JPH06275009A - Moving body reciprocating driving device - Google Patents

Abstract

PURPOSE:To reduce the size of a power supply and to reduce the cost of the device by smoothing the power supply current being supplied to a motor and reducing a maximum current. CONSTITUTION:When a voice coil type linear motor is to be driven from a shuttle stop condition, an acceleration current 'ie' is supplied to a linear motor coil 6 by the drive of motor drivers 4 and 5 and the shuttle is accelerated to a target speed. At that time, the current 'ie' becomes a current is of a power supply 1 and a discharge current 'ic' of a sum of current 'is' of a power supply 1 and a discharge current 'ic' of a capacitor 3 and this sum is supplied to the coil 6. When the speed reaches the target speed, the shuttle moves by its inertia and a small amount of the current 'ie' is supplied. Therefore, the current 'ie' is small during a constant speed motion, the capacitor 3 is charged by the current 'is' and a driving voltage Ve approaches to a power supply voltage Vs. While the shuttle speed 'is' being reduced, the speed reduction current 'ie' is supplied to the coil 6 from the capacitor 3, the capacitor 3 is discharged and the voltage Ve is reduced. When the shuttle is stopped, the current 'ie' becomes zero, the voltage of the capacitor 3 becomes the voltage Vs and the current 'is' becomes a small value of the bias current of the circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving body reciprocating drive device for linearly reciprocating a moving body using a motor such as a voice coil type linear motor as a drive source, and more particularly to card-like recording in an optical information recording / reproducing apparatus. The present invention relates to a movable body reciprocating drive device suitable for reciprocating drive of a medium or an optical head.

[0002]

2. Description of the Related Art Conventionally, various types of information recording media such as discs, cards, tapes, etc. are known as a form of an information recording medium for optically recording information or optically reading the recorded information. ing. Some of these optical information recording media are recordable and reproducible, and only reproducible. In particular, a card-shaped recording medium (hereinafter referred to as an optical card) as a recording medium is expected to be widely used in the future because of its features such as ease of manufacturing, portability, and accessibility. Various types of optical information recording / reproducing devices for the optical card are provided.

In such an optical information recording / reproducing apparatus, recording / reproducing is performed while always performing auto-tracking and auto-focusing control. When information is recorded on a recording medium, information is recorded as an optically detectable information pit string by scanning an information track with a light beam that is modulated according to the recording information and focused on a minute light spot. It On the other hand, when reproducing information from the recording medium, a light beam spot with a constant power that does not record on the recording medium scans the information pit row of the information track, and the reflected light or transmission from the recording medium at this time is transmitted. The light is detected and the recorded information is reproduced based on the detection signal.

FIG. 9 is a diagram showing the configuration of a typical optical system of a conventional optical information recording / reproducing apparatus. In the figure, 101 is a semiconductor laser provided as a recording / reproducing light source. The luminous flux of the semiconductor laser 101 is collimator lens 1
After being collimated by 02, it is divided into a plurality of light beams by the diffraction grating 103. Then, the plurality of light beams pass through the polarization beam splitter 104 and the quarter-wave plate 105, respectively, and are further condensed by the objective lens 106 to be collected by the optical card 1.
It is imaged as a minute light spot on 07. Optical card 1
The reflected light from 07 again passes through the objective lens 106 and the quarter-wave plate 105 and enters the polarization beam splitter 104, where it is reflected by the toric lens 108 and enters the photodetector 109. The photodetector 109 detects the reflected lights of the plurality of light beams, and at this time, the diffraction grating 10
Recording, reproduction, and autofocusing control based on the detection signal of the 0th-order diffracted light among the light beams divided by 3 (hereinafter referred to as A
(Referred to as F) is performed. Further, auto-tracking control (hereinafter referred to as AT) is performed based on the detection signal of the ± 1st-order diffracted light. Here, the astigmatism method is used for AF and the three-beam method is used for AT.

FIG. 10A is a schematic plan view of a general optical card. A number of information tracks are arranged in parallel on the optical card 107, and some of them are shown as T1, T2, and T3. This track is a tracking track tt
An information track is provided between each tracking track. The tracking tracks tt1 to tt4 are formed of a material having a reflectance different from that of the grooves or the tracks T1 to T3, and are separated from the information tracks by such a difference in reflectance. The tracking track is used as a guide for obtaining the tracking signal. In FIG. 10A, the track T3 is irradiated with 0th-order diffracted light 110 for recording, reproduction, and AF, and the tracking tracks tt3 and tt4 are irradiated with AT ± first-order diffracted lights 111 and 112, respectively. The diffracted light 1
Tracking signals, which will be described later, are generated by the reflected lights from 11, 112, and the 0th-order diffracted light 110 is correctly recorded on the track T.
Tracking control is performed so as to scan the upper part. As a result, the diffracted lights 110, 111, 112 are scanned in the left-right direction in the drawing on the optical card 107 by a mechanism described later while maintaining the same positional relationship.

By the way, there are two types of scanning methods, one is to move the optical system and the other is to move the optical card. In either case, the optical system and the optical card reciprocate relative to each other. A part where the speed is not constant occurs at both ends. This state is shown in FIG. The horizontal axis of FIG. 10B represents the horizontal direction of the optical card, and the vertical axis represents the scanning speed. Normally, the constant speed scanning area at the center of the optical card 107 is used as a recording area.

