JPH0787026B2 - Target signal search device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to coarse feeding for moving an optical pickup device itself in a tracking direction of a signal recording medium and moving movable optical parts of the optical pickup device in the tracking direction. The present invention relates to a target signal search device that searches for a target signal track by minute feed.

(B) Conventional Technology An optical reproducing device for optically reproducing a signal recorded on a signal recording medium by using an optical pickup device, for example, a CD player or a laser vision player is known. As is well known, the optical reproducing apparatus records a sub data signal of position index information indicating the position of the disc in addition to a main data signal such as music information and video information. Specifically, for CDs, index information called TOC in the lead-in area (for music CDs, the start position of each song, total number of songs, total playing time, etc.)
Is recorded and a sub-data signal called a sub-coding signal, which completes one block in a cycle of 1/75 second by reproduction, is recorded, and the sub-coding signal is composed of 8 channels of P to W channels. In a music CD, the position index information indicating the beginning of the song on the P channel, the position index indicating the absolute elapsed time from the start point of the signal track on the Q channel, the elapsed time of each song, the song number, and the index Information is recorded. Therefore, the optical reproducing device is usually equipped with a target signal searching device so as to search for a data signal such as the beginning of a target piece of music designated by manual operation by using the position index information. In the case of a CD-ROM, since the position index information is also included in the main data signal, the position index information can also be used in the search in the CD-ROM drive device to make the search more accurate. .

The target signal search device of such an optical reproducing device is usually a target signal to be searched for and created based on position data corresponding to the current position of the optical pickup device and position index information recorded on a signal recording medium. The difference from the target data corresponding to the position of the track is compared, and the feed amount and the direction of the optical pickup device are determined according to the difference to perform the search. Here, as the target signal search device, a movable optical component for tracking such as coarse feed for moving the optical pickup device itself in the tracking direction of the signal recording medium and tracking of an objective lens of the optical pickup device is moved in the tracking direction. In general, the target signal track is searched by the minute feed.
That is, if the target signal track position is separated from the reproduction position by the optical pickup device by a predetermined distance or more, the target signal search device moves the reproduction position closer to the target signal track by coarse feed and then performs fine feed. The reproduction position is accurately matched with the target signal track.
Therefore, such a target signal search device is advantageous in shortening the search time.

By the way, the target signal search device needs to recognize the current position of the optical pickup device by capturing the signal track with the light beam from the optical pickup device and pulling it into the tracking servo state immediately before switching to the search operation by minute feed. . Here, when the optical pickup device is displaced in the tracking direction by rough feed, the movable optical component for tracking is vibrated due to the acceleration or inertia when the optical pickup device is stopped. Takes time to capture
It is not possible to switch from coarse feed to minute feed immediately. In particular, since the number of optical pickup devices that use a linear motor to displace the optical pickup device at a high speed in order to shorten the search time is increasing, the vibration of the movable optical component becomes more problematic. In order to solve this problem, attention is paid to the fact that the driving current supplied to the linear motor for driving the optical pickup device is substantially proportional to the acceleration of the optical pickup device, as disclosed in, for example, Japanese Patent Laid-Open No. 59-165278. Then, a signal proportional to the drive current supplied to the linear motor is supplied to a drive optical component (objective lens) for tracking, and vibration of the movable optical component is prevented to shorten the time for capturing a signal track. , Those that shorten the search time have been proposed.

(C) Problems to be Solved by the Invention However, in practice, the drive current of the linear motor is inevitably caused by factors such as friction of the drive mechanism of the optical pickup device or external force such as inclination of the drive mechanism. Not proportional to the acceleration of the optical pickup device. Therefore, in the end, the vibration of the movable optical component for tracking control could not be sufficiently suppressed.

Moreover, in the actual search operation, due to the inertia of the optical pickup device, the play of the drive mechanism, the electric time constant of the feed servo system, and the resolution of the position detection system of the optical pickup device, it is detected that the rough feed operation has ended. At that point, the movement of the optical pickup device could not be stopped immediately.
Therefore, the acquisition operation of the signal track after the rough feed is not successful, which hinders the shortening of the search time, and in the worst case, it is not drawn into the tracking servo state within the preset time, and the search operation Was sometimes discontinued.

