JPS58218084A - Emergency head retractor of magnetic disc driving mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates generally to magnetic disk memories of the type that utilize floating transducer heads, and more specifically, to magnetic disk memories of the type that utilize floating transducer heads. The present invention relates to a device for moving an object to a landing zone.

(2) Background of the Invention In high-performance magnetic disk memories, read/write heads are kept from touching the respective disk surfaces;
The air flow induced by the rapidly rotating disk is actually sufficient to support the head which is blown very little distance from the disk surface. However, as the speed of the disk decreases, for example as a result of loss of power to the spindle motor, the air flow created by the disk stagnates until a point is reached where support for the floating head ceases. A resulting head crash 1 on the portion of the disk surface dedicated to data storage can cause damage to both the head and disk surface, as well as loss of data.

Accordingly, various devices have been devised to prevent contact between the head and the disk surface in the event of loss of power to the spindle motor. In general.

These devices detect a power failure condition and either lift each head off its respective disk surface and hold it away, or each head can be safely brought into contact with a decelerating disk. It is equipped with a backup energy supply for the machinery or electrical equipment used to move each bed to the head removal location. As a backup energy source to remove (or lift) the head in case of power failure.

An example of a mechanical device using springs is U.S. Patent No. 5.702.
,997, while U.S. Pat.
No. 257,501 exemplifies an electrical system in which emergency energy stored in a capacitor kept fully charged during normal operation is used to energize the head positioning motor. , moving the head in a controlled manner to the head removal location.

Prior art emergency head removal or retraction devices are bulky and expensive, in part due to the fact that they require a relatively large number of mechanical, electromechanical or electrical components, some of which tend to be expensive. Price is a feature.

For example, for adequate reserve energy storage, emergency removal or retraction capacitors must be relatively large, thus requiring more cost and space.

Together these factors add up to 15.5'+ crn (5
n inch):)□ 91' too:) &/J゛, y>f4 □kf@r6'1
As the demand for V-9 disk drives and mechanisms continues to expand11, they are becoming extremely important.

SUMMARY OF THE INVENTION In accordance with a general aspect of the invention, detecting a power failure condition that reduces or may reduce the speed of the spindle motor causes the windings of the spindle motor to connect to the head positioning motor. The electromotive force generated by the rotating spindle motor is used to power the head positioning motor to quickly move or retract the floating head to the landing zone, where it can be brought into safe contact with the respective disk surfaces. As used in the description and claims, a "power failure" need not result in a complete loss of power, but rather a power failure in either the power supply energizing the spindle motor or the power supply powering the spindle motor command circuit. A relatively small drop in voltage level is sufficient, according to one embodiment of the present invention, to initiate an emergency head retraction f:. In any event, only a relatively small number of small, inexpensive components are required to implement the inventive concept.

(++l DETAILED DESCRIPTION The invention will be better understood when the following detailed description is read in conjunction with the accompanying drawings.

FIG. 1 shows a magnetic disk drive 10.1 that includes at least one disk 12 mounted on a spindle. A movable head support mechanism 18f for radially positioning an electromagnetic transducer head 16 for writing to and reading from both magnetic surfaces of the disk 12 and a read/write head relative to a series of concentric data tracks on the disk surface. It shows. Radial movement of the support mechanism 1g is limited by an inner stop 20 and an outer stop 22 that project from a base plate 211 forming part of the housing of the disk drive mechanism. Supported by a support mechanism 18.

A post 26 having a resilient outer surface is constructed to engage the inner stop 20 and the outer stop 22.

According to the particular embodiment contemplated, a landing track or zone is provided on each didek surface adjacent to the innermost data track, and when the post 26 rests against the inner stop 20, each head is provided with a respective landing zone. is positioned directly above the Alternatively, the first side band may be placed outside the outermost data track.

In this case each head is in its respective landing position when the post 26 engages the outer stop 22.

