JPH07121886A - Device for recording/reproducing optical information - Google Patents

Abstract

PURPOSE:To prevent the increase in a tracking actuator (AT) error amount and to stabilize operation by suppressing the rapid acceleration and the rapid deceleration of a shuttle. CONSTITUTION:This device is provided with an ultrasonic motor 21 for moving either one side of the shuttle placing an optical card or an optical head in the traverse dirrection of a track and control circuits 5, 14-18 for controlling the drive speed of the ultrasonic motor 21 at the drive start time and the drive stop time of the ultrasonic motor 21. When the information track is scanned by the light beam of the optical head, by moving the shuttle or the optical head in the traverse dirrection of the track by the ultrasonic motor 21, a positional relation between the light beam and the information track is corrected. Then, by gradually raising the drive speed of the ultrasonic motor 21 by the control circuits at the drive start time of the ultrasonic motor 21, and by gradually lowering it at the drive stop time, the shuttle or the optical head is accelerated or decelerated gradually.

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.

By the way, when information is recorded on a recording medium such as an optical card, it is optically detected by scanning an information track with a light beam which is modulated according to the recorded information and is focused on a minute light spot. Information is recorded as a sequence of possible recording pits. When recording this information,
In order to record information accurately without causing trouble such as intersection with the information track, the irradiation position of the light beam is controlled in the track crossing direction, and auto tracking is performed so that the light beam scans following the information track. 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. 13 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, and 10
Reference numeral 1 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 101. Therefore, when the optical head 102 reciprocates, the light beam of the optical head 102 and the optical card 100 relatively reciprocate, and the light beam scans the information track. The optical head 10
2 is fixed in the track direction, 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 track crossing direction so that the light beam does not deviate from the information track during 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 may not be parallel to the track direction as shown in FIG. 14 but may be slightly inclined to have a skew angle θ. When an optical card with such a skew is subjected to tracking control and a light beam is scanned, the objective lens 108
Has a limited movable range, the light beam may be out of the control range of the tracking control and may not be able to follow the information track. Therefore, in such a case, the USM 103 moves the optical card 100 in the track crossing direction to perform the correction control for the skew. Specifically, first, the objective lens 10
It is assumed that the movable range of 8 is 25 μm to the left and right from the lens center position, and the light beam of the optical head 102 scans the information track of the optical card having the skew angle θ as shown in FIG. 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 order to drive the USM 103, the USM control circuit 104 outputs a two-phase sine wave drive signal with a phase difference of 90 degrees. The objective lens 108 is the optical head 102.
When the objective lens 108 comes to the center of the movable range at the center of the, the tracking control circuit 112 outputs a control signal to the USM 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.

[0009]

However, in the above-mentioned conventional information recording / reproducing apparatus, the USM is used as the driving means for moving the shuttle in the track crossing direction. If the shuttle is used, the shuttle is rapidly accelerated when the USM starts to be driven, and is rapidly decelerated when the USM is stopped. Therefore, there is a problem that the tracking error amount (AT error amount) is increased at the time of starting and stopping the USM drive, and if the AT error amount is too large, AT disconnection occurs.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to suppress the rapid acceleration and the rapid deceleration of the shuttle to prevent an increase in the AT error amount, thereby stabilizing the operation of the optical system. An object is to provide an information recording / reproducing device.

[0011]

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. In order to scan the information track with the light beam of the optical head, a drive means for controlling the drive speed of the drive means and a control means for controlling the drive speed of the drive means at the time of starting and stopping the drive of the drive means are provided. By moving the shuttle or the optical head in the track crossing direction by the driving means, the positional relationship between the light beam and the information track is determined. The driving speed of the driving means is gradually increased by the control means when the driving means starts driving, and is gradually decreased when the driving is stopped, thereby gradually accelerating or decelerating the shuttle or the optical head. It is achieved by a characteristic optical information recording / reproducing apparatus.

[0012]

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. This 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). Also, 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.
Based on this input signal, the MPU 5 controls the light beam to be drawn into 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 passed through the differential amplifier 3, the phase compensator 6, and the AT coil driver 7 to A
Tracking control is performed in which the light spot is output to the T coil 8 and the AT coil 8 is driven by a tracking error signal, and the objective lens 9 is finely moved in the tracking direction to scan the light spot by following the information track.

