JPH08186996A - Drive circuit for composite motor - Google Patents

Abstract

PURPOSE: To drive a motor so as to obtain a strong motor torque simultaneously with preventing backlash, in the case of driving the composite motor which is provided with a plurality of DC motors connected to one another to drive a driven object by simultaneously rotating these DC motors. CONSTITUTION: This drive circuit is constituted so that the motor can be set to be first drive condition with different voltage applied to each DC motor 20, 30 and to the second drive condition with almost equal voltage applied to each of these DC motors in accordance with use conditions of a composite motor 1.

Description

Detailed Description of the Invention [Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit for a composite type motor which has a plurality of DC motors connected to each other and which drives the driven body by the simultaneous rotation of these DC motors.

[0002]

2. Description of the Related Art The applicant of the present application, as Japanese Patent Application No. 6-212842 on August 12, 1994, provides a plurality of DC motors and connects the rotating shafts of these DC motors. It has been proposed that a plurality of DC motors cooperate to drive, for example, a turntable for a composite type motor.

The rotary shaft of such a composite motor is connected to each other by a connecting member such as a gear or a timing belt, but smooth rotation is prevented from being hindered by backlash of the connecting member. For this reason, this drive circuit is designed so that the drive voltage applied to each of the plurality of DC motors is different.

[0004]

For example, the voltage applied to the spindle motor that rotationally drives the disk of the compact disk player slightly changes in level during negative feedback control such as CLV control. In the case of using the above-mentioned composite type motor under such conditions, in order to reduce the backlash caused by the variation of the rotating state of both DC motors to the practical range, the DC motors are set to the predetermined ranges. It has been experimentally found that it is required to apply a driving voltage having a voltage difference of 1 or to make a high impedance state between the terminals of one of the DC motors. However, since strong torque is not required in the steady state, there is no particular problem even in such an unbalanced voltage application state.

On the other hand, when the CD player performs a search from the outermost recording area to the innermost recording area of the disc, the number of rotations of the spindle motor is correspondingly increased by about 2.3 times. It is necessary to raise the speed and, in the opposite case, to 1 / 2.3 times, but in order to achieve this in a short time, a strong motor torque is required.

During such rapid acceleration / deceleration of the spindle motor, a high voltage is usually applied between the terminals of the motor. At this time, in the drive circuit of the composite motor described above, one of the motors is driven. Since a voltage lower than that is always applied to the other motor with respect to the motor, the desired motor torque cannot be obtained, resulting in a very inefficient use state.

[0007]

[Means for Solving the Problems] In order to drive a driven body,
A driving circuit for driving a composite type motor comprising a plurality of motors and a connecting means for connecting respective rotating shafts of the plurality of motors, wherein an application for applying to the plurality of motors. It can be driven in a first drive state in which the voltages are different and in a second drive state in which the applied voltages applied to the plurality of motors are substantially the same.

[0008]

When the voltage applied to the DC motor is finely changed and a very strong motor torque is not required, it is in the first driving state, and when a strong motor torque is required, it is in the second driving state. By driving with, backlash can be suppressed and strong motor torque can be withdrawn if necessary.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a composite type motor driven by the circuit of the present invention will be described below. FIG. 1 is a development view showing each component of the composite type motor 1, and FIG. 2 is a perspective view of the composite type motor 1. By attaching the mounting screws 2 and 3 through the holes 5 and 6 formed in the motor chassis 4 and screwing them into the mounting holes 7 and 8 of the first and second DC motors 20 and 30, respectively. DC motors 20 and 30 are fixed to the motor chassis 4.

Here, the DC motors 20 and 30 are the same general-purpose motors that can be used independently and have the same outer diameter and characteristics. The motor chassis 4 is provided with mounting holes 13 and 14 for fixing the composite motor 1 to a required device.

Gears 22 and 32 having the same diameter are mounted on the rotary shafts 21 and 31 of the motors 20 and 30 which are parallel to each other, and the gears 22 and 32 have teeth 9 formed on the inner peripheral side thereof. Are connected by a timing belt 10.
Therefore, the DC motors 20 and 30 have a rotation speed ratio of 1
They are connected in pairs.