The disk 12 is rotated at a constant speed around an axis 28 by a DC motor 30 connected to a spindle 111.
Meanwhile, the head support mechanism 18 is moved toward and away from the axis @28 by a bidirectional DC head positioning motor 32. Positioning of each head can be accomplished in a variety of ways known in the art, such as, for example, by closed loop servo systems.

The spindle motor 30 is energized by a spindle motor drive circuit IIO connected to the permanent magnet rotor shell 4 and a common ground point and controlling the power to the motor from a voltage supply of 10 V2 (usually 12 volts). It consists of a pair of coiled stator windings 6 and 58. circuit 'I
O = Accurately control the rotational speed of the disc and perform the technique
It may be comprised of any of a variety of speed regulating circuits known in the art. According to the preferred embodiment, suitably timed drive pulses, shown schematically as 636 and ``38'' in FIG. 2, receive logic signals controlled by a microprocessor applied to input terminal 42.

applied to windings 36 and 58. As is well known, microprocessors and associated logic elements (not shown) are typically powered by a +5v power supply, generally referred to herein as +V.

The head positioning motor 2, which may be of the ordinary voice coil type, is energized by a power supply voltage 12 and has terminals connected across a conventional bridge-type power amplifier circuit 511 comprising 11 power transistors 55-58. 50 and 52
have. Series RC connected to both ends of motor 32
Circuit 60 shunts high voltage spikes that appear at the motor terminals during starting.

The power amplifier transistors 55 and 56 are controlled by a first transistor amplifier 62, and the first transistor amplifier 62 is turned on. +■2 From the power supply, go through the transistor 56° motor U2 and the transistor 55, and then from there to the ground point 64
A current path is formed that leads to . Thereby the motor 52
Each read/write head 1 is activated by a positive voltage applied to terminal 50 of
6 inward, ie.

Driven towards axis 28. Similarly, the conduction of power transistors 57 and 58 is controlled by a second transistor amplifier 66 to direct each head outwardly, i.e.
Power y+v2 so as to move away from the axis 28
from the power source to the other terminal 52 of motor 2. Transistors 62 and 66 are in turn controlled by a suitable position motor direction and speed command circuit 68 whose outputs are connected to the bases of these transistors.

Circuit 68 is conventional and responsive to an analog input signal;
Which bridge transistor pair (55156 or 57
75 B) determines whether conduction occurs and the magnitude of the conduction.

As previously mentioned, in the exemplary embodiment being considered, the landing track for each head 16 is located radially inboard of the data tracks of disk 12. Therefore, during a normal power down sequence, transistor 5
5 and 56 are biased into conduction, thereby causing the head support mechanism post 26 to become inwardly stopped 20.
The motor 52 is energized in a direction to drive the welding process, and the spindle motor 52 is subsequently de-energized to eventually bring each head onto the surface. To facilitate the description of the invention, the movement of each head relative to its respective landing zone, whether those zones are located outside or inside the data track, is generally referred to as head 1 retraction 1. I'll decide.

Reference numeral 70 indicates an emergency head retraction circuit that is activated when the voltage on one or both of the 10V or +v2 supplies falls below a predetermined level. These voltage drops are detected by a voltage monitoring circuit 72 shown in FIG. 5 and described below, resulting in its output vR
is normally pulled from a few positive volts to near ground potential. 8 is applied to the non-inverting input terminal 711 of the comparator 76, and the reference terminal 78 of the comparator 76 is connected to a voltage divider network consisting of a diode 80 (to which 10V2 is applied), a resistor g2, and a diode pair 811. Approximately +1. lI
It is maintained at V. Resistor 85 connects to terminal 7111F: ground. When VR falls below the reference level set at terminal 78, the voltage at output 86 of comparator 76 switches to ground potential. The output 86 is connected to the base of a P N P'' power transistor 88, which is normally biased to the off state when the comparator output 86 is high.
The emitter terminal of 8 is connected to the power supply via diode 80.
2 and normally reverse biased diodes 90 and 92! Rat and spindle
It is connected to the stator winding of the motor 22. The collector of transistor 88 is connected to terminal 50 of the single positioning motor through diode 91i'i and to the base of bridge power amplifier transistor 55 through a series combination of diode 96 and resistor 98. .

