JP3273278B2 - Optical information recording / reproducing device - Google Patents

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 and reproducing information on a card-shaped recording medium.

[0002]

2. Description of the Related Art Various types of recording media, such as a disc and a card, are conventionally known as a recording medium for optically recording information or optically reading recorded information. Among these information recording media, card-shaped recording media (hereinafter, referred to as optical cards) are small, lightweight, portable, and have 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, a light beam modulated according to the recorded information and focused on a minute light spot is optically detected by scanning an information track. Information is recorded as possible recording pit strings. When recording this information,
In order to record information accurately without causing troubles such as intersection with information tracks, the irradiation position of the light beam is controlled in the transverse direction of the track, and auto tracking is performed so that the light beam scans following the information track Control is performed. Of course, the auto-tracking control is also performed at the time of reproducing the information, and the light beam is controlled to scan following the information track.

FIG. 13 is a block diagram showing an example of an optical card recording and reproducing apparatus for recording and reproducing information on the optical card. In the figure, 100 is an optical card as an information recording medium, 10
Reference numeral 1 denotes a shuttle on which the optical card 100 is placed. The shuttle 101 is configured to be able to move in the cross-track direction by driving an ultrasonic motor (hereinafter, abbreviated as USM) 103. The shuttle 101 moves the light beam in the cross-track direction under the control of the USM control circuit 104, and will be described later. The correction control for the skew of the optical card 100 is performed in such a manner. Reference numeral 105 denotes a semiconductor laser as a light source for recording and reproduction, and reference numeral 106 denotes a collimator lens for collimating the light beam of the semiconductor laser 105.

The light beam from the semiconductor laser 105 is incident on an objective lens 108 via a collimator lens 106 and a polarizing beam splitter 107, where it is focused on a minute light spot and irradiated on an optical card 100. The irradiation light is reflected on the surface of the optical card 100, and the reflected light is again converted into parallel light through the objective lens 108, and further transmitted through the polarization beam splitter 107 and guided to the polarization beam splitter 109. Then, the light is reflected by the polarization beam splitter 109, collected by the condenser lens 110, and received by the photoelectric conversion element 111 for tracking control.
The 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 able to reciprocate 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 reciprocate relatively, 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 receiving signal of the photoelectric conversion element 111 is input to a tracking control circuit 112, and the tracking control circuit 112 generates a tracking error signal indicating the amount of deviation of the light beam from the track and the direction of the deviation based on the received light signal. You. Then, the tracking control circuit 112
By driving the tracking actuator 113 based on the tracking error signal and moving the objective lens 108 minutely in the cross-track direction, tracking control is performed so that the light beam does not deviate from the information track during scanning of the light beam as described above. Is performed. In this way, the tracking of the light beam is controlled, and the recording or reproduction of information is performed with the tracking control applied when recording or reproducing information.

Here, the information track of the optical card 100 is not parallel to the track direction as shown in FIG. 14, but may have a skew angle θ slightly inclined. When an optical card having such a skew is scanned with a light beam under tracking control, the objective lens 108
Has a limit in its movable range, the light beam may fall 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 optical card 100 is moved in the cross-track direction by the USM 103 to perform the skew correction control. Specifically, first, the objective lens 10
Assume that the movable range of 8 is, for example, 25 μm to the left and right from the lens center position, and that 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 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
25μm which is movable range from left to right from the center position
Is moved, the tracking control circuit 112 sends the USM
A control signal is output to the control circuit 104 to move the shuttle 101 to 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 cross-track direction. In this state, the tracking control is working, so that the objective lens 108 also follows the shuttle 101 and moves toward the center of the optical head 102. Go to in this case,
In order to drive the USM 103, the USM control circuit 104 outputs a two-phase sine wave drive signal whose phase is shifted by 90 degrees. Then, the objective lens 108 is
When the objective lens 108 is positioned at the center of the movable range and is located at the center of the movable range, the tracking control circuit 112 outputs a control signal to the USM control circuit 104 to stop the shuttle 101. If the optical card 100 is skewed in this way, by moving the shuttle 101, the objective lens 108 is controlled to return to the center of the optical head 102, and correction control of the positional relationship between the light beam and the information track is performed. Will be

[0009]

However, in the above-mentioned conventional information recording / reproducing apparatus, the USM is used as a driving means for moving the shuttle in the cross-track direction. When the USM is used, the shuttle is suddenly accelerated at the start of driving of the USM, and suddenly decelerated at the stop of driving. Therefore, a tracking error amount (AT error amount) increases at the time of starting and stopping the drive of the USM, and there is a problem that if the AT error amount is too large, AT departure occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to suppress the sudden acceleration and rapid deceleration of the shuttle so as to prevent an increase in the AT error amount, thereby stabilizing the operation. An object of the present invention is to provide an information recording / reproducing device.