Next, a mechanism for scanning the light spot by moving the optical card will be described. FIG. 11 is a perspective view showing an example of the scanning mechanism, and 120 is a shuttle for mounting the optical card 107. Shuttle 120 is optical head 12
The shuttle 120 is supported by moving coils 122a and 122b that are connected to substantially the center of both sides of the shuttle 120 as a driving unit for reciprocating relative to the shuttle 1. Center yokes 123a and 123b are inserted into the moving coils 122a and 122b, and the moving coils 122a and 122b are permanent magnets 124a and 124b.
A gap that is slidable with respect to the center yoke 123 is retained.
The a and 123b are fixed to the lower yokes 125a and 125b at both sides not shown. Then, the moving coils 122a and 122b, the center yokes 123a and 1
23b, permanent magnets 124a and 124b, and a yoke 125.
The boil coil type linear motor section is constituted by a and 125b.

At the center of gravity of the shuttle 120, the optical card 1
A guide shaft 126 for guiding the sliding of 07 in the track direction is inserted, and bearings 127a, 127b via springs are urged against the upper surfaces of the center yokes 123a, 123b from the protruding portion on the upper portion of the shuttle 120, respectively.
Both ends of the guide shaft 126 are fixed to blocks 129a and 129b fixed to the main body frame. Further, both ends of the linear encoder 132 that controls the drive speed are attached to the blocks 129a and 129b in parallel with the guide shaft 126, and the encoder detector 133 is attached to the shuttle 120. Also, the shuttle 120
A light blocking plate 134 for determining the reverse position of the light shielding plate 134 is formed integrally with the shuttle 120, and the blocks 129a and 129b on both sides are provided with a reverse position detector 135 for detecting the light blocking plate 134.
a and 135b are provided.

In the above structure, the linear encoder 1
The shuttle 120, which is controlled at a constant speed by the encoder 32 and the encoder detector 133, has a guide shaft 126 slidably supported at its center of gravity and bearings 127a, 127b arranged to maintain the center of gravity balance. Move along. At this time, recording or reproduction is performed on the optical card 107 by the optical head 121 that can move in a direction orthogonal to the track direction of the optical card 107 by a mechanism (not shown). When the shuttle 120 moves to the reversal area of the optical card 107, it is detected that the light blocking plate 134 has blocked the photo interrupter 135a and reached the position where the shuttle 120 is reversed. Then, the shuttle 120 is inverted by this detection signal, and information recording and reproduction are performed on the optical card 107 by the optical head 121 as described above.

FIG. 12 is a block diagram showing an example of a reciprocating drive device for reciprocating the shuttle by controlling the voice coil type linear motor. 12, 150 power drive system for a power supply voltage to supply a current to the motor driver 154 and 155 V _S, 151 at a lower V _C than the power supply voltage V _S, PLL control circuit 152, polarity switching Circuit 153, MPU (microprocessor unit)
A power supply for a control system for supplying a current to 157. P
The LL control circuit 152 is supplied with a reference clock representing the target speed of the linear motor and an encoder signal of the encoder detector 133 representing the actual speed of the shuttle.
The control circuit 152 outputs a control signal proportional to the phase difference between the two input signals to the terminal a of the switch SW. The switch SW is an electronic switch controlled by the MPU 157, and the intermediate terminal c is connected to the b side when the shuttle is stopped and to the a side when the shuttle is driven. Therefore, when the shuttle is driven, the control signal of the PLL control circuit 152 is output to the polarity switching circuit 153 via the a and c terminals of the switch SW.

The polarity switching circuit 153 is a circuit for switching and controlling the current direction of the linear motor by controlling the polarity of the control signal of the PLL control circuit 152 under the control of the MPU 157 according to the movement direction of the shuttle and acceleration and deceleration. is there. The output signal of the polarity switching circuit 153 is output to the motor driver 154 as a speed control signal of the linear motor. An operational amplifier capable of outputting a large current is used as the motor driver 154, and its output is connected to one terminal of the motor coil 156 of the voice coil type linear motor and the input terminal of the motor driver 155. The motor driver 155 is a large-current inverting amplifier with an amplification factor of 1, and its output is connected to the other terminal of the motor coil 156. Therefore, the output of the motor driver 155 has a polarity opposite to that of the output of the motor driver 154, and the drive current is supplied to the motor coil 156 from the motor drivers 154 to 155 or from the motor drivers 155 to 154 in both directions. An equivalent circuit of the voice coil type linear motor can be represented by a series circuit of a resistance r ₀ and an inductance L as shown in the motor coil 156. Reference numeral 133 is an encoder detector for detecting the speed of the shuttle as described with reference to FIG. 11, and the encoder signal is sent to the PLL control circuit 152 and the MPU 157. 135a and 135b are reverse position detectors for detecting the reverse position of the shuttle.