The rotating shaft 21 of the first DC motor 20 is longer than the rotating shaft 31 of the second DC motor 30, and penetrates the hole 12 formed in the top cover 11. It extends to the outside and is used as a rotary output shaft of the composite motor 1. Therefore, the rotary output of the composite motor 1 is taken out as a combined output of the rotary outputs of the DC motors 20 and 30. Further, the top cover 11 is provided with the claws 15 and 15, and the holes 1 formed in the motor chassis 4 are formed.
By being engaged with the gears 6 and 16, the gears 22 and 32 and the timing belt 10 are covered and dust and dirt are prevented from adhering.

A second embodiment of the composite type motor driven by the circuit of the present invention will be described below with reference to FIG. 3 which is a perspective view thereof. In the above-mentioned first embodiment, the DC motor 2
Although 0 and 30 are connected by the timing belt 10, in the second embodiment, both motors are connected by gears. The composite motor 40 of the second embodiment is a direct current motor. Spur gears 52 and 62 are attached to rotary shafts 51 and 61 of 50 and 60, and these spur gears 52 and 62 are connected by a connecting gear 42 which is axially supported by a motor chassis 41. Therefore, the rotary output of the composite type motor 40 is taken out from the rotary shaft 51 of the DC motor 50 as a combined output of the rotary outputs of the DC motors 50 and 60.

Below, the above-mentioned composite motors 1 and 40 are
A disk drive in a CD-ROM drive device is mounted on a base mechanism 80 for rotating and reproducing information stored on the disk, and is a drive for driving a spindle motor and an optical pickup for rotating the disk. The case of application as a motor will be described.

FIG. 4 is a perspective view showing the base mechanism 80. A turntable 82 for supporting a disc (not shown) has a circular cone shape which is engaged with the center hole of the disc. Convex portion 83 and circular mounting surface 84 on which a disk is mounted
Consists of This turntable 82 is a chassis 81.
The motor chassis 4 is fixed to one surface of the one side, and is fixed to the rotary output shaft 21 of the composite type motor 1 described in the first embodiment.

Two guide shafts 85 and 86 extending in parallel are fixedly arranged on the other surface of the chassis 81, and an optical pickup 88 having an objective lens 87 is movable along the guide shafts 85 and 86. It is supported. A rack 89 extending parallel to the moving direction of the optical pickup 88 is fixed to the optical pickup 88, and the rack 89 is mounted on a small-diameter first reduction gear 90 pivotally supported on the other surface of the chassis 81. It is in mesh.

The large-diameter second reduction gear 91 is integrally formed coaxially with the first reduction gear 90, and the second reduction gear 91 is rotatably supported on the other surface of the chassis 81. The third reduction gear 92 having a small diameter is meshed. The large-diameter fourth reduction gear 93 is integrally formed coaxially with the third reduction gear 92, and the fourth reduction gear 93 is a shear gear.
It meshes with a small-diameter gear 94 fixed to the rotary output shaft 51 of the composite motor 40 described in the second embodiment, which is fixed to one surface of the shaft 81.

A fifth embodiment of the drive circuit for rotating the composite type motors 1 and 40 will be described below.
This will be described with reference to the drawings. The same reference numerals are given to constituent elements common to the description of FIGS. 1 to 4 described above.

The optical pickup 88 holds an objective lens 87 at a position facing a recording surface of a CD-ROM disc (hereinafter simply referred to as a disc) 100 formed according to a CD format, and further holds this objective lens 87. Although having an actuator portion for driving in the direction perpendicular to the recording surface and in the radial direction, only the tracking coil 104 for driving in the radial direction is shown in the drawing.

That is, when a current flows through the tracking coil 104, the objective lens 87 moves in the radial direction of the disk against the biasing force toward the center, depending on the direction of the current flow. It is configured to balance at the center position by force.