[0011]

An object of the present invention is to provide an optical head.
Optical beam through an objective lens
In the optical information recording and reproducing apparatus for recording or reproducing information by irradiating the information track of the upper, the
Move the objective lens slightly in the transverse direction of the information track.
The light beam with respect to the information track.
Means for performing tracking control, and the objective lens
Said optical head or recording medium to return to the center of the movement range
One of the shuttles carrying the information truck
An ultrasonic motor for moving in the transverse direction of the
Means for controlling the driving speed of the motor.
Is to gradually increase the driving speed of the ultrasonic motor at the start of driving and gradually decrease the driving speed at the stop of driving.
The optical information recording / reproducing apparatus is characterized in that the optical head or shuttle is gradually accelerated or decelerated.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the optical information recording / reproducing apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a photodetector for detecting reflected lights of two tracking control light spots 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 side beams of these are used for tracking control by an optical card. Irradiation is performed on two tracking tracks provided on both sides of the information track. The photodetector 1 includes detection pieces 1a and 1b corresponding to two light spots, and the reflected light of the two light spots reflected from the tracking track is 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 tracking error signals. The tracking error signal is binarized at a predetermined slice level by the comparator 10 and output to the MPU 5. The MPU 5 is a microprocessor circuit for controlling each part of the device.

Reference numeral 3 denotes a differential amplifier to which a predetermined voltage is input from the MPU 5 via the D / A converter 4 when performing a track jump by the objective lens 9. However, at the time of a track jump, the tracking servo loop is turned off by a switch (not shown). 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,
The MPU 5 controls the light beam to be drawn again to the target information track at the zero cross point based on the input signal. 6 is a phase compensator for stabilizing the tracking servo loop, 7 is a tracking actuator coil (AT coil) 8 which amplifies the power of the tracking error signal.
An AT coil driver 9 for driving the laser beam; and an objective lens 9 for condensing a light beam of a semiconductor laser as a light source and irradiating the light beam as a minute light spot on an optical card. The tracking error signal detected by the differential amplifier 2 is transmitted to the A through the differential amplifier 3, the phase compensator 6, and the AT coil driver 7.
The output is output to the T coil 8, the AT coil 8 is driven by a tracking error signal, and the objective lens 9 is slightly moved in the tracking direction, so that tracking control for scanning the light spot following the information track is performed.

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. A reflecting plate (not shown) is attached to the side of the lens barrel of the objective lens 9 so as to face the lens position sensor 11. The reflector is irradiated with light from a light emitting element (not shown), and the reflected light is applied to the two light receiving elements 1 of the position sensor 11.
It is detected at 1a and 11b. In this case, the position sensor 11
Since the light receiving amounts of the light receiving elements 11a and 11b change according to the position of the objective lens 9 in the tracking direction, the differential amplifier 12 differentially detects the detection signals of the light receiving elements 11a and 11b. 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 denotes 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 in accordance with the input voltage, and outputs an 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, and 17 divides the output signal fw of the pulse width setting circuit 16 by 4 and converts the divided signal. This 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 for output. 18 is US output from MPU5
ON to instruct whether to drive or stop M21
/ OFF drive signal and USM21 are rotated forward,
This is a changeover switch for selectively outputting the output signal of the ring counter 17 based on the FWD / REV signal indicating whether to rotate in the reverse direction or the rotation direction. Reference numeral 19 denotes a drive circuit for power-amplifying the output of the changeover switch 18, reference numeral 20 denotes a booster circuit for boosting the output of the drive circuit 19,
Reference numeral 1 denotes a USM for moving the shuttle 101 on which the optical card 100 is placed in the cross-track direction as described with reference to FIG.