(D) Means for Solving the Problems The present invention has been made in view of the above points, and includes a linear motor for performing rough feed, a linear motor drive circuit for supplying a drive current to the linear motor, A first signal generating circuit for generating a linear motor signal according to a drive current supplied from the linear motor drive circuit, a moving distance detecting means for detecting a moving distance of the optical pickup device, and a moving distance detecting means. A second signal generating circuit for converting the distance signal to be converted into an acceleration signal corresponding to the moving acceleration of the optical pickup device, a linear motor signal from the first signal generating circuit, and an acceleration from the second signal generating circuit. And a switch circuit for selectively supplying a signal to the tracking coil drive circuit, and accelerating the tracking coil drive circuit for a predetermined period until the end of rough feed. And in the manner switching the switching circuit so as to supply the linear motor signal instead of the signal.

Further, according to the present invention, a tracking error detection circuit for detecting a tracking error of a light beam generated from an optical pickup device to a signal track, and a tracking error signal from the tracking error detection circuit causes the light beam to cross the signal track. Track cross signal detecting means for detecting a track cross signal that is sometimes generated and detecting that the track cross signal is equal to or lower than a predetermined frequency capable of capturing a signal track set according to the tracking servo characteristic. The linear motor signal is supplied to the tracking coil drive circuit until the signal detecting means detects a track cross signal having a frequency equal to or lower than a predetermined frequency.

(E) Operation In the present invention, when the movement of the optical pickup device during the search by rough feed is stable, the acceleration signal generated from the second signal generating circuit approximates the actual acceleration of the optical pickup device, During the predetermined period until the end of the movement of the optical pickup device at the time of searching by rough feed, there is a structural problem such as backlash of the drive mechanism that drives the optical pickup device, or the movement distance of the optical pickup device in a low speed range. First due to the resolution problem of the detection means
Paying attention to the fact that the linear motor signal generated from the signal generation circuit of 1 is similar to the actual acceleration of the optical pickup device, the linear acceleration signal is changed to the tracking coil drive circuit for a predetermined period until the end of rough feed. The motor signal is supplied.

Further, the present invention supplies the linear motor signal to the tracking coil drive circuit until a track cross signal having a predetermined frequency or less capable of capturing a signal track set in consideration of the tracking servo characteristic appears, and the track cross signal is When the signal appears, the signal track is captured, and the signal is surely pulled into the tracking servo state, and immediately shifts to the minute feed.