Next, the reciprocating movement of the shuttle by the reciprocating driving device will be described with reference to FIG. FIG.
13A is a diagram showing the speed of the shuttle, FIG. 13B is a diagram showing the drive current supplied to the motor coil 156 of the voice coil type linear motor, and FIG. 13C is a diagram showing the power supply current of the drive system power supply 150. . First, when driving the shuttle, the polarity switching circuit 153 drives the motor drivers 154 and 155 to apply the acceleration current for accelerating the shuttle to the linear motor coil 156 according to the instruction of the MPU 157.
As a result, the linear motor coil 156 shown in FIG.
Drive current i _e as shown in FIG.
As shown in FIG. 3A, the current is accelerated in the direction corresponding to the current direction. When the shuttle moves, the encoder detector 133 moves accordingly and the encoder signal is output.
It is input to the MPU 157 as a shuttle speed detection signal. The MPU 157 detects the shuttle speed based on this encoder signal. When the target speed is reached, the application of the acceleration drive current is stopped and the PLL control circuit 152 controls the speed.

The PLL control circuit 152 compares the phases of the encoder signal and the CLK signal, which is the target speed signal, and the obtained phase error signal is the switch SW and the polarity switching circuit 15.
3 to the motor drivers 154 and 155. As a result, the motor drivers 154 and 155 drive the linear motor coil 156 according to the phase error signal,
As a result, the shuttle speed is controlled to a constant speed as shown in FIG. Information is recorded and reproduced on the optical card in the constant speed range. When the recording and reproducing of information is completed, the polarity switching circuit 153 drives the motor drivers 154 and 155 to apply a deceleration current for decelerating the shuttle to the linear motor coil 156 according to an instruction from the MPU 157. As a result, as shown in FIG. 13B, the linear motor coil 156 is supplied with the deceleration drive current i _e having the opposite polarity to that at the time of acceleration, and the shuttle is braked as shown in FIG. 13A. In this way, the shuttle gradually slows down, and eventually the reverse position detector 135a or 135b.
When the reverse position is detected at, the c terminal of the switch SW is connected to the b side by the control of the MPU 157, and the movement of the shuttle is stopped. This completes the forward movement of the shuttle. When recording or reproduction is finished and deceleration is started, it is practical to control the MPU 157 to count the encoder signals of the encoder detector 133 and start deceleration after counting a predetermined number. In other words, it is more realistic to measure the movement distance of the shuttle by counting the encoder signals and apply the brake to the shuttle after moving the predetermined distance.

On the other hand, when the shuttle is moved in the opposite direction, the linear motor coil 1 is moved in the same direction as the deceleration direction.
The drive current i _e is supplied to 56 to accelerate the shuttle.
When the target speed is reached, the speed of the shuttle is controlled to be constant, and information is recorded or reproduced on the optical card. And
When the shuttle moves for a predetermined distance, the polarity switching circuit 153 causes the linear motor coil 156 to decelerate the drive current i _e.
Is supplied and the shuttle is braked. As a result, the shuttle is decelerated rapidly and the reverse position detector 13
When the reverse position is detected by 5a or 135b, the c terminal of the switch SW is connected to the b side by the control of the MPU 157, and the movement of the shuttle is stopped in the same manner as described above. In this way, the return movement of the shuttle is completed, and one round trip movement is completed.

Here, the drive current i _e flowing through the linear motor coil 156 during acceleration or deceleration is i _e = V _S
It is determined by / r ₀ (V _S is the voltage of the power supply 150,
r ₀ is the resistance of the linear motor coil 156), the normal resistance r ₀
Is small, the drive current i _e becomes a large current. FIG.
(B) i _e the drive current i _e the acceleration and deceleration periods as a constant in
_Although it is shown as _max , it is actually the linear motor coil 15
Since 6 includes the inductance L, the rising of the current is delayed and the current waveform is somewhat distorted. Further, as described in FIG. 11, the shuttle moving mechanism has a mechanism with very small friction, so that the shuttle is accelerated in proportion to the driving current i _e, and after the target speed is reached, almost no inertia occurs. Move by force. Therefore, the drive current i _e during the constant speed movement of the shuttle is very small as shown in FIG. Since the shuttle moving mechanism has a slight frictional resistance, when the same current is supplied to the linear motor coil 156 during the acceleration period and the deceleration period, the deceleration time becomes slightly shorter than the acceleration time.

Drive current i _e of the linear motor coil 156
As described above, the direction is controlled by the acceleration / deceleration or the moving direction of the shuttle. However, the power supply current i _S of the power supply 150 always flows from positive to negative as shown in FIG.
Always in a fixed direction. The power supply current i _S flows as a bias current of the circuit in addition to the drive current i _e , but this bias current is an amount that can be almost ignored as compared with the drive current i _e . In addition, the PLL control circuit 1 with the power source of the device as one power source
A current may be supplied to the control system such as 52 from the power source 150, but since a large current flows from the power source 150 to generate noise as described above, as shown in FIG. It is common to use a separate power source.

[0017]

As is apparent from the above description, the current supplied to the drive circuit of the voice coil type linear motor is extremely large during the acceleration and deceleration periods as shown in FIG. Other periods are very small or almost zero. That is, during the constant speed period other than the acceleration / deceleration period, the shuttle moves by the inertial force as described above, so that the driving current of the linear motor is small, and the stop period is completely zero. However, in the conventional device shown in FIG. 12, the power supply for the drive system of the linear motor needs to have a current capacity that matches the maximum current i _{e max} of the linear motor, so the power supply is for large currents, and There is a problem that the scale becomes large and the cost becomes high.

The present invention has been made in order to solve such a problem, and by smoothing the current supplied from the power supply to the motor, the maximum current of the power supply is reduced to reduce the scale of the power supply. It is an object of the present invention to provide a moving body reciprocating drive device that can be realized at low cost and at low cost.