Next, a specific operation of the above embodiment will be described. First, when 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 reciprocate relatively. At this time, the photodetector 1 of FIG.
It is assumed that the tracking servo loop from 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 following 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 applied 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. 14, and when tracking control is performed by a 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 is taken into the MPU 5 by the A / D converter 13. That is, the MPU 5 monitors the position of the objective lens 9, and
As described above, the objective lens 9 moves according to the skew,
When the objective lens 9 moves closer to the limit of the movable range, the USM 21 is driven to move the shuttle on which the optical card is mounted in the tracking direction, thereby controlling the objective lens 9 to return to the center of the optical head. .

The control operation of the USM 21 will now be described. First, FIG. 2 is a time chart showing signals of various parts of the control circuit for controlling the driving of the USM 21.
2A shows the output signal of the VCO 15, and FIG. 2B shows the output signal of the pulse width setting circuit 16. During operation of the device, 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. Is output.
A control signal for instructing a pulse width is output from the MPU 5 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 the designated pulse width is output as shown in FIG. The ring counter 17 divides this pulse signal by four and separates the divided signal into four sets of signals whose phases are shifted by 90 degrees as shown in FIGS. 2C to 2F. 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 an ON / OFF drive signal instructing driving from the MPU 5 and a FWD / REV signal instructing the rotation direction. MP in the state where the normal USM21 is not driven
An off signal is output from U5 to the changeover switch 18, the changeover switch 18 does not output a signal to the drive circuit 19 according to this instruction, and the USM 21 is kept in a stopped state.

Here, in the MPU 5, as described above, the objective lens 9 is moved to the left or right in the tracking direction by the output of the lens position sensor 11 so that the movable range is limited to 25 μm.
m is recognized, the changeover switch 18
To output an ON signal for instructing the drive of the USM 21. 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
A signal for instructing the rotation direction of the SM 21 is set to a switch 18
Output to In FIG. 1, the 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 uses USM
When outputting an ON signal instructing the driving of the control signal 21, a control signal is output to the pulse width setting circuit 16 so as to gradually increase the pulse width for a predetermined time. USM
Also when the control signal 21 is stopped, a control signal is output so as to gradually narrow the pulse width for a certain 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 changeover switch 18 receives the ON signal and the signal indicating 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
If 5 is instructed to rotate in the forward direction, the changeover switch 18 to A _1, B ₁ of the output signal of the ring counter 17 as shown in FIG. _{3 C, D, A 2,} B 2, and E, F Output as Also, when the user is instructed to rotate in the reverse direction, FIG.
A _2, the output signal of the ring counter 17 as shown in B
₂ is output as C, D, A ₁ , B ₁ , and E, F. As a result, the drive circuit 19 has a phase of 90 based on the output signals C, D and E, F of the changeover switch 18.
Two sine-wave-like drive signals shifted by degrees are generated and applied to the terminals G and H of the USM 21 via the boosting coil 20 respectively. For example, in the case of forward rotation, USM21
In the case of the G terminal, a sinusoidal drive signal whose phase is advanced by 90 degrees than the H terminal is applied, and conversely, in the case of rotation in the opposite direction,
A sine-wave-like drive signal whose phase is advanced by 90 degrees from the G terminal to the G terminal is applied.

On the other hand, when the control signal is output from the MPU 5 to the pulse width setting circuit 16 so as to gradually widen the pulse width by a certain time at the same time as instructing the driving of the USM 21 as described above, the pulse width setting circuit In FIG. 5, FIG.
As shown in (c), the pulse width of the output signal fd of the constant frequency of the VCO 15 is output in a stepwise manner such as T ₁ , T ₂ , T ₃ , T ₄ . Here, when the pulse width is gradually widened and output as shown in FIG. 5 (c), the amplitude of the drive voltage output from the drive circuit 19 gradually increases accordingly, and the rotational speed of the USM 21 also changes accordingly. And gradually accelerate. FIG. 6 is a diagram showing the driving characteristics of the USM 21. The horizontal axis indicates the drive frequency of the USM 21, and the vertical axis indicates the rotation speed, and shows the characteristics when the drive voltage amplitude is changed. The drive frequency f is constant here. Now, when the amplitude of the drive voltage is gradually changed from the smaller one to the larger one at the drive frequency f = p, the rotational speed of the USM 21 gradually increases as shown in FIG.

