JP2815111B2 - Optical information recording / reproducing device - Google Patents

Description

The present invention relates to an optical information recording / reproducing apparatus, that is, an optical information recording apparatus that moves an optical spot relative to a track of an optical information recording medium while tracking the optical spot. The present invention relates to an optical information recording / reproducing apparatus capable of recording information on a recording medium and / or reproducing information recorded on an optical information recording medium.

2. Description of the Related Art Conventionally, various media such as a disk, a card, and a tape have been known as a medium for recording information using light and reading the recorded information. These optical information recording media include those capable of recording and reproduction and those capable of reproduction only.

Information recording on a recordable medium is performed by scanning an information track with a light beam modulated by recording information and focused on a minute spot, and information is recorded as an optically detectable information pit row. .

Further, in reproducing information from the recording medium, the information pit array of the information track is scanned with a light beam spot of such an output that recording is not performed on the recording medium, and reflected light or transmitted light from the recording medium is detected. This is done by:

For light beam spot irradiation on such a recording medium and detection of reflected light or transmitted light from the recording medium,
A so-called optical head is used. The optical head is relatively movable with respect to the recording medium in the information track direction and the direction crossing the track direction, and the information track scan of the light beam spot is performed by this relative movement.

Among such optical information recording media, a card-shaped optical information recording medium (hereinafter, referred to as an optical card) is expected to have a great demand as a relatively large-capacity information recording medium that is small, lightweight, and portable. Have been.

FIG. 6 is a schematic plan view of a write-once optical card, and FIG.
The figure is an enlarged view of the track portion.

In FIG. 6, on the information recording surface of the optical card C, a number of information tracks Ta extending in the LF direction are arranged in parallel. The information recording surface of the optical card C has an information track.
A home position HP is provided as a reference position for accessing Ta. Information Track Ta Home Position
There are two types: a recorded information track in which information is already recorded and an unrecorded information track in which no information is recorded, in which Ta1, Ta2, Ta3,...
Information can be recorded on this unrecorded information track at any time.

As shown in FIG. 7, a tracking track Tb is provided between the information tracks Ta. The tracking track Tb is used as a guide for auto tracking (hereinafter, referred to as AT) for controlling the light beam spot so as not to deviate from a predetermined information track when scanning the light beam spot during information recording and reproduction. .

FIG. 3 shows one row of a block diagram of a tracking control unit used in a conventional optical information recording / reproducing apparatus.

The light beam reflected from the medium enters the AT photodetectors 33a and 33c, the signals from the respective detectors are input to the AT difference signal amplifier 1, and the output tracking error signal Sc is output to the phase compensator 8. The phase is appropriately compensated, and the signal is input to the AT coil driver 9 through the switch SW24, and the output signal is output to the AT coil 10
Drive. The objective lens 14 is integrated with the AT coil 10, and the objective lens 14 moves in a direction orthogonal to the track by the electromagnetic force between the AT coil 10 and the magnet 17. When the objective lens moves, the amount of light incident on the AT photodetectors 33a and 33c changes, so that the signal from each detector changes and the tracking error signal Sc changes. In this way, in the case of the auto tracking control, the AT servo circuit is closed to prevent the light beam spot from deviating from a predetermined information track when scanning the light beam spot during information recording and reproduction.

Next, when performing a track jump which is an operation of shifting the tracking from the state where the light beam spot is tracked to one information track to an adjacent track or a track several tracks ahead, first, the switching circuit 24 is switched from the command circuit 20 to the switching circuit 24. Is sent to open the tracking servo circuit. At the same time, the command circuit 20 outputs a track jump command signal to the track jump pulse generation circuit 21. The track jump pulse is sent from the track jump pulse generation circuit 21 to the addition amplifier 23. AT
A low frequency component is extracted from the tracking error signal Sc output from the difference signal amplifier 1 by the low-pass filter 22 and is input to the other input terminal of the addition amplifier 23. This input signal is used to correct that the skew amount, which is the difference between the moving direction of the medium during the scanning of the medium and the direction of the information track, affects the track jump. A drive pulse in which the skew amount for the track jump is corrected is generated by the addition amplifier 23, and the objective lens moves by a distance determined by the drive pulse via the switching SW 24 and the AT coil driver 9.

When the track jump is completed, the switching signal Sa is sent from the command circuit 20 to the switching SW 24, the switching SW 24 is switched, and the tracking servo circuit is closed. Since the light beam spot has just moved to the vicinity of the target track by the previous track jump operation, tracking pull-in is performed there, and the auto tracking state is maintained thereafter.