[0019]

SUMMARY OF THE INVENTION An object of the present invention is to drive a motor provided as a drive source for a moving body to be driven, and to control the driving means to linearly move the moving body. A moving body reciprocating drive device having a control means for reciprocating the power source, for smoothing a power supply current of the power supply portion between a power supply portion for supplying a drive current to the motor and the driving means. It is achieved by a moving body reciprocating drive device characterized by comprising a smoothing circuit of

[0020]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a first embodiment of the present invention. Note that FIG. 1 shows only the configuration of the drive system of the voice coil type linear motor, and the PLL control circuit 152, the switch SW, and the polarity switching circuit 1 shown in FIG.
The configuration of the control system such as 53, MPU 157, encoder detector 133, reverse position detectors 135a and 135b is omitted. In this embodiment, a smoothing circuit including a resistor 2 and a capacitor 3 is provided at the output of the power source 1 of the drive system, and the drive system is configured to be supplied with current through the smoothing circuit. Further, 4 and 5 are respectively the same as the motor drivers 154 and 155 shown in FIG. 12, the motor driver 4 is a large current operational amplifier, the motor driver 5 is a large current inverting amplifier with an amplification factor of 1, and 6 is It is a motor coil of a voice coil type linear motor. The motor drivers 4 and 5 can supply current to the linear motor coil 6 in both directions as in FIG. 12, and by switching the current direction, acceleration / deceleration of the shuttle and switching of the moving direction are performed. The output signal of the polarity switching circuit 153 of FIG. 12 is input to the 1N terminal of the motor driver 4.

Next, the operation of the first embodiment will be described with reference to FIG. 2 (a) is the shuttle speed, FIG.
(B) is a drive current of a voice coil type linear motor, FIG.
(C) is the drive voltage of the linear motor, FIG. 2 (d) is the power supply 1
Power supply current. Since the control operation of the reciprocating movement of the shuttle has been described in detail with reference to FIG. 13, detailed description thereof will be omitted here. First, when the voice coil type linear motor is driven from the stopped state of the shuttle, the driving current i _e for acceleration is supplied to the linear motor coil 6 by driving the motor drivers 4 and 5 as shown in FIG. 2B. The speed of the shuttle is accelerated toward the target speed as shown in FIG. At this time, the drive current i _e is the power supply current i of the power supply 1.
It becomes the sum of _s and the discharge current i _c of the capacitor 3, and the sum of these two currents is supplied to the linear motor coil 6. When the shuttle accelerates, the drive current i _e flows and the capacitor 3 is discharged, so that the drive voltage V _e decreases slightly as shown in FIG. 2C. Since the drive current i _e is proportional to the drive voltage V _e , the peak value i _{e max} ′ of the drive current i _e is smaller than the conventional peak value i _{e max} indicated by the broken line as shown in FIG. It becomes a small value as much as it decreases. Therefore, the time required for acceleration is slightly longer than before due to the decrease in the peak value, but there is no problem in practice.

On the other hand, the power supply current i _S flows so as to compensate for the discharge of the capacitor 3 as shown in FIG. 2D, that is, it is driven so as to compensate for the current shortage due to the voltage drop of the capacitor 3. It is supplied to the linear motor coil 6 as a part of the current i _e . Therefore, the peak value i _Smax ′ of the power supply current is supplied as a part of the drive current i _e so as to make up for the current shortage of the capacitor 3, so that FIG.
It is significantly smaller than the conventional peak value i _Smax indicated by the broken line.

When the shuttle speed reaches the target speed,
As described above, the shuttle moves almost by inertial force, so that the driving current i _e is supplied only slightly as shown in FIG. 2B. Therefore, since the drive current i _e is small when the shuttle moves at a constant speed, the capacitor 3 is charged with the power supply current i _S , and the drive voltage V _e approaches the power supply voltage V _S as shown in FIG. 2C. At the time of deceleration of the shuttle, the drive current i for deceleration is supplied from the power source 1 and the capacitor 3 to the linear motor coil 6 as in the case of acceleration as shown in FIG. 2B.
_e is supplied. Therefore, the capacitor 3 is discharged as shown in FIG. 2C, and the drive voltage _Ve is slightly lowered. In this case, since the motor deceleration time is shorter than the acceleration time due to the frictional resistance of the shuttle as described above, the charge amount of the capacitor 3 is smaller during deceleration than during acceleration. When the shuttle is stopped, the drive current i _e becomes zero as shown in FIG. 2B, and only a minute bias current flows in the drive system, and the power source 1 passes through the resistor 2 and the capacitor 3
Is charged. Therefore, the voltage of the capacitor 3 approaches the power supply voltage V _S , and the voltage of the capacitor 3 changes to the power supply 1.
It becomes the voltage V _S, the power supply current i _S becomes only the bias current of the circuit, a very small value.

