JPH02179285A - Controller of spindle motor - Google Patents

Abstract

PURPOSE:To prevent the rotation of a spindle motor from varying by detecting the defect of an encoder pulse signal, forming a complementary pulse for complementing it, and combining it therewith. CONSTITUTION:A controller of a spindle motor SM is composed of a control unit 20, a reference signal generator 2, an incremental/decremental counter 23, a D/a converter 26, a motor driver 29, etc. The control unit 20 determines whether an encoder pulse signal SE is defective or not on the basis of the time interval of the change of the signal SE, and outputs a complementary pulse signal SC at the time of defect. As a result, the encoder pulse signal SE is corrected on the basis of the complementary pulse signal SC.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a control device for a spindle motor that rotationally drives a disk storage medium.

[Prior art] For example, a spindle motor S that rotationally drives an optical disk
An example of H is shown in FIG.

This spindle motor SMj±, optical disk (path shown)
a shaft 2 having a turntable l attached to its tip for attaching it; a lower yoke 3 attached to the lower end of the shaft 2; a permanent magnet 4 disposed on the lower yoke 3;
It consists of a drive coil 5 disposed to face the permanent magnet 4 and an upper yoke 6 to which the drive coil 5 is attached.Furthermore, below the lower yoke 3 is an encoder plate 7 constituting a rotary pulse encoder PH. is arranged, and
An optical sensor 9 for detecting the pattern 8 on the encoder plate 7 is provided.

Further, a cover 1O is provided to cover the main body of the spindle motor SH to prevent dirt and dust from adhering to the optical paths of the encoder plate 7 and the optical sensor 9.

With the above configuration, when a drive signal is applied to the drive coil 5 from a drive circuit (not shown), the lower yoke 3 rotates, and the shaft 2 and turntable 1 rotate accordingly.

At the same time, every time the shaft 2 rotates by a predetermined angle, the pulse encoder PE outputs an encoder pulse signal P with a duty of 50%, as shown in FIG. 2(b).
1 is output.

On the other hand, a control section f that controls the rotation of the spindle motor SH
i! (not shown) generates a reference pulse signal P2 of a frequency corresponding to the reference rotation speed of the spindle motor SH,
A control signal is given to the drive device so that the phase difference Δt between this reference pulse signal P2 and the encoder pulse signal pt output from the pulse encoder PR is equal to or less than a certain value.

In this way, the rotation of the spindle motor SH is controlled based on the encoder pulse signal PI output from the pulse encoder PE.

[Problems to be Solved by the Invention] However, such conventional devices have the following disadvantages.

That is, for example, if dirt or dust adheres to the pattern 8 portion of the encoder plate 7 of the pulse encoder PH, the encoder pulse signal PI will be lost as shown in FIGS. 11(a) and 11(b).

In this way, when the encoder pulse signal P1 is missing, the phase difference Δtj, Δt'' between the reference pulse signal P2 and the encoder pulse signal P1 becomes very large, so the control device adjusts the phase difference Δt', Δt. ``'' acts in a direction that coincides with the reference phase difference Δt, resulting in an inconvenience that rotational fluctuations of the spindle motor SM become large.

Therefore, in order to solve this problem, a cover 10 is installed to prevent dirt and dust from entering from the outside, but if there is dirt attached to the drive coil 5, etc., the dirt may It may fall and adhere to the encoder plate 7.

For this reason, it is necessary to thoroughly clean the drive coil 5 and the like, resulting in an inconvenience that the cost at the time of assembly increases.

SUMMARY OF THE INVENTION An object of the present invention is to provide a spindle motor control device that can solve the problems of the conventional devices and prevent rotational fluctuations of the spindle motor.

[Means for Solving the Problems] The present invention provides a pulse signal loss detection means for detecting loss of an encoder pulse signal based on a signal change time interval of the encoder pulse signal, and a supplementary pulse signal loss detection means when the pulse signal loss detection means performs a detection operation. The encoder includes complementary pulse signal generating means for generating a pulse signal, and pulse signal synthesizing means for generating a corrected encoder pulse signal by combining the complementary pulse signal and the encoder pulse signal.