(F) Embodiment FIG. 1 is a circuit diagram showing an embodiment of the present invention. (1) is a semiconductor laser (2) as a light source and a half for splitting an optical path and generating astigmatism. A mirror (3),
An objective lens (5) supported so as to be displaceable in the tracking direction and the focusing direction of the disc (4) and a photodetector (6) having a detection element for detecting tracking deviation of a light beam to a signal track are provided. An optical pickup device, which is supported so as to be displaceable in the tracking direction of the disc (4), (7) uses an output signal from the photodetector (6) to track a light beam of the optical pickup device (1) to a signal track. A tracking error detection circuit indicating an error, and (8) a phase for phase-compensating an output signal from the tracking error detection circuit (7) according to a drive system in the tracking direction of the objective lens (5) of the optical pickup device (1). Compensation circuit,
(9) is a tracking coil drive circuit that supplies a drive current to a tracking coil (10) for driving the objective lens (5) in the tracking direction, and (11) drives the optical pickup device (1) in the tracking direction. The linear motor for ( 12 ) is the optical pickup device (1)
A linear encoder (15) which is fixed to the main scale (13) and is displaced according to the movement of the optical pickup device (1), and a detection section (14) for detecting the movement of the main scale (13). Decodes the coded output signal from the linear encoder ( 12 ) and converts it into a pulse signal which is waveform-shaped and multiplied, and at the same time, the optical pickup device (1) according to the output signal supplied from the linear encoder ( 12 ). ) Positive output ends (16a) and (17
a) or a decoder that outputs pulse signals from the negative output terminals (16b) and (17b), (18) is the position index information recorded on the currently playing disc (4) from the input terminal (19) A position data creation circuit that is supplied and creates position data according to the current position of the optical pickup device (1) based on the position index information, and (20) is pulling information reproduced when the disc (4) is mounted. RAM stored
A target data setting circuit for setting traction information according to the search target specified by the input means (22) from (21),
(23) detects a difference between the position data created by the position data creating circuit (18) and the target data set by the target data setting circuit (20), and based on the difference, detects the optical pickup device (1 ) Target position calculation circuit for calculating the distance from the current position to the target position that is the position of the target signal track, (24) sets the count value according to the numerical value calculated by the target position calculation circuit (23) And is counted down according to the pulse signal output from the positive output end (16a) of the decoder (15), and according to the pulse signal output from the negative output end (16b) of the decoder (15). Deviation counter that is incremented, (2
Reference numeral 5) is a speed reference signal generating circuit for generating a speed reference signal serving as a reference for the speed at which the optical pickup device (1) is moved according to the count value of the deviation counter (24), and (26) is a frequency signal for a voltage signal. And a positive and negative output terminal (17) of the decoder (15).
a speed signal generation circuit for generating a speed signal whose voltage value changes according to the moving speed of the optical pickup device (1) based on the number of pulse signals output from (a) and (17b) per unit time; ) Is a differentiating circuit for differentiating the speed signal from the speed signal generating circuit (26) to convert it into an acceleration signal corresponding to the acceleration of the optical pickup device (1), and (28) is the speed reference signal generating circuit (25). A subtraction circuit for subtracting a speed reference signal output from the speed signal generation circuit (26) and a speed signal output from the speed signal generation circuit (26), and an output signal from the subtraction circuit (28) to an optical pickup device (1) A phase compensation circuit for compensating the phase in accordance with the drive system of the linear motor drive circuit, (30) supplying a drive current to the linear motor (11) in response to an output signal from the phase compensation circuit (29), (31) Is supplied to the linear motor (11) A resistor for generating a voltage according to the driving current to be generated, (32) is a linear motor for generating a linear motor signal according to the driving current supplied to the linear motor (11) from the potential difference across the resistor (31). Motor signal generating circuit, (33) is the linear motor signal generating circuit (3
A first switch circuit that selectively supplies the linear motor signal from 2) and the acceleration signal from the differentiating circuit (27) to the next stage, and (34) is the phase of the signal from the first switch circuit (33). A second switch circuit for selectively supplying the signal from the compensation circuit (8) to the tracking coil drive circuit (9),
(35) is a servo switch for turning on / off the tracking servo, (36) is the first and second switch circuits (3
A switch control circuit for controlling switching between 3) and (34) and the servo switch (35), and (37) a deviation counter (24) for numerical values calculated by the target position calculation circuit (23).
A jump pulse signal generating circuit for generating a jump pulse signal for causing the objective lens (5) to make a track jump in accordance with the numerical value, which is less than the count value "1" of the tracking error detecting circuit (38). A waveform shaping circuit for converting the tracking error signal generated from 7) into a pulse signal, and (39) generating a pulse signal having a pulse width of a predetermined value or more generated from the waveform shaping circuit (38). The pulse width detection circuit detects whether or not a predetermined number of reference clocks are present during the operation, and generates a detection output when a pulse signal having a pulse width of a predetermined value or more is detected.

By the way, the jump pulse signal generation circuit (37) determines the direction in which the objective lens (5) is track-jumped according to whether the numerical value calculated by the target position calculation circuit (23) is positive or negative, and The distance and the number of times to perform the track jump are determined according to the above, and a jump pulse signal corresponding to the determination is generated.