Thus, the USM 21 starts rotating in the specified direction, and the shuttle on which the optical card is placed also starts moving by this drive. The objective lens 9 also moves toward the center of the optical head by following the movement of the shuttle by the function of the tracking servo. When a predetermined time has elapsed from the start of driving of the USM 21, the operation of changing the pulse width of the pulse width setting circuit 16 described above is stopped by the instruction of the MPU 5, and the output signal of the pulse width setting circuit 16 becomes as shown in FIG. As shown, the signal is returned to the original signal of the same pulse width. Therefore, thereafter, the USM 21 is driven based on the output signal of the ordinary 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 with the movement of the shuttle, the MPU 5 sends a pulse width setting circuit 16
, A control signal is output so as to gradually narrow the pulse width.

In the pulse width setting circuit 16, an output signal is output by the control signal so that the pulse width is gradually narrowed, as shown in FIG. Is controlled so that the amplitude of the driving voltage gradually decreases. When the amplitude of the drive voltage is gradually reduced in this manner, as is apparent from FIG.
The rotation speed of M21 gradually decreases accordingly.
Then, a predetermined time has elapsed from the start of deceleration, and the objective lens 9
Reaches the center of the optical head, the MPU 5 outputs an OFF signal instructing the changeover switch 18 to stop driving the USM 21, and the driving of the USM 21 is completely stopped. In this way, the objective lens 9 returns to the center of the optical head, and thereafter, the tracking control is performed by similarly moving the objective lens 9 minutely in the tracking direction by the tracking servo, thereby recording and reproducing information on the information track.

In this embodiment, when the drive of the USM 21 is started, the pulse width of the pulse width setting circuit 16 is gradually increased, so that the drive voltage amplitude of the USM 21 can be gradually increased, and the rotation of the USM 21 can be increased. Speed can be accelerated gradually. When the drive of the USM 21 is stopped, by gradually narrowing the pulse width of the pulse width setting circuit 16, the drive voltage amplitude of the USM 21 can be gradually reduced, and the rotational 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 the acceleration increases due to the good response characteristics at the start and stop of the drive. Is gradually increased, and is gradually reduced when stopped, so that rapid acceleration and deceleration of the shuttle can be suppressed.
An increase in the T error amount can be prevented.

FIG. 7 is a diagram showing a comparison between the AT error amount when the USM 21 is driven and the AT error amount when the USM 21 is stopped in the prior art and this embodiment. FIG. 7A shows the AT error amount in the related art, and FIG. 7B shows the AT error amount in the present embodiment. Further, as described above, the drive signal is M
The signal output from the PU 5 to the changeover switch 18 to instruct driving and stopping of the USM 21 and the pulse width are the pulse widths of the output signal of the pulse width setting circuit 16. Conventionally, FIG.
When the drive signal is turned on as shown in (1), the pulse width is constant. The AT error amount increases twice as much. 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 off, the pulse width is gradually narrowed, which gradually increases or decreases the drive voltage amplitude, so that the shuttle is gradually accelerated or decelerated. Thus, the AT error amount can be greatly reduced as compared with the related art. Therefore, A
Since the T error amount can be reduced, it is possible to solve the problem that the AT deviates as in the related art, and to stabilize the operation of the device.

In the above embodiment, the drive voltage amplitude of the USM is gradually increased or decreased by gradually increasing or decreasing 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 controller 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 denoted by the same reference numerals, and description thereof will be omitted. This embodiment is based on U
When the drive of SM21 is started (when the drive signal is turned on), USM2
1 is to gradually increase the drive frequency, and when the drive is stopped (when the drive signal is off), the drive frequency is gradually decreased, thereby suppressing rapid acceleration and sudden deceleration of the shuttle. The drive frequency of the USM 21 is controlled by an input voltage supplied from the MPU 5 to the VCO 15 via the D / A converter 14, and a specific control operation thereof will be described later in detail. In FIG. 8, VC
Since it is not necessary to change the pulse width of O15, the pulse width setting circuit 16 is not provided, and a signal is directly output from the VCO 15 to the ring counter 17. Other configurations are the same as those in FIG.

