessive current from flowing through the magnetic head. Further, this makes it possible to narrow the gap between the magnetic head and the top cover and the like as compared with the related art. Therefore, the magnetic head can be protected from burning, and the overall thickness of the device can be reduced.

[Brief description of drawings]

FIG. 1 is a circuit diagram of essential parts showing a floppy disk device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of a main part showing a floppy disk device according to another embodiment of the present invention.

3A and 3B are circuit diagrams showing an example of a cutoff signal generating circuit used in the floppy disk device.

FIG. 4 is a circuit diagram showing another example of a cutoff signal generating circuit used in the floppy disk device.

FIG. 5 is a timing diagram of the cutoff signal generation in the example of FIG. 3;

FIG. 6 is a timing diagram of creating a cutoff signal in the example of FIG. 4;

FIG. 7 is a circuit diagram of a main part showing a conventional floppy disk device.

FIG. 8 is a partially cutaway side view of the floppy disk device when the floppy disk is attached / detached.

FIG. 9 is a partially cutaway side view of the floppy disk device in which a floppy disk is mounted.

[Explanation of symbols]

 1 Magnetic Head 2 Center Tap 9 PNP Type Transistor (Intermitting Means) 10 FET (Intermitting Means) 11 Detection Switch 11a Detection Switch 11b Detection Switch 15 Timer

Claims (5)

[Claims] 1. A detection means for detecting the mounting state of a floppy disk, and an interrupting means capable of cutting off the power supply voltage supplied to the center tap of the magnetic head when the floppy disk is not mounted by the detection means. A floppy disk device characterized in that 2. A detecting means for detecting the mounting state of the floppy disk, and 0 after starting the rotation of the spindle motor when the floppy disk is not mounted by the detecting means.
A floppy disk device comprising an interrupting means capable of interrupting the power supply voltage supplied to the center tap of the magnetic head except for the period from the timing of up to 500 ms to the stop of the spindle motor. 3. The floppy disk device according to claim 1, wherein a transistor is used as the interrupting means. 4. A floppy disk device according to claim 1 or 2, wherein an FET is used as the disconnecting means. 5. The floppy disk device according to claim 1, wherein an analog switch is used as the connecting / disconnecting means.