JP3139752B2 - Disc playback device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Purpose of the Invention] (Industrial application field) The present invention relates to an optical disc reproducing apparatus such as a CD-ROM drive.

(Prior Art) In general, in an optical recording / reproducing apparatus, information recorded on a disk is read by a pickup. However, during position control, that is, during data reading, the pickup needs to be moved at a low speed. That is, when moving the pickup to the target position, it is necessary to move the pickup at high speed.

For example, in a CD-ROM drive, the pickup must move about 30 mm in about 60 minutes during position control. Therefore, ultra-low speed control performance of 30mm / 3600sec 300.008mm / sec is required.

On the other hand, during speed control, for example, a distance of 30 mm
It is necessary to move in seconds. In this case, the moving speed is required to be ultra-high speed control of 30mm / 0.2sec0.2150mm / sec.

As described above, the movement speed of the pickup during the position control and the speed control is in the ratio of 1: 18000.

By the way, in the conventional recording / reproducing apparatus, a pickup feeding DC motor is connected to a pinion gear, the pickup is attached to a rack gear meshing with the pinion gear, and the pickup is fed by driving the DC motor. I have.

Since the maximum rotation speed of such a DC motor is about 3000 rpm, in order to send a distance of 30 mm in 0.2 seconds, select a gear ratio that moves 30 mm in 3000 rpm x 0.2 seconds / 60 seconds = 10 rotations Will be.

However, if you do not change the gear ratio,
It will rotate 10 times in 60 minutes. Therefore, in one second, 10 rotations / 3600 seconds ≒ 0.003 rotations is used, which is an ultra-low rotation.

In this case, control cannot be performed with a simple DC motor.

In order to solve such a problem, the applicant of the present invention has proposed to apply speed feedback to a DC motor to enable ultra-low speed control.
81956, Japanese Patent Application No. 1-81959, and Japanese Patent Application No. 1-81376.

(Problems to be Solved by the Invention) In Japanese Patent Application No. 62-260165, speed feedback is performed to a linear motor, and in Japanese Patent Application Nos. 1-81956, 1-81959 and 1-81376, a speed generator is provided. Is fed back to the motor.

That is, the technique disclosed by the applicant of the present application detects, for example, the drive of a rotary motor for pick-up feed using a Hall element or the like, and outputs a signal output from this Hall element, that is, outputs at a different frequency according to the rotation speed of the motor. By differentiating the given position signal, a speed voltage that changes according to the rotation speed of the motor is obtained, and speed feedback is realized.

By the way, in such a method, the speed voltage is one pair.
When there is a large difference such as 18000, the following inconvenience occurs.

For example, if the circuit constants are set so that a speed voltage of 5 V is generated during speed control, the speed voltage during data reading is 5/18000 ≒ 0.27 mV, which is smaller than the input offset voltage of a general-purpose operational amplifier. Will also be smaller. Therefore, sufficient performance cannot be obtained unless such offset adjustment of the operational amplifier is performed.

Also, in recent years, when the disk playback device has been used more portablely and the battery is driven, etc., the power supply voltage is low. The voltage will drop.

The present invention has been made in view of such a problem, and an object thereof is to generate an appropriate speed voltage during speed control (during high-speed movement) and during position control (during low-speed movement). Another object of the present invention is to provide a disk reproducing apparatus capable of stably sending a pickup with high performance.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a disk reproducing apparatus of the present invention reads information recorded on a disk via a pickup as described in claim 1. In a disc reproducing apparatus having a pickup feed servo circuit for reading, a driving unit for driving the pickup in a radial direction of the disc, and a moving speed of the pickup driven by the driving unit is detected and a speed corresponding to the moving speed is detected. A speed detecting means for outputting a signal, a rectifying circuit including at least an operational amplifier for rectifying the speed signal output by the speed detecting means, and a plurality of gain switches respectively arranged before and after the rectifying circuit. Circuit and
Mode switching means for switching between a first control mode for track jump of the pickup and a second control mode for tracking servo, a speed signal output from a gain switching circuit subsequent to the rectifier circuit, and the mode Means for comparing a reference speed signal corresponding to the control mode selected by the switching means and feeding back the difference signal to the driving means, and a speed signal supplied to the operational amplifier of the rectifier circuit, wherein The control mode selected by the mode switching means so that the control mode falls within the dynamic range of the operational amplifier in the control mode and satisfies the minimum limit value of the offset voltage of the operational amplifier in the tracking servo in the second control mode. Control means for changing the gains of the gain switching circuits before and after the rectifier circuit in accordance with Characterized in that it.

