JPS63205852A - Detection circuit for spindle rotation abnormality - Google Patents

Abstract

PURPOSE:To prevent an erroneous action in the rotation control of a spindle due to noise by measuring the interval of an output pulse in a rotation detection element at every other cycle and transmitting an alarm only when the abnormality of twice-rotation is successively detected. CONSTITUTION:An inversion means 18 inverts an output by the pulse of a terminal A and alternately transmits '1' and '0' to a counting means 20 and a pulse extraction means 19. If the output of the means 18 is '1', the means 20 starts counting and a first terminal transmits '1' to a decision means 21 at a prescribed value, and a second terminal also transmits '1' after the prescribed value. On the other hand, the means 19 transmits the pulse of the terminals A to the means 20 and the means 21. The count value of the means 20 is reset by the output pulse of the means 19. The means 21 decides abnormality when the first terminal in the means 20 is '0' or the second terminal is '1', and when it receives the pulse from the means 19. If the abnormality decision continues twice, the alarm is transmitted and the erroneous action in the rotary control of the spindle due to noise is prevented.

Description

[Detailed Description of the Invention] [Summary] When detecting abnormal rotation of a spindle using pulses sent out by a rotation detection element incorporated in a DC motor,
When noise is added to the output of the rotation detection element, the time interval between pulses is measured every other period by utilizing the discontinuity of the noise to avoid sending out false alarms due to abnormal rotation of the spindle. , an alarm will be sent if a rotation abnormality is detected twice in a row.

[Industrial application field]

The present invention relates to a spindle rotation abnormality detection circuit for detecting an abnormal rotation speed of a spindle used in, for example, a magnetic disk drive.

Magnetic disk drives are used as one of the auxiliary storage devices in computer systems, but as storage capacity increases, various alarms are issued to quickly detect device abnormalities and protect recorded data. Functions are being added.

Incidentally, a magnetic disk device uses a spindle that holds a disk and rotates at high speed and with high precision, and is driven by a motor. If the rotational speed of this spindle becomes faster or slower than the standard, normal seek operation (head positioning works) and data read/write operations will not be possible. Equipped with a rotation speed abnormality detection circuit.

This rotational speed abnormality detection circuit detects when the rotational speed of the spindle is
Generally, when the range of ±2 to 5% of the target rotational speed is exceeded, the supply of drive current to the motor is immediately stopped, and the host device is notified of the spindle rotational abnormality to report the inoperability.

Therefore, it is necessary to prevent the rotation speed abnormality detection circuit from malfunctioning. - [Prior Art] FIG. 4 is a block diagram illustrating a conventional technology.

Generally, the spindle of a magnetic disk drive is a DC motor 1.
A rotational speed detection element 2 such as a Hall element built into the DC motor 1 sends pulses indicating a period corresponding to the rotational speed to the DC motor control circuit 4.
and is sent to the rotation speed abnormality detection circuit 5.

The DC motor control circuit 4 sends a control signal to the DC motor drive circuit 3 according to the period of this pulse, and when the rotation speed of the DC motor 1 decreases, the DC motor control circuit 4 controls the rotation speed of the DC motor 1 to increase, and the rotation speed increases. Then, the rotational speed of the DC motor 1 is controlled to decrease, and the rotation of the spindle is controlled to be maintained at the target rotational speed.

The rotational speed abnormality detection circuit 5 uses a clock to count the period of the pulse sent out by the rotational speed detection element 2, and detects whether the rotational speed of the DC motor 1 is within an allowable range with respect to the target rotational speed. When the target rotational speed exceeds the allowable range, a spindle speed alarm is sent to terminal B, and a signal is sent to the DC motor control circuit 4 to stop the current supplied to the DC motor l.

FIG. 5 is a detailed block diagram of the rotational speed abnormality detection circuit 5 shown in FIG.