[Problems to be solved by the invention]

However, in the above conventional example, the moving distance by the track jump changes depending on the pulse width and pulse voltage of the pulse output from the track jump pulse generating circuit 21 and the frequency characteristics of the actuator, and furthermore, the actual position of the objective lens is not detected. Therefore, there is a drawback that it is difficult to accurately perform a track jump over a certain distance. As a result, the tracking pull-in is performed on a track different from the target information track, or a correction time required for correcting the pull-in to the correct information track is required.

An object of the present invention is to provide an optical information recording / reproducing apparatus capable of performing an accurate and quick tracking jump to a target track in view of such a problem.

[Means for Solving the Problems] It is an object of the present invention to provide an optical information recording / reproducing apparatus which performs a track jump for jumping a light spot to a target track by moving an objective lens in the optical head. A tracking actuator mounted on the optical head for moving the objective lens within the optical head; a means for generating a current position signal indicating a relative position of the objective lens in the direction of the movement with respect to the optical head main body; Means for generating a target position signal indicating a position of a target track to be moved; and a position servo circuit for controlling the tracking actuator based on the current position signal and the target position signal, wherein the position servo circuit controls the objective lens. Performing the track jump while performing the position servo control. This is achieved by an optical information recording / reproducing apparatus.

〔Example〕

First, an overall configuration of an optical card recording / reproducing apparatus as one embodiment of the present invention will be described with reference to FIG.

In the figure, a recording / reproducing apparatus 30 introduces an optical card C into the recording / reproducing apparatus 30 via a transport mechanism (not shown) by the rotation of a drive motor 31 and reciprocates in the R direction.
Discharge to outside 30. The optical card C is irradiated with a light beam spot from a light beam irradiation optical system 32 including a light source during information recording and information reproduction. In the present embodiment, three light beam spots are formed on the optical card C during recording and reproduction,
The reflected lights of the three light beam spots are received by the photodetectors 33a to 33c, respectively. The auto-focusing actuator 34 drives a part of the light beam irradiation optical system 32 to move the focus position of the light beam spot on the optical card surface in the Z direction, that is, the direction perpendicular to the optical card surface, to thereby perform auto-focusing (hereinafter, referred to as “auto-focusing”). AF). The AT actuator 35 drives a part of the light beam irradiation optical system 32 to move the light beam spot on the optical card surface in the Y direction (that is, in a direction orthogonal to both the R direction and the Z direction) to perform AT. Is performed.

Optical head including light beam irradiation optical system 32, photodetectors 33a to 33c, AF actuator 34 and AT actuator 35
36 are configured. The drive motor 37 moves the light beam spot beyond the movable range of the objective lens provided in the optical head 36, for example, when moving the light beam spot in the Y direction to access a desired track on the optical card. In this case, this is for moving the entire optical head 36 in the Y direction. The drive motors 31 and 37 are controlled by the control circuit 38.

Outputs of the photodetectors 33a to 33c are input to an AT / AF control circuit 39. The control circuit 39 controls the AF actuator 34 and the AT actuator 35 to perform auto-focusing (AF) and auto-tracking (AT).

The outputs of the photodetectors 33a to 33c are also input to the modulation / demodulation circuit 40, where the read information is demodulated. The demodulated signal is sent to the control circuit 38. Also, this modulation / demodulation circuit 40
Modulates the information signal sent from the control circuit 38, and drives the light beam irradiation optical system 32 according to the modulated signal to record information.

The control circuit 38 is controlled by a main controller 41 having a CPU configuration, and exchanges data with the main controller 41.

FIG. 5 is a perspective view showing details of the optical head part of FIG.

In the figure, a light beam emitted from a semiconductor laser 50 becomes a divergent light beam, enters a collimator lens 51, and is converted into a parallel light beam by this lens. The parallel light beam is shaped into a predetermined light intensity distribution by a light beam shaping prism 52, and then enters a diffraction grating 53, where the three effective diffraction light beams (0th-order diffraction light and ± 1st-order diffraction light) are formed.
Is divided into These three light beams are incident on the beam splitter 54, travel straight through, are reflected by the reflection prism 55 and are incident on the objective lens 56, are focused by passing through them, and are focused on the optical card C by three minute beams. Light beam spots S1 (corresponding to + 1st order diffracted light), S2 (0
S3 (corresponds to -1st-order diffracted light)
To form

The light beam spots S1 and S3 are located on adjacent tracking tracks, and the light beam spot S2 is located on an information track between the tracking tracks. Thus, the reflected light from the light beam spot formed on the optical card C is made substantially parallel through the objective lens 56, reflected by the reflecting prism 55, further reflected by the beam splitter 54, and focused by the focusing lens system 57. Being
The light enters the photodetectors 33a, 33b, and 33c. These light detectors 33a
The detection signals from .about.33c correspond to the AT / AF control circuit 39 in FIG.
The control circuit 39 controls the AT actuator 35 and the AF actuator 34 based on the input.

