JPH07121884A - Device for recording/reproducing optical information - Google Patents

Abstract

PURPOSE:To simply control a rotational dirrection of an ultrasonic motor without requiring a complex control circuit by varying a drive voltage amplitude and controlling the rotational dirrection of the ultrasonic motor. CONSTITUTION:This device is provided with the ultrasonic motor 21 for moving either one side of a shuttle placing an optical card or an optical head in the traverse dirrection of a track and an MPU 5, a pulse width setting circuit 16 varying the drive voltage amplitude of the ultrasonic motor 21. By moving the shuttle or the optical head in the traverse dirrection of the track, a positional relation between an optical beam and the information track is corrected, and by varying the drive voltage amplitude of the ultrasonic motor 21 with the MPU 5, the pulse width setting circuit 16, the rotational dirrection of the ultrasonic motor 21 is controlled, and the moving dirrection of the shuttle or the optical head is switched.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus for optically recording / reproducing information on / from a card-shaped recording medium.

[0002]

2. Description of the Related Art Conventionally, various types of recording media, such as disc-shaped and card-shaped, are known as a recording medium for optically recording information or optically reading recorded information. Among these information recording media, a card-shaped recording medium (hereinafter referred to as an optical card) is small and lightweight, convenient to carry, and has a large recording capacity, so that great demand is expected in the future.

When information is recorded on a recording medium such as an optical card, the information track is optically scanned by scanning the information beam with a light beam which is modulated according to the recording information and focused into a minute light spot. Information is recorded as a recordable pit string. When recording this information,
In order to accurately record information without causing trouble such as intersection with the information track, the irradiation position of the light beam is controlled in the direction orthogonal to the track, and the light beam automatically scans to follow the information track. Tracking control is performed. Needless to say, auto-tracking control is performed even during reproduction of information, and the light beam is controlled so as to follow the information track for scanning.

FIG. 4 is a block diagram showing an example of an optical card recording / reproducing apparatus for recording / reproducing information on / from the optical card. In the figure, 100 is an optical card which is an information recording medium, 101
Is a shuttle for mounting the optical card 100. The shuttle 100 is configured so that it can be moved in the cross-track direction by driving an ultrasonic motor (hereinafter abbreviated as USM) 103. By moving the light beam in the cross-track direction under the control of the USM control circuit 104, the shuttle 100 will be described later. As described above, the correction control for the skew of the optical card 100 is performed. Reference numeral 105 is a semiconductor laser which is a light source for recording and reproduction, and 106 is a collimator lens for collimating the light beam of the semiconductor laser 105.

The light beam of the semiconductor laser 105 is incident on the objective lens 108 via the collimator lens 106 and the polarization beam splitter 107, where it is focused into a minute light spot and is irradiated onto the optical card 100. This irradiation light is reflected on the surface of the optical card 100, and the reflected light passes through the objective lens 108 again to become parallel light, and further passes through the polarization beam splitter 107 and is guided to the polarization beam splitter 109. Then, it is reflected by the polarization beam splitter 109, condensed by the condenser lens 110, and received by the photoelectric conversion element 111 for tracking control.
Optical elements such as the semiconductor laser 105, the objective lens 108, and the photoelectric conversion element 111 described above are integrated as an optical head 102, and are configured to be capable of reciprocating in the track direction with respect to the optical card 100. Therefore, when the optical head 102 reciprocates, the light beam of the optical head 102 and the optical card 100 on the shuttle 101 relatively reciprocate, and the light beam scans the information track.
The optical head 102 may be fixed, and the shuttle 101 may reciprocate in the track direction.

The light reception signal of the photoelectric conversion element 111 is input to the tracking control circuit 112, and the tracking control circuit 112 generates a tracking error signal indicating the deviation amount and the deviation direction of the light beam with respect to the track based on the light reception signal. It Then, the tracking control circuit 112
Then, the tracking actuator 113 is driven based on the tracking error signal, and the objective lens 108 is slightly moved in the direction orthogonal to the track so that the light beam does not deviate from the information track during the scanning of the light beam as described above. Is done. In this way, the tracking of the light beam is controlled, and when recording or reproducing information, the recording or reproducing of information is performed under the tracking control.