The optical pickup 88 irradiates the recording surface of the disk 100 with laser-focused light through the objective lens 87, and detects the reflected light by a detector disposed inside, and detects this as an electric signal. The detection signal S1 converted to is output. The detection signal S1 is supplied to the RF amplifier 11
The signal is input to the signal processing circuit 116 via the signal line 5 and a tracking error detection circuit (hereinafter referred to as TE detection circuit) 1
Enter 01. The signal processing circuit 116 EFM demodulates the input signal according to the CD format and further CIR.
The error is corrected by C and the data is output.
The sub-code signal S2 and the frame sync signal S3 are detected and output.

The TE detection circuit 101 detects a tracking error signal (hereinafter referred to as TE signal) S4 by a known method based on the input signal, and detects this signal from the phase compensation circuit 10
2. Tracking coil 104 via drive circuit 103
Apply to. At this time, the applied voltage signal S5 applied to the tracking coil 104 by the drive circuit 103 is connected to one input terminal of the switch 106 via the low-pass filter 105.

The tracking control circuit 112 is a sub controller.
The search signal S2 and the search command signal S6 output from the search command circuit 128 based on the operation by the operator are input, and the feed signal S7 is switched to the switch signal 10 in the manner described later.
The switch switching signal S8 is applied to the switching signal input terminals of the switch 106 and the switch 111 while being output to the other input terminal of the switch 6.

The movable terminal of the switch 106 is connected via a motor drive circuit 109 to the voltage application terminal of one of the DC motors 50 of the composite type motor 40 for feeding described above. It is connected to the voltage application terminal of the other DC motor 60 of the composite type motor 40 via the voltage dividing resistor 107 and the motor drive circuit 110. The other application terminal of each DC motor is connected to the ground.

The input section of the motor drive circuit 110 is
It is connected to the fixed terminal of the switch 111 via the voltage dividing resistor 108, and the movable terminal of this switch is connected to the ground. As described above, these DC motors 50, 60
The rotation detector 114 similarly generates a predetermined number of revolutions per one rotation of the composite type motor 40 by the cooperation of the DC motors and the rotating body 113 connected to the shaft. The detection pulse signal S9 including the pulse to be output is output to the tracking control circuit 112.

The amount of movement of the optical pickup 88 per pulse of the detection pulse signal S9 is predetermined, and the tracking control circuit 112 counts the number of pulses as necessary to move the optical pickup 88. You can check the quantity.

The phase comparator 118 compares the phase of the frame synchronizing signal S3 recorded at a predetermined interval on the disk track with respect to the reference signal S10 of a predetermined frequency output from the internal oscillator 117, and determines whether the phase synchronization signal S3 is advanced or delayed. The determination signal S11 that changes between low and high binary levels according to each state is
It outputs to one fixed input terminal of the switch 120 via the pass filter 119.

The spindle motor control circuit 127 inputs the sub-code signal S2 and the search command signal S14 output from the search command circuit 128, and sends the spindle signal S12 to the switch 120 by the procedure described later. The switch switching signal S13 is applied to the switching signal input terminals of the switch 120 and the switch 128 while being output to the other fixed input terminal.

The movable terminal of the switch 120 is a composite type motor for the spindle described above via a motor drive circuit 123.
It is connected to the voltage application terminal of one of the DC motors 20 of the motor 1 and is connected to the other DC motor 30 of the composite type motor 1 through the voltage dividing resistor 121 and the motor drive circuit 124. It is connected to the voltage application terminal. The other application terminal of each DC motor is connected to the ground. The gain of the spindle motor drive circuits 123 and 124 is 1
Be set to

The input portion of the spindle motor drive circuit 124 is connected to the fixed terminal of the switch 128 via the voltage dividing resistor 122, and the movable terminal of this switch is connected to the ground. As described above, the DC motors 20 and 30 are axially connected, but the rotation detector 126
Is a rotary body 1 that is also axially connected to these DC motors.
In cooperation with 25, a detection pulse signal S15 including a predetermined number of pulses generated per one rotation of the composite motor 1 is output to the spindle motor control circuit 127.

