JP5169847B2 - Optical disk drive and focus search control method - Google Patents

Description

  The present invention relates to a focus search control technique in an optical disk drive device, and more particularly to vibration countermeasures in an in-vehicle optical disk drive device.

  FIG. 7 is a configuration diagram of a conventional optical disk drive device described in Patent Document 1 below, and specifically shows a focus servo circuit thereof.

  This optical disk drive reads out data recorded on an optical disk such as a CD or a DVD. A spindle motor 10 that holds and rotates the optical disk 1 to be read, and a laser beam on the data recording surface of the optical disk 1. An optical pickup 20 for irradiating and detecting the reflected light is provided.

  The optical pickup 20 includes a laser diode (LD) 21 that outputs laser light and a photodetector (DET) 22 that receives the laser light reflected by the optical disc 1, as well as a half mirror 23 and a biaxial actuator 24. Yes. The half mirror 23 allows the laser beam output from the laser diode 21 to pass through and irradiates the optical disc 1, and reflects the laser beam reflected by the optical disc 1 to guide it to the photodetector 22.

  The biaxial actuator 24 moves the position of the objective lens 24a in the radial direction of the optical disc 1 (hereinafter referred to as the “X direction”) so that the laser beam that has passed through the half mirror 23 is focused on the recording track on the data recording surface of the optical disc 1. And control in the direction perpendicular to the data recording surface of the optical disc 1 (hereinafter referred to as “Y direction”).

  The detection signal output from the photodetector 22 is given to the arithmetic control circuit 30. The readout signal RF from the arithmetic control circuit 30, the focus information FOK indicating correct focus, and the degree of deviation from the focus are shown. A tracking error signal TE, a focus error signal FE, and the like are output.

  The tracking error signal TE is given to the tracking servo circuit 40, and the tracking servo circuit 40 controls the biaxial actuator 24 of the optical pickup 20 in the X direction so that the recording track of the optical disc 1 is traced by the laser beam. ing.

  On the other hand, the focus error signal FE is given to the focus servo circuit 50, and the biaxial actuator 24 of the optical pickup 20 is controlled in the Y-axis direction by the focus servo circuit 50 so that the laser beam is focused on the data recording surface of the optical disc 1. To be controlled. The focus servo circuit 50 includes a zero cross detector 51, a phase compensator 52, a switch 53, a focus driver 54, and a search signal generator 60.

The zero-cross detection unit 51 detects that the focus error signal FE has become zero (that is, is in focus) and outputs a zero-cross detection signal FZC. The zero cross detection signal FZC is given to the system control circuit 70.
The phase compensation unit 52 controls the biaxial actuator 24 so that the laser beam is always focused on the data recording surface of the optical disc 1 when data is read from the optical disc 1 (that is, in the servo operation mode). In addition, the phase compensation processing of the focus error signal FE is performed.

  The switch 53 switches a signal to be given to the focus driver 54 in accordance with the mode signal MOD given from the system control circuit 70. The switch 53 selects a search signal from the search signal generation unit 60 in the search operation mode such as when the optical disc 1 is activated, and in the servo operation mode such as when data is read after the optical disc 1 is activated, the phase compensation unit 52. The focus error signal FE having undergone phase compensation is selected and output. The focus driver 54 drives the biaxial actuator 24 of the optical pickup 20 in the Y direction in accordance with a signal given from the switch 53.

  The search signal generator 60 moves the biaxial actuator 24 up and down at a constant speed in the Y direction in order to focus the laser light emitted from the optical pickup 20 on the data recording surface of the optical disc 1 in the search operation mode. A search signal (that is, a triangular wave signal) is generated.

  The search signal generator 60 includes constant current sources 61 and 62 that flow constant currents having the same current magnitude and reverse direction, and switches 63 and 62 for turning on and off the currents of the constant current sources 61 and 62. 64. The switch 63 is turned on when the control signal UP is given from the system control circuit 70, and outputs the current of the constant current source 61 to the node N. On the other hand, the switch 64 is turned on when the control signal DN is given from the system control circuit 70 and connects between the constant current source 62 and the node N.

  The node N is connected to a time constant circuit 65 composed of a resistor and a capacitor, and to an operational amplifier 66 constituting a voltage follower. The output side of the operational amplifier 66 is connected to the switch 53.

  Although not shown, the optical disk drive includes a sled mechanism that is controlled from the system control circuit 70 via a servo circuit. The sled mechanism is for sliding the entire optical pickup 20 in the X direction of the optical disc 1 over the entire recording area.

