JPH04217892A - Circuit for processing spindle error signal - Google Patents

Abstract

PURPOSE:To prevent a decline in the reproducing error rate and, at the same time, to appropriately control the drive of a motor. CONSTITUTION:At the time of closing spindle servo, the occurrence of cogging which has been an issue is suppressed by directly outputting the output of an amplifier 12 which is an unprocessed signal from an amplifier 15 so that this spindle error signal processing circuit can make the same operations as the conventional motor rotating speed detection circuit does. At the time of frequency measurement, on the other hand, the mean value of driving voltages charged in the capacitor C1 of an LPF 13 which are processed signals is given to each Hall element 1, 2, and 3 as a bias. Therefore, the bias of each Hall element 1, 2, and 3 is stabilized since the same operations as the conventional motor rotating speed control circuit are performed. In addition, since the chattering of an FG pulse is suppressed and the driving voltage to be charged in the capacitor C1 is the mean value of driving voltages immediately before a control signal is switched between an 'H' and 'L' levels, the rotating speed of a spindle is set to the mean value.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a spindle error signal processing circuit that processes spindle error signals for a motor rotation speed control circuit that appropriately controls the rotation speed of a brushless spindle motor based on a spindle error signal. Regarding circuits.

0002

2. Description of the Related Art Generally, in devices such as laser disc (LD) players that play optical discs with a large diameter, the load applied to the spindle motor is relatively high, so a circuit such as that shown in FIG. The structure is taken. That is, the outputs from the Hall elements 1, 2, and 3 to which the fixed bias Vcc1 is applied are supplied to the comparators 4, 5, and 6, respectively. Here, the outputs supplied to each comparator 4, 5, 6 are (HA(+
), HA(-)), (HB(+), HB(-)), (H
C(+), HC(-)). In addition, the outputs of the comparators 4, 5, and 6 are Ha, Hb, and Hc, respectively.
It is.

[0003] The output of each comparator 4, 5, 6 (Ha
, Hb, Hc) are made into FG outputs by the arithmetic circuit 7 and are also output to the phase switching pulse generation circuit 8. The phase switching pulse generation circuit 8 selects each transistor group TrA, TrB, T based on the above comparator output.
Turn rC on/off. At this time, the direction of the current flowing through each phase (coil) of the brushless three-phase Hall motor 9 based on the combination of each comparator output during forward rotation and reverse rotation is as shown in FIG. 3, for example. Further, the spindle error correction circuit 10 is connected to the emitter side of the NPN transistors TrA2, TrB2, TrC2 of each transistor group TrA, TrB, TrC.
, TrB2, TrC2, spindle error correction is performed.

In the motor rotation speed control circuit having such a configuration, a fixed bias Vcc1 is applied to each Hall element 1, 2, 3.
is given, the outputs of comparators 4, 5, and 6 (Ha, Hb
, Hc), it is possible to easily obtain an FG (synchronous) output based on the calculation result by the calculation circuit 7. On the other hand, when attempting to reproduce a small diameter disc such as a CD, the load becomes small and the rotation fluctuates at the phase switching point, which tends to cause so-called cogging. For this reason, when a motor rotation speed control circuit with such a configuration is applied to a CD player, the time axis of the RF signal fluctuates due to the occurrence of cogging, causing so-called jitter, which reduces the playback error rate. .

On the other hand, in devices for reproducing small-diameter optical discs such as CDs, a circuit configuration such as that shown in FIG. 4, for example, is used because a relatively little load is applied to the spindle motor. In other words, each Hall element 1, 2
, 3 is not fixed, and the spindle error is input to the bias of each Hall element 1, 2, 3. As a result, the output voltage of each Hall element 1, 2, and 3 varies depending on the value of the spindle error. These Hall element outputs are then calculated by an analog addition/subtraction circuit 10A. Here, the calculation formula by the addition/subtraction circuit 10A is as follows. La = (HA(-)+HB(+))-(HA(+)+
HB(-))Lb =(HB(-)+HC(+))-(
HB(+)+HC(-))Lc =(HC(-)+HA
(+))-(HC(+)+HA(-)) After these calculation results are amplified, the three-phase Hall motor 9 is driven based on these values. As a result, the spindle error is +
When increasing to the + side, the Hall bias increases accordingly to the + side. Therefore, since the amplitude of the output of each Hall element 1, 2, and 3 increases, the amplitude of the output of the calculation result also increases, and the rotational speed of the three-phase Hall motor 9 increases. Conversely, when the spindle error increases toward the negative side, the Hall bias increases accordingly. Therefore, since the amplitude of the output of each Hall element 1, 2, and 3 decreases, the amplitude of the output of the calculation result also decreases, and the rotational speed of the three-phase Hall motor 9 decreases.