The operation of the above configuration will be described. It should be noted that the focus servo is assumed to be operating in a normal state as necessary, and a description thereof will be omitted. When normal signal reproduction is performed, the tracking control circuit 112 controls the control signal S so that each movable terminal of the switches 106 and 111 maintains the position shown in FIG.
8 is output. At this time, the tracking coil 104 has a T
A voltage varying according to the E signal S4 is applied, and the DC component of the applied voltage signal S5 is further applied to the composite type mode for the field.
Is applied to the data 40.

By constructing each of these systems as negative feedback, the objective lens 87 quickly moves from its center position in the direction in which the tracking shift is reduced, and the optical pickup 88 is centered on the objective lens 87. A relatively slow moving tracking control is performed by the composite motor 40 for feeding so as to come to the position. At this time, the voltage applied to the DC motor 60 of the composite type motor 40 is applied to the DC motor 5 by the voltage dividing resistors 107 and 108.
It is suppressed to about 30% with respect to the voltage applied to 0.

On the other hand, during this signal reproduction, the spindle motor control circuit 127 outputs the control signal S13 so that the movable terminals of the switches 120 and 128 maintain the positions shown in FIG. Then, a voltage based on the comparison between the reference signal S10 and the frame synchronization signal S3 is applied to the composite motor 1 for the spindle,
General PLL for CLV control with constant linear velocity
Control is performed.

The loop of this PLL is based on the reference signal S1.
It is assumed that not only the phase difference control between 0 and the frame synchronization signal S3 but also the frequency difference is pulled in. At this time, the voltage applied to the DC motor 30 of the composite motor 1 is suppressed to about 30% of the voltage applied to the DC motor 20 by the voltage dividing resistors 121 and 122. There is.

As described above, tracking control and CL
At the time of normal signal reproduction by V control, the motors 60 and 30 of the composite type motors 1 and 40 respectively apply only about 30% of the voltage to the motors 50 and 20 paired therewith. Therefore, the backlash of the composite motor during the negative feedback control as described above can be suppressed.

At the time of reproducing the signal, the tracking control circuit 112 and the spindle motor control circuit 127 respectively input the subcode signal S2 from the signal processing circuit 116, and from this information, the current reproduction position on the disc. It can be confirmed as an absolute reproduction time from the recording start position near the innermost track.

Next, the search command circuit 128 sends information about the destination to the search command signal S based on the input by the operator.
6 and S14, when the tracking control circuit 112 receives the search command signal S6, the difference between the current reproduction position and the target position of the moving destination is first converted into time and laser light irradiation is performed. Find the distance traveled by a point.

In order to execute this movement, first, the switches 106 and 111 are switched by the switch control signal S8.
5 shifts from the state shown in FIG. 5 to the other state, the switch 106 cancels the negative feedback of the tracking control to select the feed signal S7, and the switch 111 is opened to feed the signal. The pair of DC motors 50 and 60 of the composite type motor 40 are controlled so that the same drive voltage is applied.

At the same time, the voltage of the feed signal S7 is set to a voltage value of a predetermined level having a polarity set according to the moving direction to drive the composite motor 40 for feeding, and the optical pickup 88 is driven. Start moving. The amount of movement of the optical pickup 88 at this time is detected by counting the number of pulses of the detection pulse signal S9. After that, for example, when the movement is completed up to 80% of the desired movement distance, the feed for braking is obtained. The voltage polarity of the signal S7 is reversed for a predetermined time. After that, each connection of the switches 106 and 111 becomes the state of FIG. 5 again, and the switch control signal S8 is set so that the tracking control is restarted.

By the above operation, the irradiation point is brought near the target position, but finally, the tracking control is restarted and the subcode signal S2 is read out.
When the current reproduction position is confirmed, a minute movement such as a one-track jump is further performed to reach the target position, but the detailed description of these operations will be omitted.

When performing this search, the rotation speed of the composite motor 1 for the spindle is changed at the same time as the movement of the irradiation point so that the CLV control at the movement destination is quickly locked. The control is performed so that the optimum rotation state is achieved for the CLV control.