In the present embodiment, the smoothing circuit is provided between the power supply and the drive circuit to smooth the power supply current supplied to the linear motor, so that the maximum drive current of the linear motor during acceleration and deceleration of the shuttle is maximized. The value can be significantly reduced, and the current supply capacity of the power supply 1 can be significantly reduced as compared with the conventional one. That is, the average value of the power consumption does not change, and the time integration of the power supply current does not change. However, the power supply current instantaneously supplied when the shuttle accelerates and decelerates is reduced, so Since it suffices to have a current capacity during deceleration, the current supply capacity of the power supply 1 can be greatly reduced. Further, it is more effective to dispose a coil having an appropriate value in series with the resistor 2 in order to reduce the maximum value i _Smax ′ of the power supply current.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. In the first embodiment, the drive voltage V _e and the power supply current i _S
The amount of fluctuation of is determined by the constants of the resistance value r _S of the resistor 2, the capacitance C of the capacitor 3 and the resistance value r ₀ of the linear motor coil 6 and the duty ratio of the shuttle acceleration, deceleration, constant speed, and stop time. For example, if the capacitance C of the capacitor 3 is infinite, the drive voltage _Ve and the power supply current i _S are constant and do not change. However, since it is difficult to make the capacity C of the capacitor 3 infinite, in practice the drive voltage V
It is impossible to make _e completely constant. for that reason,
The driving voltage V _e fluctuates due to the driving of the linear motor, which may affect the operation of the motor drivers 4 and 5.
Therefore, in the second embodiment, such a problem is solved and an improvement is made so as not to be influenced by the fluctuation of the drive voltage V _e . In FIG. 3, the output of the motor driver 4 is NP
A current amplification circuit including an N-type transistor 7 and a PNP-type transistor 8 is connected, and the output of the motor driver 5 is also connected to the current amplification circuits of an NPN-type transistor 9 and a PNP-type transistor 10. A current is supplied to the current amplification circuits from the smoothing circuit of the resistor 2 and the capacitor 3, and a current is directly supplied from the power supply 1 to the motor drivers 4 and 5.

In this embodiment, the motor drivers 4 and 5
A current amplifier circuit is provided at the output of the motor driver to supply a current from the smoothing circuit, and the motor drivers 4 and 5 are directly supplied with a current from the power source 1 to separate the power sources. The reliability of operation can be improved without being affected by the fluctuation of the driving voltage V _e due to driving. Since the motor drivers 4 and 5 are provided with the current amplifier circuit in the next stage, a large current one is not necessary, and an operational amplifier for a small current is sufficient.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention. This embodiment is an example in which the present invention is applied to an apparatus for driving a linear motor with two positive and negative power supplies as a power supply for a drive system. In FIG. 4, reference numeral 1 is a positive power source, 11 is a negative power source, the positive power source 1 has a smoothing circuit for the resistor 2 and the capacitor 3 as in the first and second embodiments, and the negative power source 11 has a Is provided with a smoothing circuit including a resistor 12 and a capacitor 13. The outputs of these smoothing circuits are connected to the respective current amplification circuits of the outputs of the motor drivers 4 and 5, and are configured to supply current to the current amplification circuits via the smoothing circuits. Further, currents are directly supplied to the motor drivers 4 and 5 from the positive and negative power sources 1 and 11, respectively, and the power sources are separated so that the motor drivers 4 and 5 are not affected by the voltage fluctuation of the smoothing circuit as in the second embodiment. Has been done. As described above, in the device having two power supplies, by providing the smoothing circuit for each power supply, it is possible to obtain the effect that the current capacity of the power supply can be reduced as in the first and second embodiments. Also,
By separating the motor drivers 4 and 5 from the power source of the current amplifier circuit as described above, the operational reliability can be increased as in the second embodiment.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention. In FIG. 5, the same parts as those of the conventional device shown in FIG. 12 are designated by the same reference numerals, and detailed description thereof will be omitted. In the first embodiment shown in FIG. 1, a smoothing circuit composed of a resistor and a capacitor is provided in order to reduce the power source capacity. In such a configuration, the drive current of the linear motor is reduced and the shuttle operates at a constant speed. It takes longer to accelerate to, and longer distances to accelerate. To solve this, for example, the resistor 2 of the smoothing circuit
It is conceivable to reduce the resistance value r _S of the linear motor to suppress the decrease in the drive current of the linear motor. However, since the power supply current increases, there is a limit in reducing the resistance value. Therefore, in the fourth embodiment, as shown in FIG. 5, the resistor 14 and the switch element S are provided in parallel with the resistor 2 which constitutes the smoothing circuit, and the switch element S is synchronized with the constant speed movement and the stop of the shuttle. It controls to turn on. A transistor or the like is used as the switch element S, and the MPU1
The ON / OFF operation is controlled by 57.

The specific operation of this embodiment will be described with reference to FIG. 6 (a) is the shuttle speed, FIG. 6 (b) is the drive current of the linear motor, FIG. 6 (c) is the drive voltage, and FIG.
(D) is a power supply current. First, the MPU 157 detects the speed of the shuttle by monitoring the frequency of the encoder signal of the encoder detector 133, and the MPU 157 supplies the acceleration current to the polarity switching circuit 153 to the linear motor coil 156 until the shuttle reaches the target speed. Instruct to supply. During this acceleration period, the MPU 157 turns off the switch element S, so that when the shuttle is accelerated, as shown in FIG.
As shown in (b), the drive current having the same maximum value i _{e max} as in the conventional case is supplied to the linear motor coil 156. When the shuttle speed reaches the target speed, the PLL control circuit 152 compares the phases of the reference speed signal and the encoder signal, and the shuttle speed is controlled based on the phase error signal. As a result, the speed of the shuttle is controlled to be constant as shown in FIG. 6A, and the shuttle moves at a constant speed.