Further, the waveform shaping circuit (38) and the pulse width detection circuit (39)
Is a track cross signal detection means (40) for detecting that the track cross signal generated when the light beam from the optical pickup device (1) crosses the signal track of the disc (4) is below a predetermined frequency. . That is,
The waveform shaping circuit (38) outputs a pulse signal obtained by converting the tracking error signal from the tracking error detection circuit (7) at a predetermined threshold level.
From the tracking error detection circuit (7), tracking is performed at a level of "0" when the light beam is correctly illuminating the signal track and at a level of "0", and when the light beam shifts to the left or right, the tracking is at a positive or negative level. An error signal is generated. Therefore, the tracking error signal becomes "0" level each time the light beam crosses the signal track. Therefore, if the threshold level of the waveform shaping circuit (38) is set to "0" level, the tracking error signal The 0 "level becomes the track cross signal,
A pulse signal is generated from the waveform shaping circuit (38) every time the light beam crosses the signal track. The pulse width of the pulse signal changes according to the frequency at which the track cross signal is generated. In this case, the pulse width of the pulse signal is inversely proportional to the frequency at which the track cross signal is generated. Therefore, the pulse width detection circuit (39)
Therefore, the detection output is generated when the track cross signal is equal to or lower than the predetermined frequency.

Further, a position data creating circuit (18), a target data setting circuit (20), a RAM (21), a target position calculating circuit (23), a speed reference signal generating circuit (25), a switch control circuit (36) and a jump pulse signal. The generating circuit (37) is composed of a microcomputer. Then, the switch control circuit (36) has a first value and a second value according to the count value of the deviation counter (24) and the detection output from the pulse width detection circuit (39).
A switching signal for switching the switch circuits (33) and (34) is generated, and a switching signal for switching the servo switch (35) is generated according to the jump pulse signal generation circuit (37). More specifically, the switch control circuit (36) includes a first switch circuit (3) that has been switched to the b side until now when the count value of the deviation counter (24) becomes “0”.
A switching signal for switching 3) to the side a is generated, and this switching signal continues to be generated until the track width signal of a predetermined frequency or less is detected by the pulse width detection circuit (39), and the search operation is performed by the input means (22). The deviation counter (24) based on the numerical value calculated by the target position calculation circuit (23)
When the count value is set to the second switch circuit (34)
A switching signal for switching to the b side is generated, and this switching signal continues to be generated until a track cross signal of a predetermined frequency or less is detected by the pulse width detection circuit (39), and the jump pulse signal generation circuit (37) jumps. Each time a pulse signal is generated, a switching signal for closing the servo switch (35) is generated.

Furthermore, linear encoders ( 12 ) and decoders (15)
Is a moving distance detecting means for detecting the moving distance of the optical pickup device (1), and an optical type linear encoder ( 12 ) is used, as shown in FIG. ) Is formed with a plurality of slits (41) arranged at equal intervals, and the detection unit (14) has a light emitting element (42) and a light receiving element (43) arranged to face each other across the main scale (13). ) And (44) are provided. In front of the light receiving elements (43) and (44), the auxiliary scale (45) has the same pitch as the slit (41) of the main scale (13) and the slit positions are different from each other by 1/4 pitch. And (46) are provided. Therefore, when the optical pickup device (1) is moved and the main scale (13) is displaced, the amount of light detected by the light receiving elements (43) and (44) changes, and at the same time, the light receiving elements (43) and (44). Output signals with different 90 ° phases can be obtained from 44).

In the apparatus configured as described above, when searching for a predetermined data signal, the inputting means (22) performs a search operation according to the target data signal. Then, the target data setting circuit (20) stores the search information corresponding to the search target from the index information of the disk (4) stored in the RAM (21) in advance according to the operation of the input means (22). Target data is set. On the other hand, the position data creation circuit (18) creates position data according to the current position of the optical pickup device (1) based on the position index information currently being reproduced supplied from the input terminal (19). Therefore, the target position calculation circuit (23) calculates the distance from the current position of the optical pickup device (1) to the target position, and the count value of the deviation counter (24) is set according to the calculated numerical value. Therefore, the speed reference signal generation circuit (25) generates a speed reference signal according to the count value. Since the speed reference signal generated from the speed reference signal generation circuit (25) is supplied to the linear motor drive circuit (30) via the subtraction circuit (28) and the phase compensation circuit (29), the linear motor drive circuit is driven. A drive current corresponding to the speed reference signal is generated from the circuit (30). Therefore, the linear motor (11) is driven according to the speed reference signal, the optical pickup device (1) is moved accordingly, and rough feed is performed. The count value set in the deviation counter (24) is set to a positive or negative numerical value depending on the direction of the target position with respect to the current position, and the speed reference signal generating circuit (depending on whether the count value is positive or negative). 25) generates speed reference signals having different polarities.