[Operation] Therefore, when an encoder pulse signal is missing, a complementary pulse signal that interpolates the missing encoder pulse signal is output, and the encoder pulse signal is corrected based on this complementary pulse signal, so that the spindle motor Rotational fluctuations are prevented.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a spindle motor control device according to an embodiment of the present invention. Note that this device is applied to a spindle motor having the same configuration as shown in FIG.

In the figure, the duty output from the pulse encoder PE as the spindle motor SH rotates is 50%.
The encoder pulse signal SE is applied to one input terminal of the control section 20 and the exclusive OR circuit 21.

The reference signal generation circuit 22 outputs a signal from the pulse encoder PE when the rotation of the spindle motor SH reaches the target speed.
The reference pulse signal PR has the same waveform as the encoder pulse signal SE output from the encoder pulse signal SE (see FIGS. 2(a) and (b)). A count input U, a control unit 20 and a frequency/voltage converter 24 are added. Further, the frequency of the reference pulse signal PR generated by the reference signal generation circuit 22 is controlled by the control section 20.

The control unit 20 controls the spindle motor SM to a target rotation speed, and when the rotation speed of the spindle motor SH corresponding to the target speed reaches the target value, the time interval of the signal change of the encoder pulse signal SE is changed. Based on this, it is determined whether or not the encoder pulse signal SE is missing. If it is determined that the encoder pulse signal SE is missing, a complementary pulse signal SC is outputted to the other input terminal of the exclusive OR circuit 21.

The output signal of the exclusive OR circuit 21 is sent to the down count input terminal D of the up/down counter 23 and the frequency/voltage converter 25 as a correction encoder pulse signal PE.
has been added to.

The up/down counter 23 is for detecting the phase difference between the reference pulse signal PR and the corrected encoder pulse signal PE, and is up/down in synchronization with the rising edge of the reference pulse signal PR applied to the up count input terminal υ. Along with the counting operation, the down-counting operation is performed in synchronization with the rising edge of the correction encoder pulse signal PE applied to the down-counting input edge, and the counting result is sent to the control unit 20 and the control unit 20 as phase error data DE (signed). is added to the digital/analog converter 26.

The frequency/voltage converter 24 forms a speed reference signal SR of a voltage corresponding to the frequency of the reference pulse signal PR, and the speed reference signal SR is applied to the + side input terminal of the deviation calculator 27. There is.

The frequency l voltage converter 25 forms a speed detection signal sp of a voltage corresponding to the frequency of the corrected encoder pulse signal PE, and the speed detection signal sp is applied to one input terminal of the deviation calculator 27. ing.

The deviation calculator 27 calculates the speed reference signal SR and the speed detection signal s.
The calculation result is added to the adder 28 as a speed error signal SS.

The digital/analog converter 26 outputs phase error data DE
is converted into a corresponding analog signal, and the analog signal is outputted to the adder 28 as a phase error signal SR. Note that the phase error signal S8 is the phase error data DE
It has a polarity corresponding to the sign of .

Adder 28 adds speed error signal SS and phase error signal SB, and outputs the addition result signal to motor drive circuit 29 as error signal CC.

The motor drive circuit 29 changes the drive signal C applied to the spindle motor SH in the direction in which the error signal CC becomes 0.
Change D.

FIG. 3 shows an example of processing executed by the control unit 20 when controlling the rotation of the spindle motor SH.

First, the rotational speed of the spindle motor SH is set, and the frequency setting signal DT corresponding to the rotational speed is output to the reference signal generation circuit 22. At the same time, the reference pulse signal PR output from the reference signal generation circuit 22 at that time is The pulse width 172 is set to time Δtr, and the pulse width of the reference pulse signal PR is set to time Δt2 (processing 101).

Thereby, the reference pulse signal PR output from the reference signal generation circuit 22 becomes a pulse signal with a frequency corresponding to the target rotational speed of the spindle motor SH.

On the other hand, at that point, the rotational speed of the spindle motor SH is largely deviated from the target rotational speed, so 1. For example,
When the rotational speed of the spindle motor SM is smaller than the target speed, the count value of the up/down counter 23 overflows in the positive direction, thereby changing the phase error signal SB to the maximum positive value.

In this state, the control unit 20 does not output the complementary pulse signal Sε, and the signal level at the other input terminal of the exclusive OR circuit 21 is fixed at the logic L level, so the encoder pulse signal SE is output as is as the corrected encoder pulse signal PE.