According to a second aspect of the present invention, there is provided a disk reproducing apparatus according to the first aspect, wherein the speed detecting unit detects the position signal of the pickup as a unit. Means for differentiating the position signal to continuously obtain a velocity signal.

According to a third aspect of the present invention, in the disk reproducing apparatus according to the first aspect, the driving unit includes a brushless motor, and the speed detecting unit includes a brushless motor. It has a position detecting means for detecting a position signal, and means for differentiating the position signal detected by the position detecting means and outputting a speed signal.

(Operation) In the present invention, the gain distribution of the circuit is switched between the speed control and the position control by changing the gain of the moving speed signal of the pickup during the speed control and the position control, and the optimum speed voltage is generated. Let it.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a disk reproducing apparatus according to one embodiment of the present invention.

As shown in FIG. 1, the recording / reproducing apparatus includes a motor 1, a pickup 3, a tracking servo circuit 5, an actuator position error detection circuit 7, position detectors 9a and 9b, gain switches 11a and 11b, differentiators 13a and 13b. , Rectifiers 15a, 15b,
Adder 17, Gain switch 19, Controller 21, Counter 2
3. It has a position error detection circuit 25, a switch 27, a comparator 29, and a power amplifier 31.

FIG. 2 is a diagram showing a schematic configuration of a reading portion of the disk 33. The disk 33 on which information is recorded is rotated by a disk motor 35. A motor 1 for moving a pickup 3 for reading detailed information recorded on the disk 33
Rotates the pinion gear 41. This pinion gear 41
Are geared with the rack gear 39, and when the motor 1 rotates, the pickup 3 moves in the radial direction of the disk 33.

 The position detectors 9a and 9b detect the amount of rotation of the motor 1.

FIG. 3 is an elevation view near the position detectors 9a and 9b, and FIG. 4 is a plan view near the position detectors 9a and 9b.

As shown in the figure, a magnet 47 and a pinion gear 41 are mounted on a motor shaft 45 of the motor 1 mounted on the motor mounting base 43.

When the magnet 47 rotates, the position detectors (Hall elements) 9a and 9b output a voltage corresponding thereto. The output voltage is set so that the phase is shifted by 90 degrees in electrical angle.

Therefore, such position detectors 9a and 9b output position signals at a frequency corresponding to the rotation speed of the motor 1.

The differentiators 13a and 13b differentiate the position signals output from the position detectors 9a and 9b to obtain a speed voltage that changes according to the rotation speed of the motor 1, that is, a speed voltage corresponding to the moving speed of the pickup 3. Output a signal.

In FIG. 1, a tracking servo circuit 5 performs tracking servo of the pickup 3.

The actuator position error detection circuit 7 sends an output signal of the tracking servo circuit 5 to the switch 27.

FIG. 5 is a circuit diagram showing a configuration of a main part of the disk reproducing apparatus shown in FIG. In FIG. 5, the pickup 3, the tracking servo circuit 5, and the actuator position error detection circuit 7 are omitted. In FIG. 5, circuits not shown in FIG. 1 are also described.

The output signal of the position detector 9a is input to the operational amplifier 51a, and the output signal of the operational amplifier 51a is input to the gain switch 11a and the waveform shaping circuit 12a.

Operational amplifier 53a, capacitor 55a, transistor 61a,
The resistors 57a, 59a, and 63a form a gain switch 11a and a differentiator 13a.

The gain switch 11a and the differentiator 13a differentiate the output signal of the operational amplifier 51a, and the gain when differentiating is switched by the controller 21.

Assuming that the capacitance of the capacitor 55a is C55a and the resistance values of the resistors 57a and 59a are R57a and R59a, the transistor is used at the time of speed control.
61a is turned off. In this case, the differential constant of the differentiator composed of the operational amplifier 53a is C55a · R59a.

At the time of position control, the transistor 61a is turned on. In this case, the differential constant of this circuit is C55a / R57a / R59a / (R57a + R59a).

The waveform shaping circuit 12a includes an operational amplifier 65a and resistors 67a and 69a.

This waveform shaping circuit 12a shapes the waveform of the output signal of the operational amplifier 51a.

The rectifier 15a includes an operational amplifier 71a, resistors 73a, 75a, 77a, 7
9a, comprising a transistor 81a.

The rectifier 15a rectifies the output signal of the differentiator 13a.