[0006] In this way, based on the analog calculation results, 3
Since the rotational speed of the phase Hall motor 9 is controlled, there is an advantage that cogging is less likely to occur, unlike the above-mentioned motor rotational speed control circuit. Therefore, jitter is less likely to occur in the RF signal, and the error rate increases. However, the drawback is that the bias of each Hall element 1, 2, and 3 is varied in proportion to the spindle error, so when FG is generated from the value obtained by comparing the output of each Hall element 1, 2, and 3, each When the bias of the Hall elements 1, 2, and 3 becomes low (or becomes negative), the comparator value fluctuates and so-called chattering occurs. Therefore, the FG signal will be accurate only when the bias of the Hall element is stable during acceleration/deceleration, etc., but when playing a disc with a large eccentricity and the spindle servo is closed, the FG signal will be accurate. , the chattering becomes so intense that it becomes unusable.

[0007]

[Problems to be Solved by the Invention] As described above, in the former type of conventional motor rotation speed control circuit described above, phase switching timing is generated by a Hall element and the motor is rotated by a switching method, so that cogging occurs. Especially when applied to a device that plays back CDs with a light load, jitter is likely to occur in the RF signal, resulting in a reduction in the playback error rate. On the other hand, in the latter case, the rotation speed of the motor is controlled by controlling the bias of the Hall element, so the bias of the Hall element is constantly changing. For this reason, when the FG signal is obtained from a value obtained by comparing the output of the Hall element, chattering occurs, making it impossible to accurately measure the motor's rotation speed and making it difficult to perform accurate motor drive control. It becomes impossible.

The present invention has been made in response to the above-mentioned circumstances, and provides a motor rotation speed control circuit that can prevent a reduction in the playback error rate and perform appropriate motor drive control. The purpose is to

[0009]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a motor rotation speed control circuit that appropriately controls the rotation speed of a brushless spindle motor based on a spindle error signal. In a spindle error signal processing circuit that processes error signals,
a first spindle error signal output means that holds a DC component obtained by removing a high frequency component from the spindle error signal and outputs the unprocessed spindle error signal; and a first spindle error signal output means that outputs the DC component as a spindle error signal. a spindle error signal outputting means for operating the first spindle error signal outputting means when the spindle servo is closed, and operating the second spindle error signal outputting means when measuring the frequency; It is characterized by comprising a signal output control means.

0010

[Operation] In the spindle error signal processing circuit of the present invention,
The spindle error signal output control means operates the first spindle error signal output means when the spindle servo is closed. The first spindle error signal output means controls the rotation speed by directly outputting the input spindle error signal and applying it as a bias to the Hall element, so the drive current becomes smooth and cogging is prevented. Occurrence is prevented. On the other hand, during frequency measurement, the spindle error signal output control means
The spindle error signal output means is operated. The second spindle error signal output means samples the DC component from which the high frequency component is removed from the first spindle error signal, holds the value immediately before switching to the second spindle error signal, and stores this value. Output as spindle error signal. As a result, a fixed spindle error signal is output, thereby preventing chattering in the FG signal output.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, details of embodiments of the present invention will be explained with reference to the drawings. FIG. 1 shows an embodiment of the spindle error signal processing circuit of the present invention, and the output from this spindle error signal processing circuit is transmitted to each Hall element 1 of the conventional motor rotation speed control circuit shown in FIG. , 2, and 3. As shown in the figure, the spindle error signal processing circuit includes an amplifier 12 that amplifies the input spindle error. A non-inverting input terminal of an amplifier 14 is connected to the output side of the amplifier 12 via an LPF 13 consisting of a FET Q2, a resistor R1, and a capacitor C1. On the output side of the amplifier 14,
The non-inverting input terminal of amplifier 15 is connected via FETQ1.

The spindle error signal processing circuit also includes a transistor Q3 to which a sample hold control signal is input. Transistor Q3
The collector side of is connected to the gate of FETQ1 via diode D1, and transistor Q4 is connected to the gate of FETQ1 via diode D1.
The base side of is connected. The collector side of transistor Q4 is connected to the gate of FET Q2 by diode D2.
connected via.

The spindle error signal processing circuit configured as described above operates as follows. First, when the spindle servo is closed, an H level sample hold control signal is input to the base of transistor Q3. This turns off the transistor Q3, cutting off the supply of current to the base of the transistor Q4, thereby turning off the transistor Q4. Furthermore, due to this, the gate voltage of FETQ1 becomes VEE
FET Q1 turns off because the voltage drops to . At this time, current from the reference power supply Vcc2 is supplied to the gate of FETQ2, so FETQ2 is turned on. Therefore, the output of amplifier 12 is applied to amplifier 1 via resistor R2.
This amplifier 12
As an unprocessed spindle error signal, each Hall element 1, 2 of the conventional motor rotation speed detection circuit shown in FIG.
, 3.

At this time, since FET Q2 is turned on, the spindle error signal that is the output of the amplifier 12 has its eccentric component removed by the LPF 13, and then becomes the average of the drive voltage, which is the signal of the removed component. The value is charged to capacitor C1. On the other hand, when measuring the frequency from the FG signal that is the output of the digital arithmetic circuit 11 shown in FIG. 4, the sample-and-hold control signal to be input to the transistor Q3 is set to L level, and the transistor Q3 is turned on. As a result, the reference power supply V
Since the voltage of cc1 is supplied to the gate side of FETQ1 and the base side of transistor Q4, FETQ1
And transistor Q4 is turned on. For this reason, FET
Since the voltage on the gate to Q2 drops to VEE, FE
TQ2 is turned off. Therefore, the average value of the drive voltage charged in the capacitor C1, which is the processed signal, is output from the amplifier 15 using the amplifier 14 as a buffer. At this time, the spindle motor rotates at the average value of the rotation speed immediately before the control signal switches from the H level to the L level.