FIG. 1 is a schematic diagram of an AT control circuit unit 39 according to the present embodiment.

The signals of the AT photodetectors 33a and 33c are input to the AT difference signal amplifier 1, and a tracking error signal Sc is generated. This signal drives the AT coil 10 via the switching SW 2, the objective lens position controller 6, which is a difference signal amplifier, the position compensation circuit 8, and the AT coil driver 9, controls the objective lens 14, and performs tracking.

On the other hand, the light beam emitted from the light emitting diode 12 is reflected by the reflecting surface 11 attached to the actuator support 15 integrated with the objective lens 14, and the phototransistor
13 and is input to the A / D converter 4 as a current position signal Sa indicating the current position of the objective lens in the tracking direction,
The data is converted into a digital value at an appropriate sampling interval and input to the control unit 5. The position signal Sa of the objective lens 14 in the tracking direction is connected to the switch terminal b of the switching SW2. The A / D converter 3 converts the tracking error signal Sc into a digital value at an appropriate sampling interval, and inputs the digital value to the control unit 5.

Also, the control unit 5 controls the objective lens 14 when the track jumps.
Is input to the D / A converter 7 and the D / A
It is converted and input to the objective lens position controller 6 as a position control signal Sb.

Next, the operation at the time of a track jump of the present embodiment having the above configuration will be described. FIG. 2 is a signal diagram for explaining the operation at the time of a track jump. FIG.
(B) and (c) are signals Sa and S on the same time axis, respectively.
The state of change of b and Sc is shown. FIG. 2 shows a case where a two-track jump is performed.

Now, it is assumed that the switching SW2 is connected to the a side by a command from the control unit 5 and is tracked to a certain track on the recording / reproducing medium. That is, the AT photodetector 33a and the AT photodetector 33c
The tracking signal detected in step (1) is input to the AT difference signal amplifier 1, output as a tracking error signal Sc, input to one input of the objective lens position controller 6 via the switch SW2, and output to the phase compensation circuit 8 and the AT coil driver. AT coil after 9
By driving the objective lens 14, the objective lens 14 is controlled, and the AT servo circuit that the movement of the objective lens appears as a change in the output of the AT photodetectors 33a and 33c is closed. Note that the offset voltage Sb input from the D / A converter 7 to the other input terminal of the objective lens position controller 6 is set to zero. During this state time 0 to t _1, as shown in the objective lens position signal Sa is a second view showing the relative positions of the actuator body 16 which is integrated with the objective lens 14 and the optical head (a) S It is assumed that the point has changed from point A to point A.

Next, a track jump is performed at point A. In this embodiment, first, the objective lens 14 is moved to a first target position B near the final target (second target) position C of the track jump. A method of sweeping the objective lens 14 to the target C is executed.

Therefore, first, the voltage a of the objective lens position signal Sa at the time t ₁ (point A) input from the A / D converter 4 to the control unit 5 and detected, and the moving distance of the objective lens 14 to the first target due to the track jump Is transmitted from the control unit 5 to the D / A converter 7 so that the voltage of a + b, which is obtained by adding the change voltage b of the objective lens position signal Sa, is output from the D / A converter 7. Therefore, the voltage of a + b is input to the objective lens position controller 6 (FIG. 2 (b)). At the same time, switch SW by command from control unit 5
2 is switched to the b side, and the servo loop is switched from tracking servo to position servo of the objective lens. Voltage Sb is input to one immediately a + b becomes the objective lens position controller 6 at time t _1, the other objective lens position controller 6 for the objective lens position signal Sa is input, the difference signal is Zohaba The objective lens 14 moves so as to reduce the difference, and finally reaches the first target point B accurately. Incidentally, the objective lens 14 for the transient response of the actuator represents the movement as shown in point A ~B point of FIG. 2 (a), in the final settling to time t ₂ located in point B I have.