Next, the focus search operation in the optical disk drive apparatus of FIG. 7 will be described.
When it is detected by a sensor (not shown) that the optical disk 1 is loaded on the spindle motor 10, the system control circuit 70 performs instruction control so as to drive the spindle motor 10 to rotate. Thereby, the optical disk 1 is rotationally driven in a certain direction.

  At the same time, the TOC area (usually the storage area of the optical disk 1) in which TOC (Table of Contents) information for managing the data area of the optical disk 1 is recorded from the system control circuit 70 to the thread mechanism. To move to the innermost peripheral side). As a result, the entire optical pickup 20 moves to just below the TOC area of the optical disc 1.

  Next, a mode signal MOD for designating a search operation is output from the system control circuit 70 to the focus servo circuit 50, and the output side of the search signal generator 60 is connected to the focus driver 54 via the switch 53.

  Furthermore, the system control circuit 70 outputs a control signal UP for search-up processing to the search signal generator 60 and sets a timer for monitoring the output time of the control signal UP. The switch 63 is turned on by the control signal UP, and a constant current flows from the constant current source 61 to the time constant circuit 65 connected to the node N, and the potential of the node N rises from 0 at a constant speed.

  The potential of the node N is supplied as a search signal to the focus driver 54 through the operational amplifier 66, and the biaxial actuator 24 of the optical pickup 20 is driven by the focus driver 54. As a result, the objective lens 24 a rises at a constant speed from the reference position corresponding to the potential 0 of the node N and approaches the data recording surface of the optical disc 1.

  As the objective lens 24a rises, the signal output from the photodetector 22 of the optical pickup 20 changes, and when the focus error signal FE output from the arithmetic control circuit 30 becomes 0, the zero cross detection unit of the focus servo circuit 50 51 outputs a zero-cross detection signal FZC.

  When the zero-cross detection signal FZC is given, the system control circuit 70 temporarily stops the operation of the timer and the search signal generation unit 60, switches the switch 53 with the mode signal MOD, and outputs the output signal of the phase compensation unit 52 to the focus driver 54. To switch to servo operation. Thereby, a focus servo loop of the optical pickup 20 → the arithmetic control circuit 30 → the phase compensation unit 52 → the focus driver 54 → the optical pickup 20 is formed.

  When the focus error signal FE is maintained below the threshold value for a certain time by the focus servo loop, it is determined that the servo pull-in is successful, and the arithmetic control circuit 30 indicates that focus information FOK is correctly focused. Is output. As a result, the system control circuit 70 proceeds to the next processing such as demodulation of the read signal RF and reading of data based on the demodulated TOC information.

  When the focus error signal FE is not maintained below the threshold value for a certain time by the focus servo loop, the focus information FOK is not output. In such a case, the system control circuit 70 determines that the servo pull-in has failed, returns to the search operation by the mode signal MOD, and restarts the operation of the timer and the search signal generator 60 that have been temporarily stopped, Perform search-up processing.

  When the timer detects a time-over, the system control circuit 70 uses the control signal DN instead of the control signal UP to the search signal generator 60 in order to end the search-up process and start the search-down process. In addition to outputting, a timer for monitoring the output time of the control signal DN is set. The switch 64 is turned on by the control signal DN, a constant current flows from the time constant circuit 65 through the node N to the constant current source 61, and the potential of the node N decreases at a constant speed. As a result, the objective lens 24a moves down at a constant speed and moves away from the data recording surface of the optical disc 1.

  When the zero cross detection signal FZC is detected during the search-down process, the system control circuit 70 temporarily stops the search operation and switches to the servo operation, and determines whether the servo pull-in is successful. If the servo pull-in is successful, the process proceeds to the next process. If the servo pull-in is unsuccessful, the remaining search-down process is resumed. When the timer detects time over, the search-down process is terminated and the search-up process is started again. These processes are repeated until the servo pull-in is successful.

  As described above, in this optical disk drive device, even when the servo pull-in fails after the zero-cross detection signal FZC is detected in the search-up process or the search-down process and switched to the servo operation, Returning to the state of the search down process, the search operation is continued. As a result, when the servo pull-in fails, the time until the servo pull-in succeeds can be remarkably reduced as compared with the method in which the search operation is performed from the initial state.

JP-A-7-78343

However, in the case of an on-vehicle optical disk drive device, since it is susceptible to disturbance due to vibration, there is a problem that servo pull-in may not succeed due to the influence of vibration even if search-up processing and search-down processing are repeated at a constant speed. there were.
An object of the present invention is to alleviate the influence of vibration and improve the probability of successful servo pull-in of an optical disk drive.