Here, the information track of the optical card 100 is not parallel to the track direction as shown in FIG.
It may have a skew angle θ with a slight inclination. When an optical card having such a skew is subjected to tracking control to scan a light beam, the objective lens 108 has a limited movable range, so the light beam is out of the control range of the tracking control and cannot follow the information track. It may happen. Therefore, in such a case, the USM 103 moves the shuttle 101 in the track crossing direction to perform the skew correction control. Specifically, first, the objective lens 108
The movable range of the optical head 102 is 25 μm to the left and right from the lens center position, and
As described above, it is assumed that the information track of the optical card having the skew angle θ is scanned. Even if there is a skew at this time, when the information track is within the movable range of the objective lens 108, the objective lens 108 is driven according to the skew by the tracking control, so that the light beam scans following the information track. .

On the other hand, the objective lens 108 is the optical head 102.
25 μm, which is the movable range from the center position to the left or right
Move the tracking control circuit 112 to the USM
A control signal is output to the control circuit 104 to move the shuttle 101 and return the objective lens 108 to the center of the optical head 102. As a result, the USM control circuit 104 controls the USM 103 to move the shuttle 101 in the track crossing direction. In this state, the tracking control is working. Therefore, the objective lens 108 also follows the shuttle 101 and moves toward the center of the optical head 102. Move to.

In this case, in the USM control circuit 104, the US
In order to drive M103, a two-phase sine wave drive signal whose phase is shifted by 90 degrees is output. For example, if the two-phase drive signals are A phase and B phase, B phase is 90 degrees with respect to A phase. The rotation direction of the USM 103 is controlled by advancing or delaying by 90 degrees. Then, when the objective lens 108 is located at the center of the optical head 102 and the objective lens 108 comes to the center of the movable range, the tracking control circuit 112 causes the USM to move.
A control signal is output to the control circuit 104 to stop the shuttle 101. If there is a skew in the optical card 100 in this way, the objective lens 108 is controlled to return to the center of the optical head 102 by moving the shuttle 101, and correction control of the positional relationship between the light beam and the information track is performed. Be seen.

[0010]

However, in the above-mentioned conventional information recording / reproducing apparatus, the USM is rotated in two directions.
Since the phase of the phase drive signal is controlled by advancing or delaying the phase by 90 degrees, the configuration of the USM control circuit becomes complicated, and there is a problem that the scale of the device is increased and the cost is increased accordingly. .

The present invention has been made in view of the above conventional problems, and an object thereof is to change the drive voltage amplitude to obtain USM.
It is an object of the present invention to provide an optical information recording / reproducing apparatus capable of easily controlling the rotation direction of the USM by controlling the rotation direction of the USM without requiring a complicated control circuit.

[0012]

SUMMARY OF THE INVENTION An object of the present invention is to relatively reciprocate an optical information recording medium having a linear information track and an optical head, and to emit a light beam emitted from the optical head. In an optical information recording / reproducing apparatus for recording or reproducing information by scanning on an information track by tracking control, either a shuttle for mounting the recording medium or an optical head is moved in the transverse direction of the information track. And a variable amplitude circuit for changing the amplitude of the drive voltage of the ultrasonic motor, and by moving the shuttle or the optical head in the track crossing direction by the ultrasonic motor, And the position relationship of the information track are corrected, and the drive voltage amplitude of the ultrasonic motor is adjusted by the amplitude variable circuit. By reduction, it controls the rotation direction of the ultrasonic motor is achieved by an optical information recording and reproducing apparatus characterized by switching the direction of movement of the shuttle or optical head.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the optical information recording / reproducing apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a photodetector for detecting reflected light from two light spots for tracking control, which are emitted from a semiconductor laser as a light source to an optical card. The photodetector 1 corresponds to the photoelectric conversion element 111 shown in FIG. The two light spots for tracking control are generated, for example, by dividing a light beam of a semiconductor laser into a main beam and two side beams, and two of these side beams are used as an optical card for tracking control. It is irradiated to two tracking tracks provided on both sides of the information track. The photodetector 1 includes detection pieces 1a and 1b corresponding to the two light spots, and the reflected lights of the two light spots reflected from the tracking track are detected by the detection pieces 1a and 1b, respectively. The detection signals of the detection pieces 1a and 1b are differentially detected by the differential amplifier 2 and output as a tracking error signal. The tracking error signal is binarized by the comparator 10 at a predetermined slice level and output to the MPU 5. The MPU 5 is a microprocessor circuit for controlling each part of the device.

