JPH076488A - Disk drive impact detecting circuit - Google Patents

Abstract

PURPOSE:To provide the impact detecting circuit of a disk drive capable of detecting an impact exerted upon the disk drive without using a special impact detecting sensor. CONSTITUTION:In a disk drive in which a head writing-in and reading-out data is moved with a stepping motor, a counter electromotive force in the coil 101 of the stepping motor is detected by providing a counter electromotive force detecting circuit 1. Further, a level detecting circuit 3 is provided in the device and an output is generated from the circuit 3 when the circuit detects that the detected counter electromotive force exceeds a constant voltage. Thus, the generation of the impact upon the disk drive is detected based on the generation of the output of the level detecting circuit 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk drive shock detection circuit for detecting a shock to a disk drive, and more particularly to detecting a shock to a disk drive without using a special shock detection sensor. The present invention relates to a shock detection circuit for a disk drive capable of

[0002]

2. Description of the Related Art Generally, a flexible disk (F
In a flexible disk drive (FDD) (hereinafter abbreviated as a disk drive) for driving D), positioning of a head for writing / reading data is performed by stepping driven by a pulse.
It is performed by open loop control by a motor (pulse motor).

In such a disk drive, it is required to detect an impact on the disk drive without using a special impact detection sensor or the like.

In this disk drive, as described above, the head is positioned by the open loop control by the stepping motor.
When an external shock is applied, the off-track may destroy the data of its own track and the data of the adjacent track.

Therefore, when an impact on the disk drive is detected, and when the impact is detected, the disk drive
It is necessary to protect the data on the drive.

Conventionally, this kind of shock detection circuit for a disk drive is provided in the disk drive for the purpose of protecting data at the time of writing, and the disk drive is equipped with a dedicated shock detection sensor. On the other hand, the impact applied from the outside is detected. As a specific example, for example, Japanese Patent Application No. 60-
As disclosed in Japanese Unexamined Patent Publication No. 228891, when a shock is detected, the writing or reading operation is stopped,
Examples include operations such as prohibiting seek operations and reporting to higher-level devices.

[0007]

In the conventional shock detecting circuit for the disk drive, since a dedicated shock detecting sensor is used, the recent compact disk drive has a large volume and a small weight. There is a problem that the ratio becomes large and becomes an obstacle to miniaturization.

Further, since such a dedicated shock detecting sensor is expensive and causes a rise in the price of the disk drive, it has sometimes been necessary to give up mounting it on the disk drive.

[0009]

It is an object of the present invention to solve the problems of the prior art as described above, and it is possible to detect an impact on a disk drive without using a special impact detection sensor. It is an object of the present invention to provide an impact detection circuit for a disk drive which is inexpensive and highly reliable as well as being able to downsize the drive.

[0010]

DISCLOSURE OF THE INVENTION A shock detecting circuit for a disk drive according to the present invention uses a stepping motor to move a head for writing and reading data. By providing a back electromotive force detection circuit that detects back electromotive force in the coil of the motor and a level detection circuit that detects that the detected back electromotive force exceeds a certain voltage, the output of this level detection circuit Detect the occurrence of a shock to the disk drive based on the occurrence.

[0011]

The counter electromotive force detection circuit 1 detects the counter electromotive force generated in the coil of the stepping motor on the basis of an external shock. The level detection circuit 2 detects that the detected back electromotive force exceeds a certain voltage and generates an output.

Therefore, by generating the output of the level detection circuit 2, it is possible to detect the occurrence of a shock to the disk drive in which the movement of the head for writing and reading data is performed by using the stepping motor. it can.

According to the present invention, when the occurrence of an impact on the disk drive is detected, the control circuit of the disk drive can stop the write operation to prevent the data from being destroyed. Further, by controlling the disc drive control circuit so as to increase the holding force of the stepping motor, it is possible to reduce reading errors and reduce power consumption. Furthermore, by generating a file unsafe output in the control circuit of the disk drive, a highly reliable disk drive can be realized.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

In FIG. 1, a driver 100 for a stepping motor drives a coil 101 of the stepping motor, and this drive loop is constructed by forming a bridge with a resistor group including the coil 101 as shown in the figure. The counter electromotive force detection circuit 1 is configured. The output of the back electromotive force detection circuit 1 is input to the amplification circuit 2 and undergoes predetermined amplification.