Reference numeral 11 is 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. Light is emitted from a light emitting element (not shown) to the reflecting plate, and the reflected light is reflected by the two light receiving elements 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 the 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. Reference numeral 17 divides the output signal fw of the pulse width setting circuit 16 by 4 and divides the divided signal. It is a ring counter for dividing into four sets of signals and for shifting the phases of the four sets of signals by 90 degrees and outputting them. 18 is the US output from MPU5
ON to instruct M21 to drive or stop
/ OFF drive signal and USM21 forward rotation,
It is a changeover switch for selectively outputting the output signal of the ring counter 17 based on the FWD / REV signal indicating the reverse rotation or the rotation direction. Reference numeral 19 is a drive circuit for power amplifying the output of the changeover switch 18, 20 is a booster circuit for boosting the output of the drive circuit 19, 2
Reference numeral 1 is a USM for moving the shuttle 101 on which the optical card 100 is mounted in the cross-track direction as described in FIG.

Next, a specific operation of the above embodiment will be described. First, at the time of recording or reproducing information, 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 photodetector 1 of FIG.
It is assumed that the tracking servo loop from the AT coil to the AT coil 8 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. 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 in FIG. 14, and therefore, when tracking control is performed 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 around the center position of the objective lens 9. 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, the MPU 5 monitors the position of the objective lens 9,
As described above, the objective lens 9 moves according to the skew,
When the objective lens 9 eventually moves near the limit of the movable range, 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 returns to the center of the optical head. .

The control operation of the USM 21 will be described. First, FIG. 2 is a time chart showing signals of respective parts of the control circuit for controlling the drive of the USM 21, and FIG.
2A shows the output signal of the VCO 15, and FIG. 2B shows the output signal of the pulse width setting circuit 16. When the device is operating, M
A predetermined voltage is input from the PU 5 to 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.
Further, the MPU 5 outputs a control signal for instructing the pulse width to the pulse width setting circuit 16, and the pulse width setting circuit 16 sets the pulse width based on the instruction.
A pulse signal having a pulse width instructed as in (b) is output. The ring counter 17 divides this pulse signal by four, and separates the divided signal into four sets of signals by shifting the phase by 90 degrees as shown in FIGS. 2 (c) to (f). It is output as ₁ , A ₂ , and B ₁ , B ₂ . The output signal of the ring counter 17 is output to the changeover switch 18, and the changeover switch 18 drives the USM 21 based on the ON / OFF drive signal instructing the drive from the MPU 5 and the FWD / REV signal instructing the rotation direction. MP when normal USM21 is not driven
An off signal is output from U5 to the changeover switch 18, and the changeover switch 18 does not output a signal to the drive circuit 19 in accordance with this instruction, and the USM 21 is maintained in the stopped state.

Here, in the MPU 5, the output of the lens position sensor 11 causes the objective lens 9 to move to the left or right in the tracking direction, which is the limit of the movable range of 25 μ, as described above.
When it recognizes that it has moved near m, the changeover switch 18
An ON signal for instructing to drive the USM 21 is output to. At the same time, the MPU 5 recognizes the moving direction of the objective lens 9 based on the output of the lens position sensor 11 and accordingly U
A signal for instructing the rotation direction of the SM 21 is provided with the changeover switch 18
Output to. In FIG. 1, a signal indicating the rotation direction is FWD.
Although shown as the / REV signal, the FWD signal is output when instructing rotation in the forward direction, and the REV signal is output when instructing rotation in the reverse direction. Furthermore, MPU5 is USM
When outputting the ON signal instructing the driving of 21, the control signal is output to the pulse width setting circuit 16 so as to gradually widen the pulse width for a fixed time. Also, USM
Even when 21 is stopped, the control signal is output so that the pulse width is gradually narrowed for a fixed time.
The control of the pulse width of the pulse width setting circuit 16 at the time of starting and stopping the driving of the USM 21 will be described later in detail.