When the optical pickup device (1) moves, the main scale of the linear encoder (12) (13) moves, the output signal is generated from the detection unit of the linear encoder (12) (14) in accordance with the movement. The output signal generated from the detection section (14) is decoded by the decoder (15). Here, output signals generated from the two light receiving elements (43) and (44) are output from the detection section (14), and outputs generated from the light receiving elements (43) and (44), respectively. Since the signals differ in phase by 90 °, the moving direction of the optical pickup device (1) is determined by detecting the output signal whose phase is advanced by the decoder (15), and the reproduction position by the optical pickup device (1) is determined. If you are moving in the forward direction,
When pulse signals are generated from the positive output terminals (16a) and (17a) and the reproduction position by the optical pickup device (1) is moving in the returning direction, negative output terminals (16b) and (1)
A pulse signal is generated from 7b). The positive and negative output terminals (16a) and (16b) connected to the counter (24) generate one pulse per pitch of the main scale (13). ) Is connected to the positive and negative output terminals (17a) and (17b) to combine the output signals generated from the two light receiving elements (43) and (44) to form one pitch of the main scale (13). The resolution is increased so that 4 pulses are generated per hit.

Depending on the moving direction of the optical pickup device (1), the positive or negative output terminal (16a) or (16b) of the decoder (15)
When a pulse signal is generated from, the count value of the deviation counter (24) is counted down or counted up by one count, and approaches "0". The speed reference signal generated from the speed reference signal generation circuit (25) changes in accordance with the count value, and the optical pickup device (1) approaches as the count value approaches "0" from a predetermined value.
Changes so that the movement speed of becomes slower. Then, when the optical pickup device (1) eventually reaches the target position, the count value becomes "0", and the generation of the speed reference signal from the speed reference signal generation circuit (25) is stopped. Therefore, the movement of the optical pickup device (1) is stopped. At this time, since the reproduction position of the optical pickup device (1) is displaced within a range in which the reproduction position can be moved to the target signal track by the track jump by the objective lens (5), the objective lens (5) is driven thereafter. The target signal track is searched by the minute feed performed by the above.

On the other hand, depending on the movement of the optical pickup device (1), the positive or negative output terminal (17a) or (17) of the decoder (15)
When a pulse signal is output from b), the speed signal generation circuit (2
A speed signal corresponding to the moving speed of the optical pickup device (1) is generated from 6). Since this speed signal is input to the inverting input terminal of the subtraction circuit (28) in phase with the speed reference signal generated from the speed reference signal generation circuit (25), the moving speed of the optical pickup device (1) is negative. It functions as a feedback signal and is used to control the optical pickup device (1) so as to move accurately at a speed according to the speed reference signal.

By the way, when the optical pickup device (1) is roughly fed at high speed, no detection output is generated from the pulse width detection circuit (39), so the first switch circuit (33) is switched to the b side. At this time, the count value of the deviation counter (24) is naturally not "0", so the second switch circuit (34) is switched to the b side. For that reason,
The tracking coil drive circuit (9) includes a differentiation circuit (2
The acceleration signal generated from 7) is supplied.