The output of the amplifier circuit 2 is connected to the level detection circuit 3. The level detection circuit 3 includes a first comparator 31 that detects that the output level of the amplifier circuit 2 is higher than a predetermined value, and a second comparator 32 that detects that the output level of the amplifier circuit 2 is lower than a predetermined value. An OR circuit 33 that obtains the logical sum of the detection signals of the comparators 31 and 32, and outputs the shock detection signal 30 when the input voltage exceeds a certain level in either the positive or negative direction.

When the disk drive is going to perform a write operation, the head is advanced by switching the excitation phase of the stepping motor to the target cylinder, and the excitation current is fixed when the target position is reached. , The write operation is performed after the vibration is converged after waiting for a certain period of time.

Since the exciting current of the stepping motor is fixed during the writing and reading operations,
The AC component of the output of the back electromotive force detection circuit 1 is 0 [V]. However, when the stepping motor receives a driving force in the operation direction from an external impact in the direction in which the off-track occurs, a counter electromotive force is generated in the coil 101.

In the present invention, by amplifying this counter electromotive force, setting an appropriate reference level, and detecting it,
Detects vibration and shock from the outside. In the embodiment of FIG. 1, the level amplifier circuit 2 has a differential input because the single output voltage of the counter electromotive force detection circuit 1 is at a level close to the power supply voltage and the fluctuation of the power supply voltage is the counter electromotive force. This is to prevent erroneous detection when it is larger than

FIG. 2 shows a second embodiment of the present invention. In FIG. 2, the coil 102 of the stepping motor has a center tap. In this case, as shown in the embodiment of FIG. 1, a back electromotive force detection circuit may be configured using a bridge, but the driver circuit 100 has an output circuit configuration as shown in FIG. Because
As the center tap voltage, approximately half the power supply voltage is output.

Therefore, the counter electromotive force can be taken out by one output line from the center tap of the coil 102 by providing half of the power supply voltage as the reference voltage of the amplifier circuit 2. That is, in this case, the coil 102 also serves as the counter electromotive force detection circuit.

FIG. 3 shows a configuration example of the write stop circuit. D-type flip-flop (DFF)
When the shock detection signal 30 is input during the write operation, the latch 40 latches the shock detection signal 30 to stop the write control signal and holds this state.

When the write signal is input again, the DFF
Since the latch of 40 is held in the released state, the write control signal becomes the write state via the OR circuit 41.

[0024]

As described above, according to the present invention,
It is possible to configure the shock detection circuit of the disk drive without using a special shock detection sensor, and as a result, it is possible to surely eliminate the obstacles in the miniaturization of the disk drive. As a result, it is possible to provide an unprecedented excellent shock detection circuit for a disk drive, which can significantly improve the reliability of the disk drive.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a specific example when the present invention is incorporated in a write stop circuit.

[Explanation of symbols]

 1 Back electromotive force detection circuit 3 Level detection circuit 101, 102 Motor coil

Claims (3)

[Claims] 1. A disk drive in which a head for writing and reading data using a stepping motor is moved to detect a back electromotive force in a motor coil of the stepping motor. A circuit and a level detection circuit for detecting when the back electromotive force exceeds a certain voltage, and detecting the occurrence of a shock to the disk drive based on the output of the level detection circuit. Characteristic disk drive shock detection circuit. 2. The counter electromotive force detection circuit is configured by a bridge circuit in which a motor coil of a stepping motor is one side and the other three sides are electric resistors, and a balance point thereof is an output terminal. The shock detection circuit for a disk drive according to claim 1. 3. The back electromotive force detection circuit is constituted by a midpoint provided in a motor coil of a stepping motor, and is used as an output terminal of the back electromotive force detection circuit. Shock detection circuit for disk drives.