On the other hand, during this constant speed period, the MPU 15
7 controls the switch element S to be turned on, and the capacitor 3 is charged via the resistors 2 and 14. At this time, since the power supply current i _S flows through both the resistors 2 and 14, the charging time constant is reduced, and the charge-up time of the capacitor 3 is greatly shortened. In the first embodiment, the time constant when the capacitor 3 is charged is C ×
r _S , and if charging was continued with this time constant, it was not possible to fully charge up by the next deceleration. Therefore, the drive voltage V _e does not reach the power supply voltage V _S as shown in FIG. 2C, and the drive current becomes i _{e max} ′ as shown in FIG. 2B and becomes i _{e max} . Could not be reached. In contrast, in this embodiment, the time constant when the capacitor 3 is charged is the resistor 1
By connecting 4 in parallel, the time constant = C (r _S × r _C ) / (r _S + r _C ) ... (1), and the charge-up time of the capacitor 3 is greatly shortened compared to the first embodiment. It is possible to r _C is the resistance value of the resistor 14.

Since the power supply current i _S is obtained by dividing the difference between the power supply voltage V _S and the drive voltage V _e by the resistance of the linear motor coil, the power supply current i _SF when the switch element S is off is i _SF = (V _S −V _e ) / r _S (2) Further, the power supply current i _SN when the switch element S is turned on is i _SN = (V _S −V _e ) (r _S + r _C ) / r _S × r _C (3), and the drive voltage V _e is the same. Then, i _SN > i _SF . This means that the power supply current i _S increases at the moment when the switch element S is turned on, and therefore the power supply current i _S is maximum at i _Smax ′ at the time when the shuttle becomes a constant speed. When the switch element S is turned on,
_Smax ′ will be further increased. Therefore, in this embodiment, as shown in FIG. 6D, the MPU 157 turns on the switch element S after a lapse of a certain time after the shuttle speed becomes constant, thereby preventing the power supply current i _S from increasing. Control. Therefore, as shown in FIG. 6D, the power supply current exponentially decreases from i _Smax ′ when the shuttle has a constant speed, and when the switch element S is turned on, the power supply current i _S increases for a moment. Therefore, it decreases exponentially again with a small time constant as described above.

On the other hand, the drive voltage V _e at the constant speed of the shuttle gradually increases with a large time constant when the switch element S is off as shown in FIG. 6C, and when the switch element S is on, it is as described above. Since the time constant becomes small, it increases rapidly and is almost saturated with the power supply voltage V _S. When the shuttle moves a certain distance in this way, the MPU 157 instructs the polarity switching circuit 153 to supply the deceleration current to the linear motor coil 156, and controls the switch element S to turn off. As a result, the deceleration current is supplied to the linear motor coil 156 as shown in FIG. 6B, and the shuttle starts deceleration as shown in FIG. 6A. The reverse position detector 135a or 13 after the shuttle starts decelerating
When it is detected that the reverse position is reached in 5b, the MPU1
At 57, the switch SW is controlled to stop the shuttle. Further, as shown in FIG. 6 (d), the switch element S is turned on after a fixed time has elapsed since the shuttle stopped, and control is performed so that the power supply current does not increase when the shuttle is stopped, as described above. In this case, it is most efficient that the power supply current i _S when the switch element S is turned on is the same as i _Smax ′, so the resistance values r _S and r _C of the resistors 2 and 14 and the capacitance C of the capacitor 3 are By appropriately selecting the switch element S
It is desirable to set the power supply current when i is turned on to be i _Smax ′. As described above, when the forward movement of the shuttle is completed and subsequently the shuttle is moved to the backward movement, the acceleration current is supplied to the linear motor coil 156 as described above, and the same control is performed thereafter.

In the present embodiment, the resistor 14 and the switch element S are provided in parallel with the resistor 2 of the smoothing circuit, and the switch element S is controlled to be turned on when the shuttle is at a constant speed and when it is stopped. Since the time constant of the smoothing circuit at the time of constant speed and at the time of stop is reduced, the capacitor 3 is charged to the power supply voltage V _S, and the decrease of the drive voltage V _e of the linear motor can be suppressed. Therefore, when the drive voltage V _e is saturated with the power supply voltage V _S , it is clear from a comparison between the drive current of the first embodiment shown in FIG. 2B and the drive current of the present embodiment shown in FIG. 6B. As described above, the maximum value i _emax ′ of the drive current during acceleration / deceleration can be increased to i _emax without changing the power supply current, and the shortage of the drive current due to the decrease in the drive voltage can be effectively eliminated. As a result, the time required for accelerating and decelerating the shuttle to a constant speed does not become long, and the distance required for accelerating and decelerating does not become long. The acceleration / deceleration characteristics of can be greatly improved. In addition, when the switch element S is turned on, the switch element S is turned on after a certain period of time after the shuttle becomes constant speed and after the shuttle is stopped. It is possible to deviate from the peak value of the current, and it is possible to prevent the peak value of the power supply current from newly increasing.