The counter 6 performs a counting operation using the clock sent out by the reference signal oscillation circuit 11, and when it reaches a predetermined count value, the FAST
"1" is sent from the terminal, and when a certain value is counted beyond this predetermined count value, "1" is sent from the LATE terminal. On the other hand, a pulse sent out by the figure rotation speed detection element 2 is input from the terminal A, and the counter 6 is reset.

By the way, when a pulse is input from terminal A after the FAST terminal has sent out "1", the NOT circuit 7 is sending out "0", so the AND circuit 8 is still sending out "0". , when a pulse is input from the terminal A while the FAST terminal is sending out "0", the AND circuit 8 sends this pulse to the terminal B via the OR circuit 10. In this case, the reason is that the rotation speed of the DC motor 1 is too fast, and the pulse sent from the terminal B is used as a signal for the spindle speed alarm.

Also, while the LATE terminal is sending out “0”, the terminal A
When more pulses are input, the AND circuit 9 continues to send out "O", but when a pulse is input from the terminal A after the LATE terminal has sent out "1", the AND circuit 9 sends this pulse to the OR circuit 10. The signal is sent to terminal B via . In this case, it is because the rotational speed of the DC motor 1 is too slow.
The pulse sent from terminal B is used as a spindle speed alarm signal.

[Problem that the invention seeks to solve]

FIG. 6 is a time chart explaining the operation of FIG. 5.

Figure 6(a) shows the period T of each pulse input from terminal A.
+, T L T : l, T 4 indicates a normal case, and each pulse has a period such that it is input while the FAST terminal of the counter 6 is sending out "1" and the LATE terminal is sending out 0'. Therefore, "0" is still being sent to terminal B.

Figure 6 fb) shows the case where noise ■ is mixed into terminal A. The periods T, , T, , T of each pulse are normal, but because of the noise mixed in, the intervals T s and T 6 are The cycle is short. Therefore, the FAST terminal of counter 6 is “0”.
”, and when the noise ■ is input to terminal A, a spindle speed alarm will be sent from terminal B.

Conventionally, when noise enters terminal A, an alarm is sent out even if the spindle speed is normal, but the rotational speed detection element 2 shown in FIG. There is a strong current flowing through the DC motor 1 and a strong magnetic field generated by the DC motor 1, and this signal line is prone to noise, which causes a false detection of an abnormal rotation speed of the spindle and sends out a spindle speed alarm. There is a problem with doing so.

Measures to solve problem C] FIG. 1 is a block diagram of the principle of the present invention.

23 is a determining means, and a reversing means 18, which will be explained below,
It has a pulse extracting means 19, a counting means 20, and a determining means 21.

The inverting means 18 inverts its output in response to a pulse input from the terminal A, and sends "1" and "O" alternately to the counting means 20 and the pulse extracting means 19.

The pulse extracting means 19 sends out the pulse input from the terminal A to the counting means 20 and the determining means 21 when the inverting means 18 sends out "1".

The counting means 20 is enabled and starts counting when the inverting means 18 sends out "1", and when a predetermined count value is counted, it sends "1" from the first terminal to the determining means 21, When a certain value is further counted beyond the count value of , "1" is sent to the determination means 21 from the second terminal. Further, it is reset by the pulse sent out by the pulse extracting means 19, and becomes disabled when the inverting means 18 sends out "0".

The determining means 21 determines whether the first terminal of the counting means 20 is sending out "O" or the second terminal is sending out "1", and if the pulse extracting means 19 sends out a pulse, ,
It is determined that there is an abnormal rotation of the spindle, and the counting means 2
If the pulse extraction means 19 sends out a pulse when the first terminal of 0 is sending out "1" and the second terminal is sending out "0", it is determined that the rotation of the spindle is normal. do.

The continuous abnormality detection means 22 stores this determination when the determination means 21 determines that the rotation is abnormal, and erases this memory when the determination means 21 determines that the rotation is normal. 21 determines that the rotation is abnormal, it sends a spindle speed alarm to terminal B.