When the change-over switch 18 receives the ON signal and the signal instructing the rotation direction from the MPU 5, the combination of the four output signals of the ring counter 17 is changed based on the ON signal and the signal is output to the drive circuit 19. MPU
5, when the rotation in the forward direction is instructed, the changeover switch 18 changes the output signals A ₁ and B ₁ of the ring counter 17 to C and D and A ₂ and B ₂ to E and F as shown in FIG. Output as. In addition, when it is instructed to rotate in the opposite direction, FIG.
As shown in, the output signals A ₂ , B of the ring counter 17
₂ is output as C, D, A ₁ and B ₁ are output as E and F. As a result, in the drive circuit 19, the phase of 90 is determined based on the signals C, D and E, F of the output signal of the changeover switch 18.
Two sinusoidal drive signals that are deviated from each other are generated and applied to the terminals G and H of the USM 21 via the booster coil 20, respectively. For example, in the case of positive rotation, USM21
When a sinusoidal drive signal whose phase is 90 degrees ahead of that of the H terminal is applied to the G terminal of the
A sinusoidal drive signal whose phase is advanced by 90 degrees is applied to the H terminal with respect to the G terminal.

On the other hand, when the driving of the USM 21 is instructed as described above, and at the same time when the MPU 5 outputs a control signal to the pulse width setting circuit 16 so as to gradually widen the pulse width for a fixed time, the pulse width setting circuit 16 is shown in FIG.
As shown in (c), the pulse width of the output signal fd having a constant frequency of the VCO 15 is gradually expanded and output as T ₁ , T ₂ , T ₃ , T ₄ . Here, when the pulse width is gradually widened and output as shown in FIG. 5C, the amplitude of the drive voltage output from the drive circuit 19 gradually increases accordingly, and the rotation speed of the USM 21 accordingly. And gradually accelerate. FIG. 6 is a diagram showing the drive characteristics of the USM21. The horizontal axis represents the drive frequency of the USM 21, the vertical axis represents the rotation speed, and the characteristics when the drive voltage amplitude is changed are shown. The drive frequency f is constant here. Now, when the amplitude of the driving voltage is gradually changed from the smaller one to the larger one at the driving frequency f = p, the rotation speed of the USM 21 gradually increases as shown in FIG.

In this way, the USM 21 starts rotating in the instructed direction, and by this drive, the shuttle on which the optical card is placed also starts moving. Further, the objective lens 9 also moves toward the center of the optical head following the movement of the shuttle by the action of the tracking servo. When a predetermined time has elapsed from the start of driving the USM 21, the operation of changing the pulse width of the pulse width setting circuit 16 as described above is stopped by the instruction of the MPU 5, and the output signal of the pulse width setting circuit 16 is as shown in FIG. It is restored to the original signal with the same pulse width as shown. Therefore, after that, the USM 21 is driven based on the output signal of the normal pulse width setting circuit 16, and the shuttle continues to move toward the center of the optical head. When the lens position sensor 11 detects that the objective lens 9 has moved near the center of the optical head along with the movement of the shuttle, the MPU 5 causes the pulse width setting circuit 16 to move.
A control signal is output so as to gradually narrow the pulse width.

The pulse width setting circuit 16 outputs an output signal by the control signal so that the pulse width gradually narrows, as shown in FIG. The amplitude of the drive voltage is controlled so as to gradually decrease. When the amplitude of the driving voltage is gradually decreased in this way, as is clear from FIG.
The rotation speed of M21 is gradually reduced accordingly.
Then, after a predetermined time has elapsed from the start of deceleration, the objective lens 9
When reaches the center of the optical head, the MPU 5 outputs an OFF signal for instructing the drive switch 18 to stop driving the USM 21, and the drive of the USM 21 is completely stopped. In this way, the objective lens 9 returns to the center of the optical head, and thereafter, tracking control is performed by similarly slightly moving the objective lens 9 in the tracking direction by the tracking servo, and information is recorded or reproduced on the information track.

In this embodiment, when the driving of the USM 21 is started, the pulse width of the pulse width setting circuit 16 is gradually widened so that the drive voltage amplitude of the USM 21 can be gradually increased, and the rotation of the USM 21 is rotated. The speed can be gradually increased. Further, when the driving of the USM 21 is stopped, the drive voltage amplitude of the USM 21 can be gradually reduced by gradually narrowing the pulse width of the pulse width setting circuit 16, and the rotation speed of the USM 21 can be gradually reduced. . Therefore, when the shuttle is moved by using the USM21, the USM21 has excellent response characteristics, and acceleration is large due to the good response characteristics at the time of starting and stopping the driving. As described above, the driving voltage at the time of starting the driving of the USM21 is as follows. By gradually increasing and gradually decreasing when stopped, it is possible to suppress sudden acceleration and deceleration of the shuttle.
It is possible to prevent an increase in the T error amount.