In the fourth embodiment, when the switch element S is turned on, the time after the shuttle becomes constant speed or after it is stopped is measured, and the switch element S is turned on after a certain time has passed. For example, the encoder signal may be counted to measure the travel distance of the shuttle, and the switch element S may be turned on when the shuttle travels by a predetermined distance. Further, as a method of detecting the constant speed state of the shuttle, it may be determined by the phase comparison result of the reference clock and the encoder signal by the PLL control circuit. Further, it is also possible to provide a plurality of time constant circuits of the resistor and the switch element in parallel, and to control so that the switch elements are sequentially turned on when the shuttle is at a constant speed or stopped. That is, by gradually charging up the capacitor, it is possible to further reduce the maximum value of the power supply current. It is also possible to provide two time constant circuits and set each time constant corresponding to the constant speed and stop of the shuttle. That is, since the constant speed time of the shuttle and the stop time are different, the time constants are also set according to those times, and by switching control to the time constant circuit of the optimum time constant at the constant speed and stop of the shuttle, respectively, At the constant speed of the shuttle,
The capacitor can be fully charged up regardless of the stop.

Next, a fifth embodiment of the present invention will be described. The first to fourth embodiments are examples in which the shuttle for mounting the optical card is reciprocally moved so that the light beam of the optical head scans the information track of the optical card. On the contrary, the optical card is fixed. Alternatively, the information beam may be scanned on the information track by reciprocally driving the optical head. Figure 7
Is a diagram showing an example of the mechanism for reciprocally driving the optical head in this way, and 15 is a mounting table for mounting the optical card 107,
Reference numeral 16 is a moving portion which constitutes the optical head, and 17 is a fixed portion. The mounting table 15 does not move in the information track direction (X direction) of the optical card 107, but can move only in the information track crossing direction (Y direction) which is a direction perpendicular to the information track. Therefore, the mounting table 15 moves in the track crossing direction to access a desired information track of the optical card 107.

On the other hand, the moving part 16 of the optical head is the optical card 1
07 has a structure capable of reciprocating in the information track direction (X direction), and the fixing portion 17 has a structure fixed to the machine body.
The moving unit 16 is a mirror for bending the light beam from a direction parallel to the paper surface to a direction perpendicular to the paper surface, an objective lens for narrowing the light beam into a minute light spot, and moving the objective lens in each of tracking and focusing directions. In order to make the moving portion 16 lighter in the fixed portion 17, the semiconductor laser 101, the collimator lens 102, the diffraction grating 103, the polarization beam splitter 104, and the quarter wavelength plate 105 shown in FIG. Optical systems such as are provided. Therefore, in such an optical head moving type apparatus, the shuttle 120 shown in FIG.
May be replaced with the moving unit 16, and in this embodiment, the moving unit 16 is reciprocally driven by each of the driving devices shown in the first to fourth embodiments. Therefore, also in the optical head moving type information recording / reproducing apparatus, it is possible to obtain the same effects as those of the first to fourth embodiments.

FIG. 8 is a diagram showing a sixth embodiment of the present invention. In the figure, 18 is a shuttle for mounting the optical card 107, and 19 is an optical head. Here, the shuttle 18 is fixed, and the optical head 19 is configured to be movable in the information track direction (X direction) and the information track crossing direction (Y direction) by driving a voice coil type linear motor. In this embodiment, the optical head 19 is moved back and forth in the information track direction as in the fifth embodiment, and the optical head 19 is moved in the track crossing direction. The movement of the optical head 19 in the track crossing direction is performed by each of the driving devices of the first to fourth embodiments.

The operation of this embodiment will be described in detail. First, it is assumed that the optical head 19 is stationary at a predetermined home position during recording / reproducing standby. When there is a recording / reproducing command, the moving distance is obtained from the difference between the current position of the optical head 19 and the designated information track, and the optical head 19 is moved to the target track based on the moving distance. When the target track is reached, recording or reproduction is performed on that track, and when the recording or reproduction is completed, the optical head 19 moves to the original position again, and the movement of one round trip is completed. Of course, when the optical head 19 moves toward the target track and returns to the original position, control is performed in the processes of acceleration, constant speed, deceleration, and stop.

Here, when the light spot scans the information track, there is a high possibility that the light spot will be repeatedly reciprocally scanned, but when the light spot is moved in the information track crossing direction, when the desired track is accessed. Therefore, this is not normally repeated continuously. That is, the frequency of movement of the optical head 19 in the track crossing direction is considerably smaller than that in the former case, and the movement distance is also different. Therefore, when the optical head 19 is moved in the track traversing direction, the constant speed period of the optical head 19 varies depending on the track to be accessed, and the stop period is the information recording and reproducing time. Significantly longer than when accessing a truck. Therefore, in the present embodiment, the stop period of the optical head 19 is long, and the capacitor of the smoothing circuit is sufficiently charged up during that period, which is very effective in saturating the drive voltage of the linear motor to the power supply voltage. is there. Since the sixth embodiment described above moves the optical head in the track crossing direction, the recording medium is not limited to an optical card. For example, it goes without saying that the present invention can be applied to an apparatus for moving an optical head in the track crossing direction of an optical disc having a spiral track.

[0040]

As described above, according to the present invention, the smoothing circuit is provided and the power supply current supplied to the motor is smoothed, so that the maximum current of the power supply current can be greatly reduced as compared with the conventional one. The power supply can be downsized and
This has the effect of reducing the cost of the device.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a time chart showing the operation of the first embodiment of the present invention.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a third embodiment of the present invention.