In order to achieve the above object, an optical disc driving apparatus according to the first aspect of the present invention applies light to a data recording surface of an optical disc through a lens, detects the reflected light, and converts it into an electrical signal. A pickup, a calculation means for generating a focus error signal indicating a focus state of the irradiation light based on the electrical signal, a position of the lens for controlling the focus of the irradiation light, and the irradiation light; An optical disc drive apparatus comprising: focus servo means for following the position of the lens based on the focus error signal when the focal point of the optical disc coincides with the data recording surface of the optical disc; and vibration detection means for detecting externally applied vibration The focus servo means moves the lens to a predetermined direction in order to adjust the focal position of the optical pickup. A search signal generator that can generate a plurality of search signals to be driven at different speeds, and a search signal for driving the lens at a predetermined speed in the search signal generator for the initial focus position search. When the focus position search fails when the lens is driven, a search signal for driving the lens is generated at a low speed sequentially when vibration exceeding a predetermined value is detected by the vibration detecting means. And a control unit that repeats the search of the focal position using the search signal of the predetermined speed when a vibration exceeding a certain value is not detected .

In the focus search control method according to the second aspect of the present invention, the data recording surface of the optical disc is irradiated with the irradiation light through the lens, the reflected light is detected and converted into an electrical signal, and the optical disc data is read out. In the optical disc driving apparatus, a focus search control method for controlling the position of the lens based on a plurality of search signals having different speeds in order to focus the irradiation light on the data recording surface, the first focus position search Then, when the lens is driven using a search signal at a predetermined speed and a focus position search fails, if a vibration exceeding a certain value is detected, a search signal with a low speed is sequentially generated to focus. If no vibration exceeding a certain value is detected, the focus position search is repeated using the search signal at the predetermined speed. It is, characterized in that.

  According to the present invention, when the focus position search fails in the focus search, the search speed is lowered and the focus search is repeated. As a result, the influence of vibration can be reduced and the probability of successful servo pull-in of the optical disk drive can be improved.

It is a block diagram which shows the optical disk drive device which concerns on embodiment of this invention. It is explanatory drawing of the focus search operation | movement of FIG. It is a flowchart of the focus search process in FIG. FIG. 4 is a flowchart of an initial search up process in FIG. 3. FIG. It is a flowchart of the search down process in FIG. It is a flowchart of the search up process in FIG. It is a block diagram which shows the conventional optical disk drive device.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing an optical disk drive apparatus according to an embodiment of the present invention. Elements common to those in FIG. 7 are given common reference numerals.
This optical disk drive reads out data recorded on an optical disk such as a CD or a DVD. Similar to the optical disk drive of FIG. 7, a spindle motor 10 that holds and rotates the optical disk 1 to be read, and this An optical pickup 20 for irradiating the data recording surface of the optical disc 1 with laser light and detecting the reflected light is provided.

  The optical pickup 20 includes a laser diode 21 that outputs laser light, a photodetector 22 that receives laser light reflected by the optical disc 1, a half mirror 23, and a biaxial actuator 24. The half mirror 23 allows the laser beam output from the laser diode 21 to pass through and irradiates the optical disc 1, and reflects the laser beam reflected by the optical disc 1 to guide it to the photodetector 22. The photodetector 22 detects reflected light of the optical disc 1 guided by the half mirror 23, performs photoelectric conversion, and outputs a detection signal.

  The biaxial actuator 24 moves the position of the objective lens 24a in the radial direction (X direction) of the optical disc 1 so that the laser beam that has passed through the half mirror 23 is focused on the recording track on the data recording surface of the optical disc 1. And fine adjustment in the direction perpendicular to the data recording surface of the optical disc 1 (Y direction).

  The detection signal output from the photodetector 22 is supplied to the arithmetic control circuit 30, and the readout signal RF, the focus information FOK, the tracking error signal TE, the focus error signal FE, and the like are output from the arithmetic control circuit 30. ing.

  The tracking error signal TE is given to the tracking servo circuit 40, and the tracking servo circuit 40 controls the biaxial actuator 24 of the optical pickup 20 in the X direction so that the recording track of the optical disc 1 is traced by the laser beam. ing.

  On the other hand, the focus error signal FE is given to the focus servo circuit 50A, and the biaxial actuator 24 of the optical pickup 20 is controlled in the Y-axis direction by the focus servo circuit 50A so that the laser beam is focused on the data recording surface of the optical disc 1. To be controlled. The focus servo circuit 50A includes a zero cross detector 51, a phase compensator 52, a switch 53, a focus driver 54, and a search signal generator 60A.