FIG. 7 is a diagram showing a comparison between the AT error amount when the USM 21 is driven and when the USM 21 is driven, in the prior art and the present embodiment. FIG. 7A shows the conventional AT error amount, and FIG. 7B shows the AT error amount of this embodiment. In addition, the drive signal is the same as that of FIG.
The signal output from the PU 5 to the changeover switch 18 to drive and stop the USM 21, and the pulse width is the pulse width of the output signal of the pulse width setting circuit 16. Conventionally, FIG. 7 (a)
When the drive signal is turned on as shown in, the pulse width is constant and the AT error amount increases due to the rapid acceleration of the shuttle when the USM21 starts to drive, and the number of the AT start when the USM21 starts to stop due to the rapid deceleration of the shuttle. The AT error amount also doubles. On the other hand, in the present embodiment, FIG.
When the drive signal is turned on, the pulse width is gradually widened, and when it is turned off, the pulse width is gradually narrowed, which gradually increases or decreases the drive voltage amplitude, so the shuttle should be gradually accelerated or decelerated. Therefore, the AT error amount can be significantly reduced as compared with the conventional case. Therefore, A
Since the T error amount can be reduced, it is possible to solve the problem that the AT is out of place as in the conventional case, and to stabilize the operation of the apparatus.

In the above embodiment, the USM drive voltage amplitude is gradually increased or decreased by gradually widening or narrowing the pulse width of the output signal of the pulse width setting circuit. The drive voltage amplitude can also be gradually increased or decreased by increasing or decreasing the pulse height of the signals C, D, E, F output from the drive circuit to the drive circuit.

FIG. 8 is a block diagram showing another embodiment of the present invention. In FIG. 8, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, U
USM2 when the drive of SM21 is started (when the drive signal is on)
By gradually increasing the drive frequency of No. 1 and gradually decreasing the drive frequency when the drive is stopped (when the drive signal is off), rapid acceleration and rapid deceleration of the shuttle are suppressed. The drive frequency of the USM 21 is controlled by the input voltage supplied from the MPU 5 to the VCO 15 via the D / A converter 14, and its specific control operation will be described later in detail. In addition, in FIG.
Since it is not necessary to change the pulse width of O15, the pulse width setting circuit 16 is not provided and the VCO 15 outputs a signal directly to the ring counter 17. Other configurations are the same as those in FIG.

Next, the specific operation of the above embodiment will be described. First, it is assumed that information is recorded or reproduced on an optical card having a skew as in the embodiment of FIG.
It is assumed that the objective lens 9 has moved near the limit of either the left or right movable range during scanning on the information track. Similarly, the movable range of the objective lens 9 is ± 25 μm. The position of the objective lens 9 is monitored by the lens position sensor 11, and when the MPU 5 recognizes that the objective lens 9 is near the limit of the movable range from the detection signal of the lens position sensor 11, the changeover switch 18 of the USM 21 A signal indicating the rotation direction of the USM 21 is output based on the ON signal for starting driving and the detection signal of the lens position sensor 11. At the same time, a control signal is output from the MPU 5 to the VCO 15 via the D / A converter 14 so as to gradually lower the drive frequency of the USM 21 for a predetermined time. The specific operation is as follows.

First, FIG. 9 shows the drive frequency of the USM21,
It is a characteristic view showing the relationship of rotation speed. Here, it is assumed that the drive frequency is used in the L region (low frequency region) with the resonance point as a boundary. When the MPU 5 outputs an ON signal to instruct to drive the USM 21, a signal is output to the D / A converter 14 so as to gradually increase the input voltage of the VCO 15 for a predetermined time, and as a result, as shown in FIG. The drive frequency gradually increases from p to q for a predetermined time. As a result, at the start of driving the USM21,
The rotation speed of the USM 21 gradually increases, and the shuttle gradually accelerates without sudden acceleration. After a lapse of a predetermined time, the drive frequency is fixed at q, and the shuttle continues to move in this state. Then, the lens position sensor 11
When it is detected that the objective lens 9 has moved near the center of the optical head, the MPU 5 causes the D / A converter 14 to
Then, a signal is output so as to gradually lower the input voltage of the VCO 15 for a predetermined time. As a result, the drive frequency of the USM21 gradually decreases from q to p, and U
Since the rotation speed of the SM 21 gradually decreases, the shuttle gradually decelerates. When the predetermined time has passed, the MPU
An OFF signal is output from 5, and the driving of the USM 21 is stopped. On the contrary, in the case of H (high frequency region), the same control can be performed by gradually decreasing the frequency during acceleration and gradually increasing the frequency during deceleration.