Therefore, the spindle motor control circuit 12
When 7 receives this search command signal S14, the absolute time ahead of the search is confirmed and the optimum rotation speed .omega.m required for CLV control there is calculated. Then, the detection pulse signal S15
In accordance with the comparison with the current rotation speed ωr of the composite motor 1 which is confirmed by monitoring, the speed of the spindle signal S12 is set to a predetermined voltage value in order to accelerate and decelerate in the direction in which they approach each other in a short time. Set to Vh.

Simultaneously with this setting, the switch control signal S1
3 shows the connection states of the switches 120 and 128 as shown in FIG.
State to the other state, switch 120 is CL
The negative feedback of the V control is canceled to select the spindle signal S12, and the switch 128 is opened to apply the same drive voltage to the pair of DC motors 20 and 30 of the composite motor 1 for spindle. To control.

Here, when the search is performed from the reproduction position A on the outer peripheral side of the disc to the reproduction position B on the inner peripheral side, the relationship between the optimum rotation speed ωm at the reproduction position B and the current rotation speed ωr is Since ωm> ωr, the composite motor 1 is applied with the voltage value Vh of the spindle signal S12 set for acceleration in a short time. Then, for example, when the rotation speed Vr is accelerated to the optimum rotation speed Vm, the switch 1 is again activated.
The switch control signal S13 is controlled so that 20,128 become the state shown in FIG. 5 and the CLV control is restarted.

On the contrary, when the search is performed from the reproduction position on the inner circumference side to the reproduction position on the outer circumference side of the disk, the polarity of the voltage value Vh of the spindle signal S12 is reversed and the rotation speed is increased. It is needless to say that the CLV control is similarly restarted.

As described above, at the time of search, each composite type mode is used.
In order to extract a high motor torque from the motors 1 and 40, a higher voltage is applied than in normal reproduction and the same voltage is applied to each pair of DC motors.

FIG. 6 shows a second embodiment of the circuit of the present invention, in which the circuit in the frame 202 is applied to the frame 201 portion of the drive circuit in FIG. In this case, the movable terminal of the switch 120 is directly connected to each input portion of the drive circuits 135 and 136, and the movable terminal of the switch 138 connected to one voltage application terminal of the DC motor 30 of the composite type motor 1. Is connected to either one of the fixed terminal connected to the output part of the drive circuit 136 and the fixed terminal connected to the ground via the resistor 137, depending on the state of the switch control signal S13.

In such a configuration, since the movable terminal of the switch 138 selects the position shown in the figure during the CLV control, the resistor 137 is interposed between both voltage application terminals of the DC motor 30 at this time. The same voltage is applied to both DC motors because the movable terminal of the switch 138 is connected to the output part of the drive circuit 136 during the search.

Therefore, during the CLV control, the DC motor 3
A current flows through the resistor 137 through the resistor 137 due to an internal electromotive force, thereby generating torque in a direction to brake the rotation of the composite motor 1, and the braking torque suppresses backlash. The braking torque generated at this time can be adjusted by the value of the resistor 137, and the value is appropriately selected in the range of 0 to ∞ based on the design condition and the result of the experiment.

The value ∞ of the resistor 137 means that both terminals of the motor are opened, and at this time, the motor 30 is operated only by the inertial moment of the motor. However, it has been confirmed by experiments that the backlash that occurs at this time may be reduced to a range where there is no practical problem.

FIG. 7 shows a third embodiment of the circuit of the present invention, in which the circuit within the frame 203 is applied to the frame 201 portion of the drive circuit of FIG. In this case, the output portion of the drive circuit 132 is the resistor 1
It is connected to one of the voltage application terminals of the DC motor 30 of the composite type motor 1 via 34, and the switch 133 is configured to short-circuit this resistor 134 according to the state of the switch control signal S13. ing.

In such a configuration, since the switch 133 selects the position shown in the figure during the CLV control, the voltage application terminal of the DC motor 30 at this time is connected to the drive circuit 132 via the resistor 133. The output voltage is applied, and at the time of the search, the same voltage is applied to both DC motors because the resistance is short-circuited.

Therefore, during CLV control, the DC motor 3
Since the current flowing to zero is reduced, the rotational torque generated in the DC motor 20 is suppressed, and in some cases, the same effect as reducing the voltage applied to the DC motor of the first embodiment is obtained. The obtained backlash can be suppressed.