Further, the speed error signal SS has a value corresponding to the difference between the target speed and the rotational speed of the spindle motor SH.

The sum of these phase error signals SB and speed error signals SS is
It is output to the motor drive circuit 29 as an error signal CC, and thereby the motor drive circuit 29 controls the spindle motor S.
Corresponding to the maximum acceleration that can be applied to M, the drive signal CD
The value of is changed in the direction of speed increase.

As a result, the spindle motor S speeds up with maximum acceleration.

As the speed of the spindle motor SM increases, the frequency of the encoder pulse signal SH increases, so the speed error signal SS gradually decreases6. When the rotational speed of the spindle motor SH approaches the target rotational speed, the value of the phase error data DB output from the up/down counter 23 also gradually decreases.

When the rotational speed of the spindle motor SH matches the target speed, the reference pulse signal PR is generated as shown in FIGS.
and encoder pulse signal SH have the same waveform, and the reference pulse signal PR and encoder pulse No. 4'R SE
The interval between the rising edges of , that is, the phase error, takes a value smaller than the pulse width. Note that FIG. 2 shows a state in which the phase of the reference pulse signal PR is advanced, and FIG. 4 shows a state in which the phase of the encoder pulse signal SH appears to be advanced.

In this state, the rising edges of the reference pulse signal PR and the encoder pulse signal SH occur at the same period and at different timings, so the phase error data DB of the up/down counter 23 is -1, 0, 1. It will take on one of the values.

Therefore, after setting the rotation speed in process lO1, the control unit 20 inputs the phase error data DE every time it detects the falling edge of the reference pulse signal PR (determination 102). It is checked whether the value is between -1 and 1 (judgment 104), and by repeating the processes from judgment 102 to judgment 104 until the phase error data DE reaches a value between -1 and I, the spindle motor SH is Wait until the rotation speed matches the S speed.

If the result of judgment 104 is vIES, then the rotational speed of the spindle motor SH is in a state that matches the target rotational speed, so changes in the state of the encoder pulse signal SH should be monitored (No loop of judgment 105). If the result of judgment 105 is YES, wait until time Δt1 has elapsed from the state change timing (process 106).
, it is again monitored whether or not there is a change in the state of the encoder pulse signal SH after the end of processing 106 until the time Δt2 has elapsed (No loop of judgments 107 and 108).

Here, in a state where the encoder pulse signal SE is not missing, the encoder pulse signal SE has a period from the time Δt1 has elapsed since one state change occurs until 1 hour Δt2 has elapsed. Since there is always a common state change (see Figures 2 (a) to (e) and Figures 4 (a) to (s)), the result of decision 1ioa will never be YES, and the result of decision 107 will not be YES. The result is YES.

Further, if the result of judgment 107 is YES, processing 106
Return to

On the other hand, when the rising and falling parts of the encoder pulse signal SR are missing, FIGS.
) and as shown in FIGS. 6(a) and 6(e), the next state change cannot occur between the time Δt1 has elapsed since the previous state change and the time Δt2 has elapsed. The result of judgment 108 is YES, and in this case, the control unit 2o outputs the complementary pulse signal SC of logical H level whose pulse width matches the time Δt2 (process 10).
9).

As a result, the state of the correction encoder pulse signal PE output from the exclusive OR circuit 21 changes once in accordance with the signal change of the complementary pulse signal sc, so that the down-count operation of the up-down counter 23 is always performed by one count. This is executed so that the phase error data DH does not deviate from the range of -1 to 1.

As a result, after the rotational speed of the spindle motor SM matches the target rotational speed, the phase error data DI! The value of is -1
Since the rotational speed of the spindle motor SH does not deviate from the range of 1 to 1, the rotational speed of the spindle motor SH is prevented from unnecessarily changing the rotational speed of the spindle motor SM.

In addition, this processing 106, judgments 107 and 108, and
The processing loop of process 109 is continuously executed until the rotational speed of the spindle motor SH is changed.

Note that the rotational speed of the spindle motor SH is mainly changed when moving a track accessed by an optical disk driven at a constant linear velocity and when starting/stopping the spindle motor SM.