When the transistor 81a is on and the resistance 73a is equal to the resistance 77a, the operational amplifier 71a functions as an inverting amplifier with a gain of “−1”. When the transistor 81a is off, the operational amplifier 71a has a non-gain of “1”. Functions as an inverting amplifier.

Position detector 9b, gain switch 11b, differentiator 13b, rectifier 15
The configuration of b is the same as the above-described position detector 9a, gain switch 11a, differentiator 13a, and rectifier 15a.

 The adder 17 includes resistors 83a and 83b and a connection point 85.

The adder 17 adds the output signals of the rectifiers 15a and 15b.

 The gain switch 19 includes resistors 87 and 88 and a switch 89.

The gain switch 19 converts the gain of the output signal of the adder 17 according to an instruction from the controller 21.

Assuming that the resistance values of the resistors 87 and 88 are R87 and R88, respectively, when the switch 89 is off, the resistance value of the gain switch 19 is R87, but when the switch 89 is on, the resistance values are R87 and R88. / (R87 + R88).

The controller 21 switches between a speed control mode for track jump in the pickup 3 and a position control mode for tracking servo, and according to the selected control mode, a gain switch 11a preceding the rectifiers 15a and 15b. , 11b and the gain switch 19 at the subsequent stage.

Therefore, for example, the controller 21
The gain distribution between the gain switches 11a and 11b and the gain switch 19 is changed by the switch control signal SW, and the switch 27 is set.
Is performed.

The counter 23 includes 8-bit counters 23a and 23b that count down.

The position error detection circuit 25 converts the output signals of the counters 23a and 23b into an analog signal using a ladder resistor.

The switch 27 includes a transistor 27a, an inverter 119, and a switch 27b.

When the switch control signal SW is "1", the transistor 27a is turned on, and the output signal of the position error detection circuit 25 is sent to the comparator 29.

The switch control signal SW is connected to the inverter 11
Since the signal is sent to the switch 27b via the switch 9, the switch 27b is open when the switch control signal SW is "1".

When the switch control signal SW is “0”, the transistor 27a is turned off and the switch 27b is turned on.

The comparator 29 and the power amplifier 31 are composed of the operational amplifier 91, the resistor 93, and the capacitors 95 and 97.

The operational amplifier 91 compares the output signal of the gain switch 19 with the reference speed signal, amplifies the signal, and sends the amplified signal to the motor 1.

The AND circuit 101 calculates the logical product of the output signals of the MAX terminals of the counters 23a and 23b, and inputs the logical product to the STOP terminal of the controller 21 as a counter-up signal.

The operational amplifier 103 converts impedance.

The track jump direction switching circuit 105 is connected to the operational amplifier 1
07, a transistor 109, and resistors 111, 113, 115, and 117.

The track jump direction switching circuit 105 switches the track jump direction according to a signal output from the F / R terminal of the controller 21.

When the F / R signal is “1”, the transistor 109 is turned on. Therefore, if the resistances 111 and 115 are equal, the operational amplifier
107 functions as an inverting amplifier with a gain of “−1”. F / R
When the signal is “0”, the transistor 109 is turned off, so that the operational amplifier 107 functions as a non-inverting amplifier having a gain of “1”.

 Next, the operation of the present embodiment will be described.

First, the schematic operation of this embodiment will be described with reference to FIGS. 1, 4, and 6. FIG.

FIG. 6 is a waveform diagram of a signal of each section in FIG. In the figure, CCW and CW indicate different rotation directions of the motor 1, respectively.

When the motor 1 rotates, the magnet 47 rotates accordingly, and signals H1P and H2P are output from the terminals of the position detectors 9a and 9b. In addition, the signals H1N, H2N
Is output.

After these signals are subtracted by the operational amplifiers 51a and 51b, the gains are changed by the gain switches 11a and 11b and the differentiators 13a and 13b.
The signal is differentiated by a predetermined gain, and signals H1D and H2D are output.

Also, the waveform is shaped by the waveform shaping circuits 12a and 12b,
The signals H1S and HS2 are output. Further, the signals H1D and H2D are rectified by the rectifiers 15a and 15b, respectively, so that the signals H1V and H2V
Is output.

These signals H1V and H2V are added in an adder 17 and the gain is changed by a gain switch 19, then compared with a speed reference signal by a comparator 29, amplified by a power amplifier 31, and fed back to the motor 1. You.

At the time of position control, the controller 21 sets the switch control signal SW to “0”. At this time, the switch 27 selects the output signal of the actuator position error detection circuit 7,
Since this output signal is used as the reference speed signal, the gain switch
Control is performed so that the 19 output signal matches the output signal of the actuator position error detection circuit 7.