In this way, when the spindle servo is closed, the output of the amplifier 12, which is an unprocessed signal, is directly output from the amplifier 15, so the circuit is the same as the conventional motor rotation speed detection circuit shown in FIG. An action is taken. Therefore, as described above, the occurrence of cogging is suppressed. On the other hand, during frequency measurement, the average value of the drive voltage charged in the capacitor C1 is given as a bias for each Hall element 1, 2, and 3. As a result, the same operation as the conventional motor rotation speed detection circuit shown in FIG. 2 is performed, so that the bias of each Hall element 1, 2, and 3 is stabilized, and chattering of the FG pulse is suppressed. Also,
Since the driving voltage to be charged to the capacitor C1 is the average value immediately before switching between H and L of the control signal,
The spindle rotation speed is the average value. As a result, the spindle rotation is kept constant regardless of eccentricity, making it possible to accurately measure frequency using FG pulses.

That is, for example, when measuring the linear velocity of a CD, it is carried out as follows. First, the time codes t1 and t2 at two different points and the spindle rotational speeds n1 and n2 when the spindle is locked at these points are measured, and the linear velocity V is obtained from the following calculation formula. However, t2 > t1, π=3.14..., P=track pitch, and k=constant. At this time, if you fetch the time code when the spindle is locked, t1, t2
can be obtained relatively easily, but the spindle rotation speed n1
, n2 must be accurately measured using an FG pulse or the like.

The accuracy of linear velocity measurement using this method depends on how accurately the rotational speed can be measured. Therefore, if accurate linear velocity is obtained, the accuracy of calculating the number of tracks from the target timecode and the current timecode at the time of search will improve, improving the accuracy of the search and speeding up the search. I can figure it out. Therefore, when the spindle is locked and the time code (t1 or t2) can be read, the control signal to transistor Q3 is switched from H level to L level. Next, the spindle rotation speed (n1 or n2) is measured using the FG pulse, and the control signal is switched from the L level to the H level again. Perform this series of operations at two points on the inner and outer circumference of the CD.
Perform this as an initial measurement when starting up the system.

In this way, in this embodiment, when the spindle servo is closed, the output of the amplifier 12, which is an unprocessed signal, is directly output from the amplifier 15, so that the conventional motor shown in FIG. The same operation as the rotation speed control circuit is performed. This suppresses the occurrence of cogging, which has been a problem in the past. Further, during frequency measurement, the average value of the drive voltage charged in the capacitor C1 of the LPF 13, which is the processed signal, is applied as a bias to each Hall element 1, 2, and 3. As a result, the same operation as the conventional motor rotation speed control circuit shown in FIG. 2 is performed, so that the bias of each Hall element 1, 2, and 3 is stabilized. Furthermore, since the chattering of the FG pulse is suppressed and the drive voltage to be charged to the capacitor C1 is the average value immediately before switching between H and L of the control signal, the spindle rotation speed is set to that average value. Therefore, since the spindle rotation is constant regardless of eccentricity, accurate frequency measurement using FG pulses is possible.

[0019]

[Effects of the Invention] As explained above, the spindle error signal processing circuit of the present invention prevents the occurrence of cogging when the spindle servo is closed, and prevents the occurrence of chattering when measuring the frequency. Therefore, in addition to preventing a decrease in the playback error rate,
Appropriate motor drive control can be performed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a spindle error signal processing circuit of the present invention.

FIG. 2 is a circuit diagram showing an example of a conventional motor rotation speed control circuit.

3 is a diagram showing the direction of current flowing through each phase (coil) of the three-phase Hall motor according to a combination of comparator outputs during forward rotation and reverse rotation of the motor rotation speed control circuit of FIG. 2; FIG.

FIG. 4 is a circuit diagram showing another example of a conventional motor rotation speed control circuit.

[Explanation of symbols]

1, 2, 3 Hall element 4, 5, 6 Comparator 10A addition/subtraction circuit 11 Arithmetic circuit 12 Amplifier 13 LPF 14 Amplifier 15 Amplifier Q1, Q2 FET Q3, Q4 transistor

Claims (1)

[Claims] 1. A spindle error signal processing circuit that processes the spindle error signal for a motor rotation speed control circuit that appropriately controls the rotation speed of a brushless spindle motor based on a spindle error signal. a first spindle error signal output means that holds a DC component from which a high frequency component is removed from the signal and outputs the unprocessed spindle error signal; and a second spindle that outputs the DC component as a spindle error signal. error signal output means; and spindle error signal output control that operates the first spindle error signal output means when the spindle servo is closed and operates the second spindle error signal output means when measuring the frequency. A spindle error signal processing circuit comprising means.