Reference numeral 3 is a differential amplifier to which a predetermined voltage is input from the MPU 5 via the D / A converter 4 when a track jump is performed by the objective lens 9. However, at the time of track jump, the tracking servo loop is turned off by a switch (not shown). Further, at the time of this track jump, the tracking error signal of the differential amplifier 2 is binarized by the comparator 10 and input to the MPU 5, where M
Based on this input signal, the PU 5 controls to pull the light beam to the target information track again at the zero cross point. Reference numeral 6 is a phase compensator for stabilizing the tracking servo loop, and 7 is power amplification of a tracking error signal to perform a tracking actuator coil (AT coil) 8
Is an AT coil driver for driving the light source, and 9 is an objective lens for condensing the light beam of the semiconductor laser of the light source and irradiating it as a minute light spot on the optical card. The tracking error signal detected by the differential amplifier 2 is transmitted to the AT via the differential amplifier 3, the phase compensator 6, and the AT coil driver 7.
Tracking control is performed to output the light spot to the coil 8 and drive the AT coil 8 with a tracking error signal to slightly move the objective lens 9 in the tracking direction to scan the light spot by following the information track.

Reference numeral 11 denotes a lens position sensor for detecting the position of the objective lens 9 in the tracking direction. The lens position sensor 11 includes two light receiving elements 11a and 11b, and a reflecting plate (not shown) is attached to the lens barrel side surface of the objective lens 9 so as to face the lens position sensor 11. The reflecting plate is irradiated with light from a light emitting element (not shown), and the reflected light is received by the light receiving element 1 of the position sensor 11.
It is detected by 1a and 11b. In this case, the position sensor 11
Since the light receiving amounts of the light receiving elements 11a and 11b vary depending on the position of the objective lens 9 in the tracking direction, when the detection signals of the light receiving elements 11a and 11b are differentially detected by the differential amplifier 12, the position of the objective lens 9 is detected. A corresponding lens position signal can be obtained. This lens position signal is digitized by the A / D converter 13 and taken into the MPU 5.

Reference numeral 14 is a D / A converter for applying an analog voltage to a voltage controlled oscillator (VCO) 15 based on an instruction from the MPU 5. The VCO 15 performs voltage / frequency conversion by changing the frequency of the output signal according to the input voltage, and outputs the output signal f having a frequency corresponding to the input voltage.
d is output. 16 is VC based on the instruction of MPU5
A pulse width setting circuit for converting the pulse width of the output signal fd of O15 into an output signal fw having a predetermined pulse width. By changing the pulse width of the pulse width setting circuit 16 as described later in detail, the USM 21 is driven. By changing the voltage amplitude, the rotation direction of the USM 21 can be switched. Reference numeral 17 divides the output signal fw of the pulse width setting circuit 16 by 4 and divides the divided signal into 4 sets of signals.
It is a ring counter for shifting the phases of the pair of signals by 90 degrees and outputting them. Reference numeral 18 denotes a changeover switch for turning on or off the output signal of the ring counter 17 based on an ON / OFF drive signal that indicates whether to drive or stop the USM 21 output from the MPU 5. 19 is a drive circuit for amplifying the output of the changeover switch 18, 20 is a booster circuit for boosting the output of the drive circuit 19, 21 is the shuttle 101 on which the optical card 100 is mounted as described in FIG. USM for moving in the cross-track direction.

Next, a specific operation of the above embodiment will be described. First, when recording or reproducing information, either one of the optical head and the optical card reciprocates in the track direction, and the light beam of the optical head and the optical card are relatively reciprocating. At this time, the tracking servo loop from the photodetector 1 to the AT coil 8 in FIG. 1 is in the ON state, and the light beam emitted from the optical head by the tracking control operation scans the information track of the optical card. It is assumed that Although not shown in FIG. 1, a focus servo loop for focusing the light beam on the optical card surface is also provided, and the light beam emitted from the optical card by the focus control operation is directed to the card surface. It is assumed that the information track is scanned while maintaining the in-focus state.

Here, the optical card has a skew as described with reference to FIG. 5. Therefore, when tracking control is applied by the tracking servo loop, the objective lens 9
Moves in the tracking direction according to the skew.
The movable range of the objective lens 9 in the tracking direction is, for example, ± 25 μm with the center position of the optical head as the center. The position of the objective lens 9 in the tracking direction is detected by the lens position sensor 11, and the output thereof is captured by the A / D converter 13 in the MPU 5. That is, MP
At U5, the position of the objective lens 9 is monitored, and as described above, the objective lens 9 moves according to the skew, and when the objective lens 9 eventually moves to the limit of the movable range, the MPU
In No. 5, the USM 21 is driven to move the shuttle on which the optical card is placed in the tracking direction so that the objective lens 9 is returned to the center of the optical head.