At the time of speed control, the controller 21 sets the switch control signal SW to “1”. At this time, switch
27 selects the output signal of the position error detection circuit 25, so that this output signal is used as the reference speed signal, and control is performed so that the output signal of the gain switch 19 matches the output signal of the position error detection circuit 25. .

Next, the operation of this embodiment will be described in detail with reference to FIG.

(1) Operation During Position Control The controller 21 sets the switch control signal SW to “0” during position control. Therefore, the transistor 27a is turned off, the switch 27b is turned on, and the tracking actuator position error signal ES and the signals H1V and H2V are input to the operational amplifier 91 via the switch 27b.
The switch 89, the transistor 61a, and the transistor 61b are off.

 Here, if R83a = R83b << R87, in this case, control is performed such that ES / R121 ≒ − (H1V + H2V) / 2R87.

When the tracking actuator position error signal ES is generated, the motor 1 rotates. The rotation direction is set so that the signal ES becomes smaller. Therefore, the pickup 3 is controlled so that the signal ES always becomes "0", and so-called feed servo is performed.

At this time, since the switch control signal SW is “0”, the transistors 61a and 61b are off.

Therefore, the differential constants of the differentiators 13a and 13b are respectively
The signals become C55a / R59a and C55b / R59b, and a signal having a relatively large gain is sent to the rectifiers 15a and 15b.

At this time, since the switch 89 is open, the resistance value of the gain switch 19 is R87.

(2) Operation at the Time of Speed Control At the time of speed control, the controller 21 determines whether the destination point to which the pickup 3 should be moved is forward or backward as viewed from the current position of the pickup 3 and determines the movement direction.

In the positive direction, for example, the F / R signal is set to “1”, and the transistor 109 is turned on. At this time, assuming that the resistance 111 and the resistance 115 are equal, the operational amplifier 107 functions as an inverting amplifier with a gain of “−1” and sends a signal obtained by inverting the output signal of the operational amplifier 103 to the operational amplifier 91 via the transistor 27a. .

In the reverse direction, the controller 21 sets the F / R signal to "0" and turns off the transistor 109. At this time, the operational amplifier 107 functions as a non-inverting amplifier having a gain of “1”, and sends an output signal of the operational amplifier 103 to the operational amplifier 91.

Next, the controller 21 sets data corresponding to the distance in the terminals D0 to D7. Then, the signal LOAD is set to “0”, and the data set in the terminals D0 to D7 is
Preset to a and 23b.

Next, the signal LOAD is returned to “0” to start counting, and the switch control signal SW is set to “1”. Therefore, the transistor 27a is turned on, the switch 27b is turned off, the transistors 61a and 61b are turned on, and the switch 89 is turned on.

At this time, the output signal VE of the position error detection circuit 25a and the output signals H2V and H1V of the rectifiers 15a and 15b are input to the operational amplifier 91, and VE / R99 {-(H1V + H2V). (R87 + R88)} (2. R87 / R88).

The signals H2V and H1V are almost equal to 0 because they are initially rotating at very low speed.

Therefore, the motor 1 is fully accelerated in a predetermined direction.

When the motor 1 rotates, position signals H1S and H2S are generated,
As shown in FIG. 7, the count values of the counters 23a and 23b decrease, and the magnitude of the signal VE also decreases.

Therefore, the reference speed voltage of the motor 1 also decreases, and the rotation speed becomes the smallest when the values of the counters 23a and 23b are "1".

FIG. 8 shows the waveforms of the signals of the respective parts at this time.

When the pickup 3 reaches the target position, the counter 23
The count values of a and 23b become "0" and the counters 23a and 23b
Are both "1", the signal 1 is sent to the STOP terminal via the AND gate 101.

When the STOP signal becomes "1", the controller 21 sets the switch control signal SW to "0" and returns to the above-described position control state.

When the switch control signal SW is "1", the transistors 61a and 61b and the switch 89 are on.

 The differential constant of the differentiator 13a is C55a / R57a / R59a / (R57a + R59a), and the differential constant of the differentiator 13b is C55b / R57b / R59b / (R57b + R59b).

 The resistance value of the gain switch 19 is R87 · R89 / (R87 + R89).

As described above, the differential constants of the differentiators 13a and 13b are smaller than those during the position control, so that the gains of the operational amplifiers 53a and 53b are smaller than those during the position control.