As described above, in this embodiment, the spindle motor S
When the rotational speed of H is controlled to the target value, the time interval between state changes of the encoder pulse signal SE is monitored to detect a lack of the encoder pulse signal SH, and a complementary pulse signal is generated to complement the missing encoder pulse signal SE. Since the encoder pulse signal SE is corrected by the complementary pulse signal Sc, the phase error signal SB is prevented from exceeding a certain value, and as a result, the spindle motor S? Rotational fluctuations in l are prevented.

By the way, in the above-mentioned embodiment, by measuring the time interval of the state change of the encoder pulse signal SH using software, the omission of the encoder pulse No. 1 sE is detected, and the complementary pulse signal SC is outputted to replace the encoder pulse signal SE.
This correction part can be realized using a logic circuit.

Such an embodiment is shown in FIG.

Here, the encoder pulse correction circuit EC shown in FIG.
1 is an element inserted between the pulse encoder PE and the down count input end of the up/down counter 23 in FIG. 1, and the same parts as in FIG. 1 are given the same reference numerals.

In the same figure, the encoder pulse signal SE is generated by a PLL (Phase Loc) that is phase-synchronized with the encoder pulse signal SH and generates a clock signal cp having a frequency (2f) twice the frequency (f) of the encoder pulse signal SE.
kedLoop) Circuit 30. Encoder pulse signal S
It is added to one input terminal of a complementary pulse generation circuit 40 which detects the absence of E and outputs a complementary pulse signal SK, and an exclusive OR circuit 21.

In the complementary pulse generation circuit 40, the clock signal CP output from the PLL circuit 30 is inverted via an inverter circuit 41 and applied to the clock input terminals of D flip-flops 42 and 43, and is further applied via an inverter circuit 44. The signal is inverted and applied to the clock input terminal of the D flip-flop 45.

Therefore, the D flip-flops 42 and 43 store the state of the data input end in synchronization with the falling edge of the clock signal CP, and the D flip-flop 45 stores the state of the data input end in synchronization with the rising edge of the clock signal CP. The state of the data input end is stored.

An encoder pulse signal SE is applied to the data input end of the D flip-flop 42, and a signal at the output end Q of the D flip-flop 42 is applied to the data input end of the D flip-flop 43.
and one input terminal of the exclusive OR circuit 46.

The signal at the output terminal Q of the D flip-flop 43 is applied to the other input terminal of the exclusive OR circuit 46, and the output signal of the exclusive OR circuit 46 is applied to the output terminal Q of the D flip-flop 45.
The signal is applied to the data input terminal of , and is inverted via an inverter circuit 47 and applied to one input terminal of an AND circuit 48 .

The signal at the output terminal Q of the D flip-flop 45 is applied to the other input terminal of an AND circuit 48, and the output signal of this AND circuit 48 is applied to one switching input terminal of the switch 50 as a complementary pulse signal SK. It has been added to 51.

The other switching input terminal 52 of the switching device 50 is connected to the ground level, and the signal at the common connection terminal 53 is as follows.
It is applied to the other input terminal of the exclusive OR circuit 21 as a complementary pulse signal SC.

With the above configuration, the switching signal C is output from the control unit 20 until the spindle motor SM reaches the target rotational speed.
B, the switch 50 selects the switching input terminal 52, and thereby the other input terminal of the exclusive OR circuit 21 is fixed at the logic L level, and the encoder pulse signal S
E is directly outputted as a correction pulse signal PR via the exclusive OR circuit 21.

Furthermore, when the spindle motor SM reaches the target speed, the switching signal CB causes the switching device 50 to select the switching input terminal 51, thereby enabling the operation of the complementary pulse generation circuit 40.

In the complementary pulse generation circuit 40, as shown in FIGS. 8(a) to (i), the encoder pulse signal SR is sequentially stored in the D flip-flop 42 at the falling timing of the clock signal CP, and is stored in the D flip-flop 43. The output signal of the D flip-flop 43 is sequentially stored at the falling timing of the clock signal CP, and the exclusive OR circuit 4
6 compares the output signal of the D flip-flop 42 and the output signal of the D flip-flop 43, and raises the output signal to a logic H level if they do not match.