Although the circuits shown in FIG. 6 or 7 are adopted in place of the circuit in the frame 201 of FIG. 5 in the second and third embodiments, the present invention is not limited to this. Frame 2 of 5
These circuits may be adopted instead of the 00 part. Further, in the above embodiment, the composite type motor is composed of two DC motors, but the number of DC motors may be increased if necessary.

Further, in the first embodiment, the voltage applied to the DC motor 30 or 60 is lowered as necessary by the voltage dividing resistor, but the present invention is not limited to this, and the motor driving is possible. The motor drive circuit 110 for the circuits 109 and 123,
You may comprise so that the gain of 124 may be reduced as needed.

Further, in the above embodiment, the first embodiment of the composite type motor using the timing belt as the connecting means is used as the spindle motor, and the second embodiment using the gear is for the feeding. Although it is used as a motor, it is not limited to this, and the reverse use is also possible, and it goes without saying that both types may employ the same type of composite motor.

In the second embodiment of the composite motor, the rotation output is taken out from the rotary shaft of the DC motor 50, but it is taken out from the rotary shaft of the connecting gear 42. Good. Further, in the above embodiment, the case where the composite type motor and the circuit of the present application are adopted in the CD-ROM drive device is shown, but the present invention is not limited to this, and various modes are conceivable. is there.

[0058]

According to the circuit of the present invention, when a composite motor is driven by, for example, negative feedback control in which a very strong torque is not required and the applied voltage constantly fluctuates, the interior of the composite motor is reduced. In order to suppress the backlash by changing the driving state of each DC motor, the substantially same voltage is applied to each motor when a strong torque is to be drawn from this composite type motor. Therefore, the advantages of the composite type motor can be maximized and the weak points thereof can be covered.

[Brief description of drawings]

FIG. 1 is a development view showing respective constituent parts in a first embodiment of a composite motor.

2 is a perspective view of the composite motor shown in FIG.

FIG. 3 is a perspective view of a second embodiment of a composite type motor.

FIG. 4 is a perspective view of a base mechanism in the CD-ROM drive device.

FIG. 5 is a block diagram of a driving circuit of a composite type motor according to the first embodiment of the present invention.

FIG. 6 is a partial drive circuit diagram showing a second embodiment of the present invention.

FIG. 7 is a partial drive circuit diagram showing a third embodiment of the present invention.

[Explanation of symbols]

 1 composite type motor 10 timing belt 20 direct current motor 30 direct current motor 40 composite type motor 50 direct current motor 60 direct current motor 82 turntable 88 optical pickup 100 CD-ROM disc 101 Tracking error detection circuit 105 Low-pass filter 112 Tracking control circuit 116 Signal processing circuit 117 Internal oscillator 118 Phase comparator 127 Spindle motor control circuit

Claims (5)

[Claims] 1. A drive circuit for driving a composite type motor comprising a plurality of motors and a connecting means for connecting respective rotating shafts of the plurality of motors to drive a driven body. Yes, a composite type motor that can be driven in a first drive state in which the applied voltages applied to the plurality of motors are different and a second drive state in which the applied voltages applied to the plurality of motors are substantially the same. -A drive circuit for the data. 2. A drive circuit for driving a composite motor, comprising: a plurality of motors and a connecting means for connecting the respective rotary shafts of the plurality of motors to drive a driven body. And a state switching for switching the driving state between a first driving state in which the applied voltages applied to the plurality of motors are different and a second driving state in which the applied voltages applied to the plurality of motors are substantially the same. A driving circuit of a composite motor having a means. 3. The drive circuit for a composite motor according to claim 1, wherein the connecting means is a gear. 4. The drive circuit for a composite motor according to claim 1, wherein the connecting means is a timing belt. 5. The driven body is a disc on which information is recorded, and when reproducing the information recorded on the disc, the plurality of motors are set to the first drive state,
Further, the first drive state is set to the second drive state when the rotational speed of the disk is changed rapidly.
A driving circuit for a composite type motor according to the above paragraph.