When ■8 falls below the reference voltage at terminal 78 of comparator 76 to +V, or signals that either ■2 has fallen below a predetermined level, the resulting As for the descent.

It will be seen that driving the base of transistor 88 turns that transistor on. In the event of a partial or complete loss of power supply +v2, power to the comparator circuit is generated by spindle motor 22, which is slowing down. The waveform of the emf induced in the spindle motor windings 36 and 58 will be similar to that shown, somewhat idealized, in FIG. So volume 1? The voltage output e36 of R36 is.

A series of alternating positive and negative pulses approximately symmetrical about ground potential, with a similar series of pulses produced by winding 3g (e and 18♂ out of phase).

Negative currents from both windings are blocked by diodes 90 and 92, and a nearly constant level of positive voltage is applied to terminal 50 of head positioning mode controller 2 and the base of bridge power amplifier transistor 55. and bias the transistor into conduction. A complete circuit is thus established via transistor power amplifiers 55 and 88 in communication between the spindle motor windings 6,5g and the head positioning motor windings 2. As a result of this emergency drive circuit being completed, the head positioning motor 2 is driven by the housing in which the post 26 engages the inner stop 20 in a direction that moves each head inwardly, i.e. towards the axis 28 of the spindle. be done.

Referring now to FIG. 11I1. It includes a series combination of a resistor 110 and a Zener diode 112 connected between +v2 and ground to create a reference voltage applied to the inverting terminals of l16 and l18. The outputs of comparators 11II and l16 are
Both are connected to the non-inverting input terminal 1'20 of the fifth comparator 11g. Resistor 122 connects input 120'1ji7+
V2 power supply, while a small capacitor 1211 is connected between terminal 1'20 and ground. Resistor 12
The voltage across resistor 126, which forms part of a voltage divider consisting of 6 and 128 and monitors the voltage +V+', is applied to the input terminals of comparators 1 and 16. Similarly, resistor 1
The resistor j 50 of the second voltage divider, consisting of 0 and 152, produces a voltage proportional to the voltage applied to the input of the comparator 1'll. When the input voltage to either comparator 1111 or 116 falls below the nine reference voltage set by Zener diode 112, comparator 11
It will be seen that the normally high level voltage appearing at input 1'20 of 8 is pulled near ground potential, thereby lowering 2 to approximately the daughter ground as well.

[Brief explanation of the drawing]

1 is a diagram illustrating a somewhat simplified magnetic disk memory drive and a portion of a circuit incorporating an exemplary embodiment of the present invention; FIG. FIG. 5 is a circuit diagram of the power supply voltage monitoring circuit. 10--Magnetic disk drive mechanism, 12--Magnetic disk. 1II--spindle, 16--electromagnetic transducer head, 5
0-- spindle motor, qo-- spindle motor drive circuit, 511-- power amplifier circuit, 68-- head positioning motor direction and speed command circuit, 70--
Emergency head retraction circuit. FIG, 2 FIG, 3

Claims (1)

Claims: 1. At least one rotatable disk having a surface containing a magnetizable data storage portion. a motor that rotates the disk; at least one electromagnetic transducer head for transferring data to and from the magnetizable data storage portion on the disk; and head movement means for moving the head relative to the surface of the disk. and a power supply means for supplying power to the components. means for connecting a motor to the head moving means in response to a power abnormality condition, the electromotive force generated by the motor providing power to drive the head away from the data storage section of the disk and into the landing zone; A magnetic disk memory device characterized by: 2. Voltage comparing means for connecting the motor to the head moving means to compare the voltage level of the power supply means with a reference voltage and outputting an output signal indicating an abnormal state of the power supply; and an output provided by the voltage comparing means. 2. The magnetic disk memory device according to claim 1, further comprising switching means for switching the motor to be connected to the head moving mechanism upon receiving a signal.