  The zero-cross detection unit 51 detects that the focus error signal FE has become zero (that is, is in focus) and outputs a zero-cross detection signal FZC. The zero cross detection signal FZC is given to the system control circuit 70A.

  The phase compensation unit 52 controls the operation of the biaxial actuator 24 so that the laser beam is always focused on the data recording surface of the optical disc 1 during servo operation (when data is read from the optical disc 1). The phase compensation processing of the focus error signal FE is performed.

  The switch 53 switches a signal to be given to the focus driver 54 in accordance with the mode signal MOD given from the system control circuit 70A. The switch 53 selects a search signal from the search signal generator 60A in the search operation mode such as when the optical disk 1 is activated, and in the servo operation mode such as when data is read after the optical disk 1 is activated, the phase compensation unit 52 is selected. The focus error signal FE having undergone phase compensation is selected and output. The focus driver 54 drives the biaxial actuator 24 of the optical pickup 20 in the Y direction in accordance with a signal given from the switch 53.

  The search signal generator 60A is for moving the biaxial actuator 24 up and down at a constant speed in the Y direction so that the laser beam emitted from the optical pickup 20 is focused on the data recording surface of the optical disc 1 in the search operation mode. A search signal is generated. The search signal generator 60A can generate triangular wave signals having different slopes in accordance with the control signals UP and DN.

  The search signal generator 60A includes constant current sources 61a and 61b that flow constant currents of different sizes (here, the current of the constant current source 61a is greater than the current of the constant current source 61b), Are the same as the constant current sources 61a and 61b, respectively, but have constant current sources 62a and 62b whose current directions are opposite. The constant current sources 61a and 61b are connected to the node N via switches 63a and 63b, respectively, and the constant current sources 62a and 62b are connected to the same node N via switches 64a and 64b, respectively.

  The switches 63a and 63b are individually controlled to be turned on / off by a control signal UP given from the system control circuit 70A. The switches 64a and 64b are individually controlled to be turned on / off by a control signal DN given from the system control circuit 70A.

  The node N is connected to a time constant circuit 65 composed of a resistor and a capacitor, and to an operational amplifier 66 constituting a voltage follower. The output side of the operational amplifier 66 is connected to the switch 53.

  The system control circuit 70A controls the entire optical disc driving device based on the focus information FOK given from the arithmetic control circuit 30, the zero cross detection signal FZC given from the zero cross detection unit 51 of the focus servo circuit 50A, and the like. . A vibration sensor 80 is connected to the system control circuit 70A for detecting whether or not the optical disk drive device receives external vibration. The vibration sensor 80 can be configured to output a vibration detection signal when, for example, a signal output from an acceleration sensor or the like exceeds a threshold value.

  Although not shown, the optical disk drive includes a sled mechanism that is controlled from the system control circuit 70A via a servo circuit. The sled mechanism is for sliding the entire optical pickup 20 in the X direction of the optical disc 1 over the entire recording area.

Next, the focus search operation in the optical disk drive of FIG. 1 will be described using FIGS.
First, the outline of the focus search operation will be described with reference to FIG.
When it is detected by a sensor (not shown) that the optical disk 1 is loaded on the spindle motor 10, the system control circuit 70A performs instruction control to rotate the spindle motor 10. Thereby, the optical disk 1 is rotationally driven in a certain direction.

  At the same time, the system control circuit 70A instructs the thread mechanism to move the optical pickup 20 to the TOC area where the TOC information for managing the data area of the optical disc 1 is recorded. As a result, the entire optical pickup 20 moves to just below the TOC area of the optical disc 1.

  Next, a mode signal MOD for designating a search operation is output from the system control circuit 70A to the focus servo circuit 50A, and the output side of the search signal generator 60A is connected to the focus driver 54 via the switch 53.

  Furthermore, the system control circuit 70A outputs a control signal UP to the search signal generator 60A for initial search-up processing, and sets a timer for monitoring the output time of the control signal UP. At this time, the control signal UP is set so that both the switches 63a and 63b are simultaneously turned on.

  The switches 63a and 63b are turned on by the control signal UP, and currents from the constant current sources 61a and 61b simultaneously flow into the time constant circuit 65 connected to the node N. As a result, the potential of the node N rises from 0 at a high speed.