[Effect]

With the above configuration, the inverting means 18 outputs an output that is inverted every time a pulse is input, causes the counting means 20 to count the period of every other pulse, and causes the determining means 21 to determine whether the period of the pulse is normal or not. is determined, and when this determination is abnormal, this abnormality determination is stored in the continuous abnormality detection means 22.

Then, when the pulse period is normal, the pulse extracting means 19 causes the determining means 21 to send out a signal for erasing the abnormality judgment stored in the continuous abnormality detecting means 22.
It becomes possible to send out a spindle speed alarm only when the number 1 is determined to be abnormal continuously, and it is possible to prevent sending out false alarms due to discontinuous noise.

〔Example〕

FIG. 2 is a block diagram of a circuit showing an embodiment of the present invention.
FIG. 3 is a time chart explaining the operation of FIG. 2.

The flip-flop 12 inverts the output of the Q terminal every time a pulse is input from the terminal A, and enables the counter 6 when it sends out "1", and enables the counter 6 when it sends out "0".
is disabled.

Since the AND circuit 13 sends out a manually input pulse from the terminal A when the flip-flop 12 sends out 1'', every other pulse input from the terminal A is sent to the AND circuit 15 in synchronization with the operation of the flip-flop 12. and is sent to the reset terminal of counter 6.

For this reason, the counter 6 uses the clock sent out by the reference signal oscillation circuit 11, and the periods T1 and T3 shown in FIG.
Alternatively, the cycles T2 and T4 are counted, and as explained in Fig. 5, when a predetermined count value is reached, 1'' is sent from the FAST terminal, and when a constant value is counted beyond this predetermined count value, LATE is sent. Send “1” from the terminal.

Here, after the FAST terminal sends “1”, AND
When the circuit 13 sends out a pulse, the NOT circuit 7 becomes “0”.
, the AND circuit 8 continues to send O''. Also, at this time, the LATE terminal of the counter 6 is “
Since it is sending out a 0'', the NOT circuit 14 is sending out a 1. Therefore, the AND circuit 15 sends out "1" while the pulse is being input. And AND circuits 8 and 9
does not send out this pulse, and the pulse sent out by AND circuit 15 resets flip-flop 16.

Therefore, the Q terminal of flip-flop 16 is 01,
Since the output of the OR circuit 10 is also "0", the AND circuit 17 continues to send out "0".

As shown in FIG. 3(b), if noise is input and the counter 6 counts this cycle T, the AND circuit 13 sends out a pulse while the FAST terminal is sending out "O". . Therefore, the AND circuit 8 sends this pulse to the S terminal of the flip-flop 16 and the AND circuit 17 via the OR circuit 10. Since the AND circuit 15 does not send this pulse to the R terminal of the flip-flop 16, the flip-flop 16 is set when the clock is input and stores that an abnormality has occurred. And the Q terminal is “1”
However, since the pulse sent by the OR circuit 10 has disappeared at this time, the AND circuit 17 continues to send "O" to the terminal B.

In this case, since the flip-flop 12 is inverted, the counter 6 does not count the period Th, but counts the next period T3, but since there is no noise on the period T, it is normal, and the AND circuit 15 sends a pulse to the R terminal of the flip-flop 16 to reset the flip-flop 16 and erase the memory of the occurrence of the abnormality.

FIG. 3 (As shown in C1, the cycle T due to the occurrence of a failure.

From period T,. Assuming that the period between T? When the flip-flop 16 is sent and the Q terminal is sending out "1", the counter 6
The period T counted by is also short, and the FAST terminal is “0”.
'', the AND circuit 8 sends out a pulse, so the AND circuit 17 sends this pulse to terminal B,
Spindle speed alarm.

While the LATE terminal of counter 6 is sending out O'',
When the AND circuit 13 sends out a pulse, the AND circuit 9 continues sending out "0", and the pulse is N.

The T circuit 14 sends "1" to the AND circuit 15.

At this time, the FAST terminal is sending out “1”, so the AN
The D circuit 15 sends the pulse sent out by the AND circuit 13 to the R terminal of the flip-flop 16.
Reset 6.