Therefore, when the encoder pulse signal SE is continuously output, the outputs of the D flip-flop 42 and the D flip-flop 43 are always different, so the output of the exclusive OR circuit 46 is maintained at the logic 11 level. ,
As a result, the output signal of the inverter 47 is maintained at the logic L level, so in that state, the complementary pulse signal S output from the 5-AND circuit 48 is maintained at the logic L level.

As a result, when the encoder pulse signal SE is continuously output, the encoder pulse signal S pi becomes
It is output via the exclusive OR circuit 21 as a corrected encoder pulse signal PH.

If the rising edge of the encoder pulse signal SE is missing, the output signal of the 0 flip-flop 42 and the output signal of the D flip-flop 43 will match from the falling timing of the clock signal CP immediately after the rising timing of the missing rising edge. , the output signal of the exclusive OR circuit 46 falls to the logic L level.

On the other hand, the D flip-flop 45 is connected to the exclusive OR circuit 4
The output signal of 6 changes to the logic level at the rising timing of the clock signal CP immediately after falling to the logic L level.

Therefore, the two inputs of the AND circuit 48 both change to logic 1 level after the output signal of the exclusive OR circuit 46 changes to logic L level until the clock signal CP rises next. At this timing, a complementary pulse signal S having a pulse width of 172 equal to the encoder pulse signal SH is outputted, and is outputted to the exclusive OR circuit 21 via the switch 50 as a complementary pulse signal SC.

As a result, the exclusive OR circuit 21 outputs a corrected encoder pulse signal PE formed by combining the complementary pulse signal SC with the encoder pulse signal SE.

Note that even when the falling edge of the encoder pulse signal SE is missing, the complementary pulse signal SC is similarly output to the exclusive OR circuit 21.

In this way, a missing encoder pulse signal SH is detected and a complementary pulse signal SC for interpolating it is output.

Note that the present invention can be similarly applied to spindle motors other than those shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, a missing encoder pulse signal is detected based on the signal change time interval of the encoder pulse signal, and a complementary pulse signal is formed to complement the missing encoder pulse signal. This complementary pulse signal is then combined with the encoder pulse signal, so even if the encoder pulse signal becomes abnormal due to dust etc. adhering to the encoder plate, the encoder pulse signal can be corrected based on the complementary pulse signal. Therefore, it is possible to obtain the effect that rotational fluctuations of the spindle motor are prevented.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a control device according to an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining an example of operation in a state where encoder pulse signals are not missing, and FIG. 3 is a block diagram showing a control device according to an embodiment of the present invention. A flowchart showing an example of the processing to be executed, FIG. 4 is a waveform diagram showing another example of operation in a state where the encoder pulse signal is not missing, and FIG. 5 is a waveform diagram showing an example of the operation when the encoder pulse signal is missing. Figure 6 is a waveform diagram showing another example of operation when the encoder pulse signal is missing;
The figure is a block diagram showing an example of an encoder pulse correction circuit, FIG. 8 is a waveform diagram for explaining the operation of the circuit of FIG. 7, and FIG. 9 is a schematic sectional view showing an example of a spindle motor.
FIG. 10 is a waveform diagram for explaining the general operation of the conventional device, and FIG. 11 is a waveform diagram for explaining the problems of the conventional device. 20... Control unit, 21.46... Exclusive OR circuit, 22... Reference signal generation circuit, 23... Up/down counter, 24, 25... Frequency/voltage converter,
26... Digital/analog converter, 27... Deviation calculator, 28... Adder, 29... Motor drive circuit, 3O-PLL (Phase Locked Loop
) circuit, 40... complementary pulse generation circuit, 41, 44,
47...Inverter circuit, 42, 43.45...D
Flip-flop, 48...AND circuit, 50...
Switch. fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig fig.

Claims (1)

[Claims] A spindle motor control device that rotationally controls a spindle motor that rotationally drives a disk storage medium includes a pulse encoder that outputs an encoder pulse signal as the spindle motor rotates, and an encoder pulse that outputs an encoder pulse signal based on the signal change time interval of the encoder pulse signal. A pulse signal loss detection means for detecting a signal loss; a complementary pulse signal generation means for generating a complementary pulse signal when the pulse signal loss detection means performs a detection operation; and correction by combining the complementary pulse signal and the encoder pulse signal. A control device for a spindle motor, comprising a pulse signal synthesizing means for generating an encoder pulse signal.