  The potential of the node N is supplied as a search signal to the focus driver 54 through the operational amplifier 66 and the switch 53, and the focus driver 54 drives the biaxial actuator 24 of the optical pickup 20. As a result, the objective lens 24a rises from the reference position corresponding to the potential 0 of the node N at the same high speed as that of the potential of the node N, and approaches the data recording surface of the optical disc 1.

  For example, as shown in FIG. 2A, when the just focus position is lower than the reference position, the focus error signal FE output from the arithmetic control circuit 30 during the initial search up process does not become zero. Accordingly, the zero cross detection signal FZC is not output from the zero cross detection unit 51 of the focus servo circuit 50A. For this reason, when the lens position reaches the highest position (the closest point to the optical disc 1), the timer for monitoring the output time of the control signal UP for the initial search-up process times out.

  Due to the time-over, the system control circuit 70A checks whether vibration is detected by the vibration sensor 80 or not. If no vibration is detected, the system control circuit 70A outputs a control signal DN for search-down processing, and sets a timer for monitoring the output time of the control signal DN. At this time, the control signal DN is set so that both the switches 64a and 64b are simultaneously turned on.

  The switches 64a and 64b are turned on by the control signal DN, and currents simultaneously flow from the time constant circuit 65 connected to the node N to the constant current sources 62a and 62b. As a result, the potential of the node N decreases at a high speed.

  Due to the decrease in the potential of the node N, the objective lens 24 a is lowered at the same high speed as the decrease rate of the potential of the node N and is separated from the data recording surface of the optical disc 1. When the objective lens 24a reaches the just focus position, the zero-cross detection signal FZC is output from the zero-cross detection unit 51. As a result, the system control circuit 70A temporarily stops the timer, temporarily stops the output of the control signal DN, and further switches the switch 53 to the servo operation side by the mode signal MOD. When the servo pull-in is successful, the arithmetic control circuit 30 outputs focus information FOK indicating that the focus is correctly achieved. As a result, the focus search operation ends, and the next data reading process or the like is started.

  On the other hand, as shown in FIG. 2B, when the objective lens 24a reaches the just focus position and is switched to the servo operation side by the zero-cross detection signal FZC output from the zero-cross detection unit 51, vibration occurs. If the lens position is greatly shaken, servo pull-in will not succeed and focus information FOK will not be output. For this reason, the search-down process is resumed.

  When the lens position reaches the lowest position and the timer expires, the system control circuit 70A stops outputting the control signal DN and determines whether or not the vibration sensor 80 detects vibration. When vibration is detected, the system control circuit 70A outputs a control signal UP for search-up processing at a medium speed, and sets a timer for monitoring the output time of the control signal UP. At this time, the control signal UP is set to turn on only the switch 63a.

  The switch 63a is turned on by the control signal UP, and current flows from the constant current source 61a into the time constant circuit 65 connected to the node N. As a result, the potential of the node N rises at a medium speed. The objective lens 24a rises at the same middle speed as the potential rise of the node N, and approaches the data recording surface of the optical disc 1 from the lowest position.

  When the lens position reaches the just focus position in the ascending process of the objective lens 24a, the switch 53 is switched to the servo operation side by the zero cross detection signal FZC output from the zero cross detector 51. Even at this time, if the lens position is greatly shaken by vibration, the servo pull-in is not successful and the focus information FOK is not output. Further, even if the focus information FOK is temporarily output, the servo is pulled out by vibration and the output stops. Thereby, the search-up process is resumed.

  When the lens position reaches the top and the timer expires, the system control circuit 70A stops outputting the control signal UP and determines whether or not the vibration sensor 80 detects vibration. When vibration is detected, the system control circuit 70A outputs a control signal DN for search-down processing at low speed, and sets a timer for monitoring the output time of the control signal DN. At this time, the control signal DN is set to turn on only the switch 64b.

  The switch 64b is turned on by the control signal DN, and a current flows from the time constant circuit 65 connected to the node N to the constant current source 62b. As a result, the potential of the node N drops at a slow speed. The objective lens 24a descends at the same slow speed as the potential of the node N and gradually moves away from the data recording surface of the optical disc 1.

  When the lens position reaches the just focus position in the lowering process of the objective lens 24a, the switch 53 is switched to the servo operation side by the zero cross detection signal FZC output from the zero cross detection unit 51. At this time, since the descending speed of the objective lens 24a is slow, it is possible to capture the just focus position relatively accurately. Thus, when the servo pull-in is successful, the focus search operation ends, and the next process such as data read processing is started.