Also, after the LATE terminal sends “1”, AND circuit 1
3 sends out a pulse, the AND circuit 9 sends this pulse to the S terminal of the flip-flop 16 and the AND circuit 17 via the OR circuit 10.

Therefore, in the same manner as described above, the flip-flop 16 stores the occurrence of an abnormality, and the next period counted by the counter 6 is also held at the terminal L.
When the AND circuit 13 sends out a pulse after ATE sends out "l", a spindle speed alarm is sent out from terminal B.

In this embodiment, since the pulse input from terminal A occurs once per rotation of the disk, an alarm will be issued after a maximum of 4 rotations after the occurrence of abnormal rotation of the spindle. However, in general, the rotational inertia of the disk is enormous. Since the experimentally confirmed rotational speed fluctuation due to a failure is about 0.2%/rotation, this degree of delay is out of the question.

〔Effect of the invention〕

As described above, the present invention can prevent malfunctions due to noise in the circuit for detecting abnormal rotation of the spindle, and can accurately detect abnormal rotation due to the occurrence of a failure.

[Brief explanation of the drawing]

Fig. 1 is a principle block diagram of the present invention, Fig. 2 is a block diagram of a circuit showing an embodiment of the present invention, Fig. 3 is a time chart explaining the operation of Fig. 2, and Fig. 4 is a block diagram of the principle of the present invention.
5 is a detailed block diagram of the rotational speed abnormality detection circuit of FIG. 4, and FIG. 6 is a time chart explaining the operation of FIG. 5. In the figure, 1 is a DC motor, 2 is a rotational speed detection element, 3 is a DC motor drive circuit, 4 is a DC motor control circuit, 5 is a rotational speed abnormality detection circuit, 6 is a counter, 7.14 is an N07 circuit, 8. 9.
13.15.17 is an AND circuit, 10 is an OR circuit,
11 is a reference signal generating circuit, 12 and 16 are flip-flops, 18 is an inverting means, 19 is a pulse extracting means, 20 is a counting means, 21 is a determining means, and 22 is a continuous abnormality detecting means.

Claims (2)

[Claims] (1) The time between pulses from a rotation detection element that detects the rotation of a spindle rotating at a predetermined speed is measured every other cycle, and if the measurement result is outside a predetermined range with respect to a predetermined reference value, means (23) for determining rotational abnormality; and continuous abnormality detection means (23) for outputting a rotational abnormality signal when the determining means (23) detects rotational abnormality several times in succession.
2) A spindle rotation abnormality detection circuit comprising: (2) The determining means (23) includes an inverting means (18) that sends out an output that is inverted every time the pulse sent out by the rotation detection element is input; and when the inverting means (18) sends out "1"; When the pulse extracting means (19) that sends out the pulse and the inverting means (18) send out "1", it becomes enabled and starts counting, and when a predetermined count value is counted, it becomes "1".
The pulse extraction means (19) has a first terminal that outputs "1" and a second terminal that outputs "1" when a certain value is counted beyond the predetermined count value. When it is reset and the inverting means (18) sends out "0",
a counting means (20) which is disabled, and when the first terminal of the counting means (20) is sending out "0" or the second terminal is sending out "1", the pulse If the extraction means (19) sends out a pulse, it is determined that there is an abnormal rotation of the spindle, and the counting means (2)
The first terminal of 0) sends “1” and the second terminal sends “0”
is configured to determine that the rotation of the spindle is normal if the pulse extraction means (19) sends out a pulse while the pulse extraction means (19) is sending out a pulse, and the continuous abnormality detection means (22) detects the determination means (21). ) is configured to memorize this determination when the determination means (21) determines that the rotation is abnormal, and to erase this memory when the determination means (21) determines that the rotation is normal; The spindle rotation abnormality detection circuit according to claim 1, wherein when the rotation abnormality is determined, a signal notifying the rotational speed abnormality of the spindle is sent out.