The control operation of the USM 21 will be described. FIG. 2 is a time chart showing signals of various parts of the control circuit for controlling the drive of the USM 21, and FIG.
This is the output signal of CO15. When the device is operating, MPU
A predetermined voltage is input to the VCO 15 from the VCO 15 via the D / A converter 14, and the VCO 15 converts the input voltage into a frequency as shown in FIG. 2A to generate a pulse signal having a predetermined frequency according to the input voltage. Is output. Figure 2
(B) is an output signal of the pulse width setting circuit 16. The pulse width setting circuit 16 receives the VCO based on the instruction from the MPU 5.
The pulse width of the output signal of 15 is variable, and the rotation direction of the USM 21 is controlled by changing the drive voltage amplitude of the USM 21 by controlling this pulse width. 2 (c)-
(F) is an output signal of the ring counter 17. In the ring counter 17, the output signal of the pulse width setting circuit 16 is divided by 4 and the phase of the divided signal is shifted by 90 degrees as shown in FIGS. 2C to 2F into 4 sets of signals. The signals are separated and output as signals A ₁ , A ₂ and B ₁ , B ₂ .

Here, when the objective lens 9 moves to either the left or right of the tracking direction due to the skew, and the lens position sensor 11 detects that the objective lens 9 has moved to near the movable range limit of 25 μm, the MPU 5
Then, the ON signal for instructing the driving of the USM 21 is output to the changeover switch 18. At the same time, the MPU 5 outputs a signal instructing the pulse width to the pulse width setting circuit 16. At this time, the MPU 5 recognizes which of the left and right directions the objective lens 9 has moved based on the output signal of the lens position sensor 11, and determines the rotation direction of the USM 21 to move the shuttle according to the movement direction. The pulse width of the pulse width setting circuit 16 is controlled according to the rotation direction.

The pulse width is determined as follows. First, if the pulse width of the pulse width setting circuit 16 is widened, U
There is a characteristic that the drive voltage amplitude of the SM 21 becomes large, and the drive voltage amplitude becomes small when the SM 21 is narrowed. Further, when the drive voltage amplitude of the USM 21 is changed, as shown in FIG. 3, the USM 21 rotates clockwise when the amplitude is equal to or larger than a predetermined amplitude, and when the amplitude is equal to or smaller than the predetermined amplitude, the rotation direction reverses and rotates counterclockwise. There is a characteristic of doing. Therefore, in the MPU 5, the pulse width of the pulse width setting circuit 16 is determined in advance corresponding to the rotation direction of the USM 21 from the relationship between the pulse width and the drive voltage amplitude and the relationship between the drive voltage amplitude and the rotation direction. When the drive voltage amplitude of the USM 21 is determined corresponding to the rotation direction, there is a dead zone where the rotation speed becomes 0 in the relationship between the drive voltage amplitude and the rotation speed as shown in FIG. 3, so avoid this. The drive voltage amplitude is determined.

In this way, in the MPU 5, the pulse width of the pulse width setting circuit 16 is widened as shown by the broken line or as shown by the solid line in order to control the rotation direction of the USM 21, as shown in FIG. 2B. It is controlled whether to narrow.
The output signal of the pulse width setting circuit 16 is the ring counter 17
Then, as shown in FIGS. 2C to 2F, the signals are separated into four signals whose phases are shifted by 90 degrees and are output to the drive circuit 19 via the changeover switch 18. In this case, the drive circuit 19 generates two sinusoidal drive signals whose phases are shifted by 90 degrees on the basis of the four signals of the ring counter 17 and applies the drive signals to the G and H terminals of the USM 21 via the booster coil 20, respectively. It The amplitude of the drive signal applied to the USM 21 changes according to the pulse width of the pulse width setting circuit 16. The wider the pulse width, the larger the amplitude, and the narrower the width, the smaller the amplitude. Therefore, by changing the drive voltage amplitude corresponding to the rotation direction as described in FIG. 3, the USM 21 rotates in the corresponding direction, and the shuttle also moves to return the objective lens 9 to the center of the optical head. Go.