On the other hand, the tracking error signal generated from the tracking error detection circuit (7) is always converted into a pulse signal by the waveform shaping circuit (38), and the pulse signal has a predetermined value or more by the pulse width detection circuit (39). Whether or not the pulse width is detected is detected. Then, when the pulse width detection circuit (39) detects a pulse signal having a pulse width of a predetermined value or more, the pulse width detection circuit (39) generates a detection output to the switch control circuit (36). When the count value of the deviation counter (24) becomes "0", the switch control circuit (36) generates a switching signal for switching the first switch circuit (33) to the a side. Therefore, the tracking coil drive circuit (9) is supplied with the linear motor signal generated from the linear motor signal generation circuit (32) after the count value of the deviation counter (24) becomes “0”. Become.
Therefore, the objective lens (5) is driven by the acceleration from the differentiating circuit (27) until the end of the rough feed in which the optical pickup device (1) moves at a speed faster than a predetermined speed during the search operation by the rough feed, The optical pickup device (1) is driven by a linear motor signal from the linear motor signal generation circuit (32) within a predetermined period until the end of the rough feed in which the optical pickup device (1) moves at a speed equal to or lower than a predetermined speed. Here, FIG. 3A shows the movement period during which the optical pickup device (1) is moved until the count value of the deviation counter (24) becomes “0”. the actual moving speed of the) is as shown in FIG. 3 (b), does not immediately "0" is also the count value of said deviation counter (24) at time t ₀ is set to "0". This is due to the inertia of the optical pickup device (1), the play of the drive mechanism, the electric time constant of the feed servo system, and the like. The actual acceleration of the optical pickup device (1) is as shown in FIG. On the other hand, the speed signal generation circuit (2
Since the velocity signal as shown in FIG. 3 (d) is generated from 6), the acceleration signal as shown in FIG. 3 (e) is generated from the differentiating circuit (27). Here, the speed signal generated from the speed signal generation circuit (26) has a structure such as backlash due to the difference between the fulcrum of the drive mechanism (not shown) of the optical pickup device (1) and the position of action. Due to the above, or due to the poor resolution in the low speed range due to the influence of the pitch interval of the slits (41) of the main scale (13) (detection omission of minute displacement due to resolution), the error from the actual speed is remarkable at the end of rough feed Becomes Therefore, the acceleration signal generated from the differentiating circuit (27) immediately before the end of the rough feed has a large error from the actual acceleration.

On the other hand, the linear motor signal generation circuit (32) has a resistor (31)
A linear motor signal corresponding to the drive current supplied to the linear motor (11) is output from the potential difference between both ends of the linear motor signal. The linear motor signal is as shown in FIG. That is, comparing the acceleration signal from the differentiating circuit (27) and the linear motor signal from the linear motor signal generating circuit (32) with the actual acceleration, when the optical pickup device (1) is moving at a high speed to some extent. In, the acceleration signal is
The linear motor signal approximates the actual acceleration immediately before the end of the rough feed in which the optical pickup device (1) moves at a low speed.

By the way, in the apparatus shown in FIG.
The switch circuit (33) switches from the b side to the a side when the count value of the deviation counter (24) becomes "0", and the state is changed by the pulse width detection circuit (39) to a pulse width of a predetermined value or more. Hold until pulse signal is detected. Therefore, the movement of the optical pickup device (1) and the disc (4)
From the waveform shaping circuit (38) to the third
When the track cross signal as shown in the figure (g) is generated,
At time t ₁ , the pulse width detection circuit (39) detects a pulse signal having a pulse width equal to or larger than a predetermined value, for example, TW, so that the period during which the first switch circuit (33) is switched to the side a is the third. It is shown as in FIG. That is, the optical pickup device is caused by the inertia of the optical pickup device (1), the play of the drive mechanism, the electric time constant of the feed servo system, and the like while the speed reference signal generating circuit (25) is not generating the speed signal. In the state where (1) is moving, the objective lens (5) is supplied with a signal corresponding to the linear motor signal from the linear motor signal generating circuit (32) instead of the acceleration signal from the differentiating circuit (27). It In addition, FIGS. 3 (g) and 3 (h) are partially enlarged on the horizontal axis.

Therefore, the objective lens (5) is driven according to a signal substantially equal to the actual acceleration of the optical pickup device (1) as shown in FIG.

On the other hand, when the pulse width detection circuit (39) detects a pulse signal having a pulse width equal to or larger than the predetermined value (TW), the second switch circuit (34) is switched from the b side to the a side and the servo switch (35). Is released, the tracking error signal is supplied to the tracking coil drive circuit (9) from the tracking error detection circuit (7) via the phase compensation circuit (8). Therefore, the objective lens (5) is brought into a tracking servo state in which it is driven according to the tracking error signal, and the position index information recorded on the disc (4) can be reproduced. In addition, FIG. 3 (nu) shows the timing to enter the tracking servo state.