In the present embodiment, the drive frequency is gradually approached to the resonance frequency when the USM 21 starts to drive, and is gradually moved away from the resonance frequency when the drive is stopped. Therefore, just like the embodiment of FIG. Acceleration and rapid deceleration can be suppressed, and an increase in AT error amount can be prevented. FIG. 10 is a diagram showing a comparison between the AT error amount when the drive signal is ON and OFF in the conventional example, and FIG. 10A is a conventional AT error amount, and FIG. 10B is the AT error amount of the present example. is there.
The area (a) in FIG. 10 (b) is an acceleration area where the drive frequency of the USM 21 gradually approaches the resonance frequency, (b) is a constant speed area where the drive frequency is constant, and (c) is a deceleration area where the drive frequency is gradually moved away from the resonance frequency. Is. Conventionally, FIG. 10 (a)
The AT error amount increases when the drive signal is turned on or off as shown in FIG.
As shown in (b), the AT error amount when the drive signal is turned on and off can be significantly reduced as compared with the conventional case.

Although the drive frequency is changed by changing the input voltage of the VCO 15 in the above embodiments, the present invention is not limited to this. For example, the pulse signal of the VCO 15 is divided and the division ratio is USM21. It is also possible to gradually change the drive frequency by gradually changing the drive frequency when starting and stopping.

Next, still another embodiment of the present invention will be described. In the embodiment of FIG. 1 and FIG. 8, the sudden acceleration or deceleration of the shuttle is suppressed by changing the drive voltage amplitude or the drive frequency when the USM 21 is started or stopped.
In this embodiment, the ON signal and the OFF signal from the MPU 5 are intermittently output to gradually increase or gradually decrease the rotation speed of the USM 21. MPU5
As described above, the MPU5 of FIG.
The OFF signal is a signal instructing to stop driving, and the OFF signal is a signal instructing to stop driving.

When the lens position sensor 11 of FIG. 8 detects that the objective lens 9 has moved to the limit of the movable range, the MPU 5 instructs the changeover switch 18 to start driving the USM 21. Is output. Of course, a signal indicating the rotation direction of the USM 21 is also output. Further, at this time, a constant input voltage is applied from the MPU 5 to the VCO 15 in FIG. 8, and the drive frequency is constant. The ON signal is intermittently output as shown in FIG. 11A, the duty ratios of the ON and OFF signals remain the same at about 50%, and the cycles are T ₁ , T ₂ ,
It is output so that it becomes gradually longer, such as T ₃ . Due to this intermittent ON signal, the USM 21 is alternately driven and stopped, and the driving time during the ON period gradually increases, so that the rotation speed of the USM 21 gradually increases. It is gradually accelerated. The intermittent ON signal becomes a normal high level ON signal only for a predetermined time.

In this way, the shuttle is gradually accelerated, and when the objective lens 9 comes close to the center of the optical head, this time the MPU
5 outputs an intermittent off signal as shown in FIG. 11 (b). Contrary to the above, the OFF signal has a period of T ₁ , T
_It is output so that it becomes gradually shorter, such as ₂ and T ₃ ,
At this time, the driving time of the USM 21 is gradually shortened, so that the rotation speed is gradually reduced and the shuttle is gradually decelerated. Then, after a lapse of a predetermined time, the OFF signal becomes a normal low level signal, and the driving of the USM 21 is stopped.

In this embodiment, an ON signal and an OFF signal are intermittently output at the time of starting and stopping the driving of the USM 21, and the driving time is gradually lengthened at the start of driving so that the driving time is stopped at the time of stopping. Since the on / off signals are output so as to be gradually shortened, the sudden acceleration and deceleration of the shuttle can be suppressed in exactly the same manner as in the embodiments of FIGS. 1 and 8. FIG. 12 shows the drive signal and A in the conventional example and the present example.
In the diagram showing the comparison of the T error amount, the AT error amount can be significantly reduced as shown in FIG. 12B in the present embodiment as compared with the conventional case of FIG. 12A.