As a result, the optical card on which the shuttle is mounted also moves, the information track on which the light beam is currently irradiated moves toward the center of the optical head, and the objective lens 9 also works by the tracking servo. Following the movement of the shuttle, it moves toward the center of the optical head. When the lens position sensor 11 detects that the objective lens 9 has moved to the center of the optical head, the MPU 5 outputs an OFF signal for instructing the changeover switch 18 to stop driving the USM 21. By this off signal, the output of the output signal of the ring counter 17 to the drive circuit 19 is turned off in the changeover switch 18, and the driving of the USM 21 is stopped. In this way, the objective lens 9 returns to the center of the optical head, and thereafter, tracking control is performed by moving the objective lens 9 slightly in the tracking direction by the tracking servo, and information is recorded or reproduced on the information track. .

In the present embodiment, the pulse width of the pulse width setting circuit 16 is changed in accordance with the rotation direction of the USM 21, so that the drive voltage amplitude of the USM 21 is two predetermined drives corresponding to the clockwise direction and the counterclockwise direction. Since the voltage amplitude is changed, the rotation direction of the USM 21 can be easily controlled without requiring a complicated circuit. That is, when the rotation direction of the USM 21 is switched, the phase of the two-phase drive signal is controlled by the switch or the like as described above, but in the present embodiment, a circuit for such complicated phase switching is unnecessary, and it is simple. The circuit can control the rotation direction of the USM 21.

In the above embodiment, the USM drive voltage amplitude is changed by changing the pulse width of the pulse width setting circuit. However, the present invention is not limited to this.
The drive voltage amplitude can also be changed by changing the pulse voltage of the pulse signal from CO. Although the shuttle is moved in the cross-track direction, the shuttle may be fixed in the cross-track direction and the optical head may be moved in the cross-track direction by driving the USM.

[0026]

As described above, according to the present invention, the rotation direction of the ultrasonic motor is controlled easily by changing the drive voltage amplitude to control the rotation direction of the ultrasonic motor, without requiring a complicated control circuit. Has the effect of controlling.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an optical information recording / reproducing apparatus of the present invention.

FIG. 2 is a time chart showing the output signals of the VCO, pulse width setting circuit and ring counter of the embodiment of FIG.

3 is a characteristic diagram showing the relationship between the drive voltage and the rotation direction of the ultrasonic motor of the embodiment of FIG.

FIG. 4 is a block diagram showing a conventional optical card information recording / reproducing apparatus.

FIG. 5 is a diagram showing skew of an optical card.

[Explanation of symbols]

 1 Photodetector 2, 3 Differential Amplifier 5 MPU 8 AT Coil 9 Objective Lens 14 D / A Converter 15 Voltage Controlled Oscillator (VCO) 16 Pulse Width Setting Circuit 17 Ring Counter 18 Changeover Switch 19 Drive Circuit 20 Booster Coil 21 Ultrasonic Wave Motor (USM)

Claims (2)

[Claims] 1. An optical information recording medium having a linear information track and an optical head are relatively moved back and forth, and a light beam emitted from the optical head is scanned on the information track by tracking control. Due to
In an optical information recording / reproducing apparatus for recording or reproducing information, an ultrasonic motor for moving either a shuttle for mounting the recording medium or an optical head in a transverse direction of an information track, and the ultrasonic motor. And an amplitude variable circuit for changing the amplitude of the drive voltage, and by moving the shuttle or the optical head in the track crossing direction by the ultrasonic motor, the positional relationship between the light beam and the information track is corrected, and An optical information recording / reproducing apparatus characterized in that the amplitude variable circuit changes the drive voltage amplitude of the ultrasonic motor to control the rotation direction of the ultrasonic motor and switch the moving direction of the shuttle or the optical head. 2. The amplitude variable circuit, based on an instruction from the control circuit, outputs a pulse signal having a predetermined frequency based on an instruction from the control circuit, and a pulse width of the pulse signal from the voltage controlled oscillator based on an instruction from the control circuit. A variable pulse width setting circuit, and a pulse width of the pulse width setting circuit is set to two pulse widths, a wide pulse width and a narrow pulse width, which are determined according to the drive voltage of the ultrasonic motor and the characteristics of the rotation direction. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the drive voltage amplitude of the ultrasonic motor is changed by changing the drive voltage amplitude.