Next, the value C of the objective lens position signal Sa when the objective lens 14 is at the final target point is set as the signal voltage Sb so that the objective lens 14 reaches the second target (final target) C point. The signal voltage Sb linearly increases (or decreases) by gradually changing and outputting the value from the control unit 5 to the D / A converter 7. The objective lens position servo loop is formed based on the signal voltage Sb, but since the signal voltage Sb changes gradually and linearly, the objective lens position signal Sa also changes gradually similarly to the signal voltage Sb. Draw a trajectory.

During this time, the control unit 5 monitors the tracking error signal Sc, which is the output of the AT difference signal amplifier 1, via the A / D converter 3. When the objective lens 14 reaches the final target point C, the tracking error signal Sc is output. Since the Sc curve crosses the horizontal axis of voltage 0,
At this time, a command is sent from the control unit 5 to the switching SW2 to switch to the a side. At the same time, the D / A converter 7 from the control unit 5 sets the offset voltage Sb to a predetermined value (here, temporarily 0).
Output value to As a result, the servo loop is switched from the position servo of the objective lens to the original tracking servo, and the track jump to the target track is completed.

Since the signal voltage Sb is gradually changed (swept) when the objective lens 14 reaches the final target point C,
The tracking error signal Sc also draws a smooth curve, so that it is possible to reliably detect the time when the curve of the tracking error signal Sc crosses the horizontal axis of the voltage 0, and to accurately shift to the tracking servo. The final goal C
Up to the point B near the point, the offset voltage a + b is instantaneously applied to reach the point B, so that the time required for the track jump can be further shortened.

In this embodiment, the movement of the objective lens 14 to the first target is executed by instantaneously applying the offset voltage Sb, but the sweep movement is more rapid than the movement of the objective lens from the first target to the second target. May be executed.

Further, the objective lens may be swept directly from the start point of the track jump to the target track. At this time, if the track jumps to an adjacent track, the AT error signal Sc can be monitored and tracking can be performed on the first track. If the track jumps between multiple tracks, the number of tracks traversed by the AT error signal Sc can be monitored. Then, it is only necessary to perform tracking pull-in at the point where the target track is reached.

Further, in the above embodiment, the light emitting diode and the phototransistor are used as the objective lens position detecting means. However, any other means that can detect the position, such as those using a Hall element, a linear pulse encoder,
A device utilizing reflection of ultrasonic waves may be used.

Further, the present embodiment relates to an optical card recording / reproducing apparatus. However, the present invention relates to an optical card recording / reproducing apparatus using an optical sheet, an optical disc having a rotating track, and the like. The present invention can be applied to an optical information recording / reproducing apparatus capable of recording information on an optical information recording medium and / or reproducing information recorded on the optical information recording medium by relatively moving a light spot while tracking the same.

〔The invention's effect〕

As described above, according to the present invention, the light spot can be accurately and quickly moved by a necessary distance by directly moving the objective lens using the position servo control and performing the track jump. That is, an accurate and quick track jump can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of an AT control circuit unit according to an embodiment of the present invention,
FIG. 2 is a signal diagram for explaining an operation at the time of a track jump according to the embodiment of the present invention, FIG. 3 is a schematic diagram of an AT control circuit section according to a conventional example, and FIG. FIG. 5 is a perspective view showing details of an optical head part in FIG. 4, FIG. 6 is a schematic plan view of a write-once optical card, and FIG. 7 is FIG. 3 is an enlarged view of a track portion of FIG. 32: Light beam irradiation optical system, 33a, 33c: AT photodetector, 35: A
T actuator, 36 ... Optical head, 56 ... Objective lens, C
… Optical card, S1 to S3… light beam spot, Ta… information track, Tb… tracking track.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-157331 (JP, A) JP-A-62-180533 (JP, A) JP-A-63-37828 (JP, A) 260427 (JP, A) JP-A-60-66340 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 7/085

Claims (2)

(57) [Claims] 1. An optical information recording / reproducing apparatus for performing a track jump for jumping a light spot to a target track by moving an objective lens in an optical head, wherein the objective lens is moved in the optical head. A tracking actuator mounted on the optical head; a means for generating a current position signal indicating a relative position of the objective lens in the direction of the movement with respect to the optical head body; a target indicating a position of a target track of the light spot to be moved Means for generating a position signal; and a position servo circuit for controlling the tracking actuator based on the current position signal and the target position signal, wherein the track jump is performed while performing position servo control of the objective lens by the position servo circuit. Optical information recording / reproducing apparatus characterized by performing . 2. The optical information recording / reproducing apparatus according to claim 1, wherein said target position signal generating means changes said target position signal according to a distance to said target track.