Next, a 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 similarly to the embodiment of FIG.
It is assumed that the objective lens 9 has moved near the limit of the movable range of either the left or the right during the scanning of the information track. The movable range of the objective lens 9 is also ± 25 μm. The position of the objective lens 9 is monitored by the lens position sensor 11. When the MPU 5 recognizes that the objective lens 9 is near the limit of the movable range based on the detection signal of the lens position sensor 11, the MUS 5 switches the USM 21 to the changeover switch 18. Based on the ON signal for starting the driving and the detection signal of the lens position sensor 11, a signal indicating the rotational direction of the USM 21 is output. 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 driving frequency of the USM 21 and
FIG. 4 is a characteristic diagram illustrating a relationship between rotation speeds. Here, it is assumed that the driving 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 the driving of 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. 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 USM 21,
The rotation speed of the USM 21 gradually increases, and the shuttle is gradually accelerated without sudden acceleration. After a lapse of a predetermined time, the drive frequency is fixed at q, and the shuttle keeps moving in this state. Then, the lens position sensor 11
Detects that the objective lens 9 has moved near the center of the optical head by the MPU 5, the D / A converter 14
A signal is output such that the input voltage of the VCO 15 is gradually lowered for a predetermined time. As a result, the drive frequency of the USM 21 gradually decreases from q to p, and the
Since the rotation speed of the SM 21 gradually decreases, the shuttle gradually decelerates. After a predetermined time, the MPU
5 outputs an off signal, and the driving of the USM 21 is stopped. Conversely, in the case of H (high frequency range), the same control can be performed by gradually lowering the frequency during acceleration and gradually increasing the frequency during deceleration.

In this embodiment, the drive frequency is controlled so as to gradually approach the resonance frequency when the drive of the USM 21 is started, and is gradually moved away from the resonance frequency when the drive is stopped. Acceleration and sudden deceleration can be suppressed, and an increase in the AT error amount can be prevented. FIG. 10 is a diagram showing a comparison between the AT error amount when the drive signal is turned on and the drive signal is turned off in the present embodiment. FIG. 10A shows the conventional AT error amount, and FIG. is there.
10B is an acceleration region where the drive frequency of the USM 21 gradually approaches the resonance frequency, B is a constant speed region where the drive frequency is constant, and C is a deceleration region where the drive frequency gradually moves away from the resonance frequency. It is. Conventionally, FIG.
The AT error amount increases when the drive signal is turned on or off as shown in FIG.
As shown in (b), the amount of AT error when the drive signal is turned on and off can be greatly reduced as compared with the conventional case.

In the above embodiment, the drive frequency is changed by changing the input voltage of the VCO 15. However, the present invention is not limited to this. For example, the frequency of the pulse signal of the VCO 15 is It is also possible to gradually change the drive frequency by gradually changing at the start and stop of the drive.

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

Here, when the lens position sensor 11 shown in FIG. 8 detects that the objective lens 9 has moved near the limit of the movable range, the MPU 5 instructs the changeover switch 18 to start driving the USM 21 to the ON signal. Is output. Of course, a signal indicating the rotational direction of the USM 21 is also output. At this time, a constant input voltage is applied from the MPU 5 to the VCO 15 in FIG. 8, and the driving frequency is constant. The ON signal is outputted intermittently as shown in FIG. 11A, and the duty ratio of the ON and OFF signals remains the same at approximately 50%, and the periods are T ₁ , T ₂ ,
It is output so as to gradually become longer and so on T _3. The intermittent ON signal causes the USM 21 to alternately drive and stop, and the drive time during the ON period gradually increases, so that the rotation speed of the USM 21 gradually increases, and the shuttle It is gradually accelerated. The intermittent ON signal is only for a predetermined time, and thereafter becomes a normal high-level ON signal.

Thus, the shuttle is gradually accelerated, and when the objective lens 9 comes near the center of the optical head, the MPU
5 outputs an intermittent off signal as shown in FIG. The OFF signal has a cycle of T ₁ , T
₂ , T ₃ , etc. are output so as to be gradually shorter,
At this time, since the driving time of the USM 21 gradually decreases, the rotation speed gradually decreases, and the shuttle gradually decelerates. When the predetermined time has elapsed, the off signal becomes a normal low level signal, and the driving of the USM 21 is stopped.