In the embodiment, the duty ratios of the ON and OFF signals are kept at about 50%, but the duty ratio may be set arbitrarily. Further, the rate of increase or decrease of the rotation speed of the USM 21 is determined by the rate of increase or decrease of the cycle of the ON or OFF signal. Therefore, the rate of increase or decrease of the cycle of the ON or OFF signal should be set to an optimum value in advance. It is desirable to put it. Furthermore, in the above three embodiments, the shuttle was moved in the cross-track direction, but the shuttle may be fixed in the cross-track direction and the optical head may be moved in the cross-track direction. In this case, the USM 21 may be controlled at the start and stop of driving the optical head in the same manner as in the above embodiment.

[0037]

As described above, the present invention suppresses sudden acceleration or deceleration of the shuttle or the optical head by gradually increasing the driving speed when starting the driving of the driving means and gradually decreasing it when the driving is stopped. can do. Therefore, it is possible to prevent the tracking error amount from increasing at the time of starting and stopping the driving of the driving unit, and thus there is an advantage that the problem such as tracking error is eliminated and the operation of the apparatus can be stabilized.

[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.

FIG. 3 is a time chart showing an output signal of a changeover switch when the USM of the embodiment of FIG. 1 operates in a forward direction.

FIG. 4 is a time chart showing the output signal of the changeover switch when the USM of the embodiment of FIG. 1 is rotated in the reverse direction.

5 is a diagram illustrating a pulse width setting circuit according to the embodiment of FIG.
7 is a time chart showing output signals at the start and stop of driving of the SM.

6 is a characteristic diagram showing the relationship between the drive frequency and the rotation speed when the drive voltage amplitude of the USM of the embodiment of FIG. 1 is changed.

7 is a diagram showing a comparison between the pulse width and the AT error amount of the pulse width setting circuit in the conventional example and the embodiment of FIG.

FIG. 8 is a block diagram showing another embodiment of the present invention.

9 is a diagram showing the relationship between the USM drive frequency and the rotation speed of the embodiment of FIG.

FIG. 10 is a diagram showing a comparison of AT error amounts between the conventional example and the example of FIG.

FIG. 11 is a diagram illustrating another embodiment of the present invention, in which the USM starts driving and the MPU starts driving when the USM starts driving.
6 is a time chart showing ON signals and OFF signals output as signals for instructing stop.

FIG. 12 is a diagram showing a comparison between an ON signal instructing to drive a USM and an AT error amount in the related art and the embodiment of FIG. 11.

FIG. 13 is a schematic configuration diagram showing a conventional optical card information recording / reproducing apparatus.

FIG. 14 is a diagram showing skew of an optical card.

[Explanation of symbols]

 1 Photodetector 2, 3 Differential Amplifier 5 MPU 6 Phase Compensator 7 AT Coil Driver 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 motor (USM)

Claims (5)

[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, a driving means for moving either a shuttle for mounting the recording medium or an optical head in a transverse direction of an information track, and driving of the driving means. A control means for controlling the driving speed of the driving means at the start and stop of driving is provided, and when the light beam of the optical head is scanned on the information track, the driving means causes the shuttle or the optical head to cross the track. By correcting the positional relationship between the light beam and the information track by moving the driving means in the direction, the driving speed of the driving means is gradually increased by the control means when the driving means is started, and is gradually decreased when the driving is stopped, An optical information recording / reproducing apparatus characterized in that the shuttle or the optical head is gradually accelerated or decelerated. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the driving means is an ultrasonic motor. 3. The control means gradually increases the drive voltage amplitude when the drive means starts driving, and gradually lowers the drive voltage amplitude when the drive is stopped, thereby gradually accelerating the shuttle or the optical head. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording / reproducing apparatus is decelerated. 4. The control means gradually brings the drive frequency closer to the resonance frequency when the drive means starts driving, and gradually moves the drive frequency away from the resonance frequency when the driving is stopped, thereby gradually moving the shuttle or the optical head. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording / reproducing apparatus accelerates or decelerates. 5. The control means intermittently outputs an ON signal for instructing the start of the driving means at the start of driving of the driving means so that the ON time gradually increases.
When the driving is stopped, an OFF signal for instructing the stop of the driving unit is intermittently output so that the OFF time is gradually shortened, whereby the shuttle or the optical head is gradually accelerated or decelerated. Claim 1
Optical information recording and reproducing device.