Therefore, new position index information is input to the input terminal (19), new position data is created by the position data creation circuit (18), and the current playback position and the target are newly created by the target position calculation circuit (23). A numerical value is calculated according to the difference with the signal track. From the jump pulse signal generation circuit (37), the jump pulse is generated according to the amount which is less than the count value "1" of the deviation counter (24) calculated by the target position calculation circuit (23). The signal is generated and the switch control circuit (36) closes the servo switch (35) every time a jump pulse signal is generated, and the jump pulse signal is supplied to the tracking coil drive circuit (9). Therefore, the objective lens (5) is searched for the target signal track by minute feed driven in the tracking direction according to the jump pulse signal. And during this minute feed, 1
Every time a track jump is performed, the tracking servo state is set and a new current reproduction position is recognized, so that the search for the target signal track can be accurately achieved.

3 (A) to 3 (N), the horizontal axis represents time t, and the vertical axis represents voltage excluding FIGS. 3 (A), 3 (H) and 3 (N).

(G) Effect of the Invention As described above, the target signal search device according to the present invention supplies the linear motor signal by changing the acceleration signal to the tracking coil drive circuit for a predetermined period immediately before the end of the search operation by rough feed. As a result, vibrations of the movable optical components for tracking the optical pickup device can be suppressed, signal tracks can be easily captured, and fine feed can be smoothly performed.
Further, if the signal track is captured when the track cross signal having a frequency equal to or lower than the predetermined frequency set according to the tracking servo characteristic is detected, the signal track can be reliably captured and the target signal track can be obtained. This has the advantage of being advantageous in reducing the search time for searching.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the present invention, and FIG.
The figure is a model diagram showing a linear encoder, and Fig. 3 (a),
(B), (c), (d), (e), (f), (g),
(H), (ri) and (nu) are waveform charts provided for explaining the present invention. Description of main drawing numbers (1) …… Optical pickup device, (5) …… Objective lens, (9) …… Tracking coil drive circuit, (11)…
… Linear motor, ( 12 ) …… Linear encoder, (15)
…… Decoder, (18) …… Position data creation circuit, (20)
Target data setting circuit (23) Target position calculation circuit (24) Deviation counter (25) Speed reference signal generation circuit (26) Speed signal generation circuit (27) … Differentiation circuit, (28) …… Subtraction circuit, (30) …… Linear motor drive circuit, (32) …… Linear motor signal generation circuit, (3
3) …… first switch circuit, (34) …… second switch circuit, (35) …… servo switch, (36) …… switch control circuit, (38) …… waveform shaping circuit, (39) …… Pulse width detection circuit.

Claims (2)

[Claims] 1. An optical pickup device comprising a movable optical component displaceably supported so as to optically reproduce a signal recorded on a signal recording medium and to follow a signal track of the signal recording medium. A target signal retrieving device for retrieving a target signal track by a coarse feed for moving the pickup device itself in the tracking direction of a signal recording medium and a fine feed for moving the movable optical component in the tracking direction. A tracking coil drive circuit for supplying a drive current to drive the movable optical component in the tracking direction, a linear motor for performing rough feed, a linear motor drive circuit for supplying a drive current to the linear motor, and the linear motor A first signal generator that generates a linear motor signal according to the drive current supplied from the drive circuit A circuit, a moving distance detecting means for detecting a moving distance of the optical pickup device, and a second signal generating circuit for converting a distance signal obtained by the moving distance detecting means into an acceleration signal according to the moving acceleration of the optical pickup device. And a switch circuit for selectively supplying the linear motor signal from the first signal generation circuit and the acceleration signal from the second signal generation circuit to the tracking coil drive circuit, and a search operation by rough feed A target signal retrieving apparatus, wherein the switch circuit is switched so as to supply a linear motor signal instead of an acceleration signal to the tracking coil drive circuit for a predetermined period just before the end of time. 2. A tracking error detection circuit for detecting a tracking error of a light beam generated from an optical pickup device to a signal track, and a tracking error signal from the tracking error detection circuit, Track cross signal detecting means for detecting a track cross signal generated when a track is crossed, and for detecting that the track cross signal is below a predetermined frequency capable of capturing a signal track set according to the tracking servo characteristic. A target signal retrieving apparatus characterized in that a linear motor signal is supplied to a tracking coil drive circuit until a track cross signal having a frequency equal to or lower than a predetermined frequency is detected by the track cross signal detecting means.