In this embodiment, when the drive of the USM 21 is started and stopped, the ON signal and the OFF signal are output intermittently, and the drive time is gradually increased at the start of drive, and the drive time is set at the stop of drive. Since the ON and OFF signals are output so as to be gradually shortened, it is possible to suppress sudden acceleration and sudden deceleration of the shuttle just like in the embodiment of FIGS. FIG. 12 shows the driving signal and A in the related art and this embodiment.
FIG. 12A is a diagram showing a comparison of the T error amount. In the present embodiment, the AT error amount can be significantly reduced as shown in FIG.

In the embodiment, the duty ratio of the on / off signal is kept at approximately 50%, but the duty ratio may be set arbitrarily. Further, the rate of increase or decrease of the rotational speed of the USM 21 is determined by the rate of increase or decrease of the cycle of the ON / OFF signal. It is desirable to keep. Further, in the above three embodiments, the shuttle is moved in the cross-track direction. However, 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 time of starting and stopping the driving of the optical head in the same manner as in the above embodiment.

[0037]

According to the present invention , as described above ,
At the start of driving the ultrasonic motor , gradually increase the driving speed,
When the driving is stopped, the speed is gradually lowered, so that the sudden acceleration or sudden deceleration of the shuttle or the optical head can be suppressed. Therefore, it is possible to prevent an increase in the tracking error amount at the time of starting or stopping the driving of the ultrasonic motor , so that there is no problem that tracking is lost, and the operation of the apparatus can be stabilized.

[Brief description of the drawings]

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

FIG. 2 is a time chart showing output signals of a VCO, a pulse width setting circuit, and a ring counter of the embodiment of FIG. 1;

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

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

FIG. 5 is a diagram showing a pulse width setting circuit according to the embodiment shown in FIG.
5 is a time chart showing output signals at the time of starting and stopping driving of an SM.

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

FIG. 7 is a diagram comparing a pulse width of a pulse width setting circuit with an AT error amount in the conventional example and the embodiment of FIG. 1;

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

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

FIG. 10 is a diagram showing a comparison of the AT error amount between the conventional example and the embodiment of FIG. 8;

FIG. 11 is a diagram illustrating still another embodiment of the present invention.
6 is a time chart showing an ON signal and an OFF signal output as signals for instructing stop.

FIG. 12 is a diagram showing a comparison between an ON signal for instructing USM driving and an AT error amount in the conventional example and the embodiment in FIG. 11;

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

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

[Explanation of symbols]

 DESCRIPTION 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 control oscillator (VCO) 16 Pulse width setting circuit 17 Ring counter 18 Changeover switch 19 Drive circuit 20 Step-up coil 21 Ultrasonic motor (USM)

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G11B 7/085 G11B 7/09 G11B 7/095

Claims (4)

(57) [Claims] 1. An optical information recording / reproducing apparatus which records or reproduces information by irradiating an information track on an optical information recording medium with a light beam via an objective lens of an optical head. A means for performing tracking control of the light beam on the information track by slightly moving the information track in a transverse direction, and a shuttle on which the optical head or a recording medium is mounted to return the objective lens to the center of a movable range. An ultrasonic motor for moving either one in the transverse direction of the information track, and means for controlling the driving speed of the ultrasonic motor, wherein the control means controls the driving speed of the ultrasonic motor at the start of driving. The optical head or shuttle is gradually accelerated or reduced by gradually raising it and gradually lowering it when the drive is stopped. An optical information recording / reproducing device characterized by speeding up. 2. The control unit gradually accelerates or decelerates the optical head or shuttle by gradually increasing a drive voltage amplitude at the start of driving of the ultrasonic motor and gradually decreasing the drive voltage amplitude at a stop of the drive. The optical information recording / reproducing apparatus according to claim 1, wherein: 3. The optical head according to claim 1, wherein the control unit gradually brings the drive frequency closer to the resonance frequency of the ultrasonic motor when starting the drive of the ultrasonic motor, and gradually moves away from the resonance frequency when the drive is stopped. 2. The optical information recording / reproducing apparatus according to claim 1, wherein the shuttle is gradually accelerated or decelerated. 4. The control means outputs an ON signal for driving the ultrasonic motor intermittently at the start of driving of the ultrasonic motor so that the ON time gradually increases, and when the driving is stopped, The ON signal is intermittently and ON
2. The optical information recording / reproducing apparatus according to claim 1, wherein the optical head or the shuttle is gradually accelerated or decelerated by outputting the time so as to be gradually shortened.
Equipment .