On the other hand, since the resistance value of the gain switch 19 is smaller than that during the position control, the gain of the gain switch 19 is larger than that during the position control.

Thus, at the time of position control, the gain switches 11a, 1
When the gain of 1b is increased, the gain is reduced by the gain switch 19, and the gain switches 11a and 11a are controlled during speed control.
When the gain of 1b is reduced, the gain is increased by the gain switch 19, and control is performed so that a predetermined voltage is applied to the motor 1.

The signals H1D and H2D can be kept within the dynamic ranges of the operational amplifiers 53a and 53b and the operational amplifiers 71a and 71b of the rectifiers 15a and 15b.

Also, during the tracking servo (at the time of position control), that is, when the pickup 3 moves at an extremely low speed, the signal H1
D, the signal H2D, the operational amplifiers 53a, 53b and the rectifiers 15a, 1
It can be made much larger than the minimum limit value of the offset voltage of the operational amplifiers 71a and 71b of 5b.

For this reason, by generating an appropriate speed voltage during speed control (during high-speed movement) and during position control (during low-speed movement), it is possible to stably send the pickup with high performance.

Note that the present invention can be variously modified within the scope of the technical idea.

For example, in this embodiment, the speed detection is performed by the position detectors 9a and 9b.
However, a so-called moving magnet type speed detector of a magnet and a coil type may be separately provided.

Further, a magnetic, optical or electrostatic position detector may be used.

Various motors such as a linear motor, an electrostatic motor, a brushless motor, and a stepping motor can be used as the motor 1.

The position detectors 9a and 9b are of a two-phase type, but may be of a polyphase type.

Further, the position of the pickup at the time of a track jump is detected by pulse counting, but a speed integration method or a potentiometer method may be used.

[Effects of the Invention] As described above in detail, according to the present invention, an appropriate speed voltage is generated during speed control (during high-speed movement) and during position control (during low-speed movement), thereby achieving stable operation. And a disk reproducing device capable of sending a pickup with high performance.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of a disk reproducing apparatus using a feed servo circuit according to one embodiment of the present invention, FIG. 2 is a schematic diagram showing the vicinity of a pickup, and FIGS. FIG. 5 is a circuit diagram showing a configuration of a pickup feed servo circuit, FIG. 6 is a waveform diagram of each signal in FIG. 5, and FIG. 7 is a signal H1S, STOP, VE.
FIG. 8 is a waveform diagram of signals STOP, H2V, H1V, and VE. 1 ... Motor 3 ... Pickup 9a, 9b ... Position detector 11a, 11b ... Gain switch 13a, 13b ... Differentiator 15a, 15b ... Rectifier 17 ... Addition unit 19 ... Gain switch 21 ... ... Controller 23 ... Counter 25 ... Position error detection circuit 27 ... Switch 29 ... Comparator 31 ... Power amplifier

Claims (3)

(57) [Claims] 1. A disk reproducing apparatus having a pickup feed servo circuit for reading information recorded on a disk via a pickup, comprising: a driving unit for driving the pickup in a radial direction of the disk; Speed detecting means for detecting a moving speed of the pickup and outputting a speed signal corresponding to the moving speed, a rectifying circuit including at least an operational amplifier for rectifying the speed signal output by the speed detecting means, A plurality of gain switching circuits respectively disposed before and after the rectifier circuit; and mode switching means for switching between a first control mode for track jump of the pickup and a second control mode for tracking servo. The speed signal output from the gain switching circuit at the subsequent stage of the rectifier circuit. And a reference speed signal corresponding to the control mode selected by the mode switching means, a means for feeding back the difference signal to the driving means, and a speed signal supplied to the operational amplifier of the rectifier circuit, In the first control mode, it is selected by the mode switching means so as to be within the dynamic range of the operational amplifier and to satisfy the minimum limit value of the offset voltage of the operational amplifier in the tracking servo in the second control mode. Control means for changing the gains of the gain switching circuits before and after the rectifier circuit according to the control mode. 2. The apparatus according to claim 1, wherein said speed detecting means includes means for detecting a position signal of said pickup, and means for differentiating said detected position signal to continuously obtain a speed signal. 2. The disc reproducing apparatus according to claim 1. 3. The brushless motor according to claim 1, wherein the driving means includes a brushless motor, the speed detecting means detects a position signal of the brushless motor, and a speed is obtained by differentiating the position signal detected by the position detecting means. 2. The disc reproducing apparatus according to claim 1, further comprising: means for outputting a signal.