FIG. 5 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 6 is a time chart showing the operation of the fourth embodiment of FIG.

FIG. 7 is a plan view showing a fifth embodiment of the present invention.

FIG. 8 is a plan view showing a sixth embodiment of the present invention.

FIG. 9 is a block diagram showing an optical system of a conventional optical information recording / reproducing apparatus.

FIG. 10 is a diagram showing a recording surface of an optical card of a conventional example and the speed of the optical card when the optical card is reciprocally moved and a light beam is relatively scanned, corresponding to a recording area.

FIG. 11 is a perspective view showing an example of a reciprocating mechanism of an optical card in a conventional optical information recording / reproducing apparatus.

12 is a circuit diagram showing an example of a reciprocating drive device for an optical card in the reciprocating mechanism of FIG.

FIG. 13 is a time chart showing the operation of the drive device in FIG.

[Explanation of symbols]

 1, 11 Power supply 2, 12, 14 Resistor 3 Condenser 4,5 Motor driver 7-10 Transistor 6 Linear motor coil 133 Encoder detector 135a, 135b Inversion position detector 152 PLL control circuit 153 Polarity switching circuit 157 MPU SW switch S Switch element

Claims (16)

[Claims] 1. A drive means for driving a motor provided as a drive source of a moving body to be driven, and a control means for controlling the driving means to linearly reciprocate the moving body. In the moving body reciprocating drive having the above, a smoothing circuit for smoothing a power supply current of the power supply unit is provided between a power supply unit for supplying a drive current to the motor and the driving unit. And a moving body reciprocating drive device. 2. The moving body reciprocating drive device according to claim 1, wherein the smoothing circuit includes a resistor or a series circuit of a resistor and a coil and a capacitor. 3. The power supply unit comprises a first power supply unit and a second power supply unit, the first power supply unit supplies a current to the control means, and the second power supply unit performs the smoothing. 2. The reciprocating drive device for a moving body according to claim 1, wherein a current is supplied to the drive means via a circuit. 4. The driving means comprises a voltage amplification section and a current amplification section for current-amplifying the output of the voltage amplification section. The voltage amplification section is directly supplied with current from the power supply section, and the current amplification section is provided. 2. The moving body reciprocating drive device according to claim 1, wherein a current is supplied to the section from the power source section through a smoothing circuit. 5. The driving means is driven by two positive and negative power supplies, and a smoothing circuit for smoothing the power supply current of each power supply unit is provided between the positive and negative power supplies and the driving means. The moving reciprocating drive device according to claim 1, wherein 6. The control means accelerates the moving body until it reaches a target speed, and when it reaches the target speed, controls it at a constant speed based on a phase difference between a reference speed signal and a speed signal of the moving body. 2. The moving body reciprocating drive device according to claim 1, wherein when the moving body has moved a predetermined distance, a brake is applied to decelerate, and when the moving body reaches a position to be reversed, the moving body is stopped to control the reciprocating movement of the moving body. . 7. The shuttle is a shuttle for mounting a card-shaped optical information recording medium having a plurality of linear tracks, and the shuttle is linearly reciprocated to transfer information. 2. The reciprocating drive unit for a moving body according to claim 1, wherein a recording or reproducing light beam is scanned on a linear track of a recording medium placed on the shuttle. 8. The moving body is an optical head for irradiating a card-shaped optical information recording medium having a plurality of linear tracks with a light beam for recording or reproducing information,
2. The reciprocating drive device for a moving body according to claim 1, wherein a linear beam of the information recording or reproducing scans a linear track of the recording medium by linearly reciprocating the optical head. 9. The moving body is an optical head for irradiating a light beam for recording or reproducing information on an optical recording medium having a plurality of tracks, and moving the optical head in a track crossing direction. 2. The reciprocating drive unit for a moving body according to claim 1, wherein the optical head accesses a target track of the recording medium according to. 10. The moving body reciprocating drive device according to claim 9, wherein the optical recording medium is a card-shaped recording medium having a plurality of linear tracks. 11. The movable body reciprocating drive device according to claim 9, wherein the optical recording medium is a disk-shaped recording medium having spiral tracks. 12. The smoothing circuit has a time constant variable circuit for varying the time constant of the smoothing circuit, and the time constant of the time constant variable circuit is provided when the moving body moves at a constant speed and when it stops. 2. The reciprocating drive device for a moving body according to claim 1, wherein the time constant of the smoothing circuit is reduced by a variable operation. 13. The reciprocating drive for a moving body according to claim 12, wherein the variable time constant circuit is composed of a series circuit of a resistor and a switch element, and the time constant is reduced by turning on the switch element. apparatus. 14. The variable time constant circuit reduces the time constant after a predetermined time elapses or after moving a predetermined distance after the moving body has reached a constant speed and stopped, respectively. The moving body reciprocating drive device according to claim 12. 15. The time constant variable circuit is composed of a series circuit of a plurality of resistors and a switch element, each of which is provided in parallel, and when the time constant is reduced when the moving body moves at a constant speed or when stopped, 13. The moving body reciprocating drive device according to claim 12, wherein the plurality of switch elements are turned on stepwise. 16. The reciprocating drive device for a moving body according to claim 1, wherein the motor is a voice coil type linear motor.