  Next, the general flow of the focus search process by the system control circuit 70A will be described with reference to FIG.

  The system control circuit 70A first performs an initial search-up process (step S10: details of the process will be described later). If the process is successful (step S10; successful), the focus search process ends. When the initial search-up process fails (step S10; failure), the system control circuit 70A determines the presence or absence of vibration (step S21).

  If no vibration is detected (step S21; None), the system control circuit 70A sets the search speed to the maximum (step S22), and proceeds to the search-down process of step S30. When vibration is detected (step S21; present), the system control circuit 70A checks whether or not the currently set search speed is the lowest (step S23).

  If the search speed is the lowest (step S23; yes), the process proceeds directly to step S30. If the search speed is not the lowest (step S23; no), the search speed is lowered by one step (step S24) and the process proceeds to step S30. .

  In step S30, the system control circuit 70A performs a search down process described later. If the process is successful (step S30; successful), the focus search process ends. If the search-down process fails (step S30; failure), the system control circuit 70A determines the presence or absence of vibration (step S41).

  If no vibration is detected (step S41; no), the search speed is set to the maximum (step S42), and the process proceeds to the search-up process in step S50. When vibration is detected (step S41; present), the system control circuit 70A checks whether or not the currently set search speed is the lowest (step S43).

  If the search speed is the lowest (step S43; yes), the process proceeds directly to step S50. If the search speed is not the lowest (step S43; no), the search speed is lowered by one step (step S44) and the process proceeds to step S50. .

  In step S50, the system control circuit 70A performs a search-up process described later. If the process is successful (step S50; successful), the focus search process ends. If the search-up process fails (step S50; failure), the system control circuit 70A determines the presence or absence of vibration (step S21).

  If vibration is not detected (step S21; none), the system control circuit 70A sets the search speed to the maximum (step S22) and returns to the search-down process in step S30. When vibration is detected (step S21; present), the system control circuit 70A checks whether or not the currently set search speed is the lowest (step S23).

  If the search speed is the lowest (step S23; yes), the process returns to step S30 as it is. If the search speed is not the lowest (step S23; no), the search speed is lowered by one step (step S24) and the process returns to step S30. .

FIG. 4 is a flowchart of the initial search-up process in FIG.
In the initial search-up process, the system control circuit 70A sets the search speed to the maximum (step S11), sets a timer corresponding to the search speed (step S12), and then searches for the search-up corresponding to the search speed. A control signal UP is output (step S13). As a result, the objective lens 24a of the optical pickup 20 approaches the data recording surface of the optical disc 1 at the set search speed.

  The system control circuit 70A detects the just focus by monitoring the zero cross detection signal FZC output from the focus servo circuit 50A (step S14). When the just focus is detected (step S14; Yes), the system control circuit 70A temporarily stops the timer and switches to the servo operation (step S15).

  If the servo pull-in is successful in the servo operation (step S16; Yes), this initial search-up process ends successfully. When the servo pull-in is not successful (step S16; No), the system control circuit 70A restarts the timer operation, switches to the search operation (step S17), and returns to the just focus detection process in step S14. .

  On the other hand, when the just focus is not detected (step S14; No), the detection of the just focus in step S14 is continued while the time is not over (step S18; No). When the time is over (step S18; Yes), this initial search-up process ends in failure.

FIG. 5 is a flowchart of the search-down process in FIG.
In the search-down process, the system control circuit 70A sets a timer corresponding to the set search speed (step S31), and then outputs a search-down control signal DN corresponding to the search speed (step S32). Thereby, the objective lens 24a of the optical pickup 20 moves away from the data recording surface of the optical disc 1 at the set search speed.

  The system control circuit 70A detects the just focus by monitoring the zero cross detection signal FZC output from the focus servo circuit 50A (step S33). When the just focus is detected (step S33; Yes), the system control circuit 70A temporarily stops the timer and switches to the servo operation (step S34).

  If the servo pull-in is successful in the servo operation (step S35; Yes), this search-down process is completed successfully. If the servo pull-in is not successful (step S35; No), the system control circuit 70A restarts the timer operation, switches to the search operation (step S36), and returns to the just focus detection process in step S33. .

  On the other hand, when the just focus is not detected (step S33; No), while the time is not over (step S37; No), the detection of the just focus in step S33 is continued. When the time is over (step S37; Yes), this search-down process ends in failure.

FIG. 6 is a flowchart of the search-up process in FIG.
In the search-up process, the system control circuit 70A sets a timer corresponding to the set search speed (step S51), and then outputs a search-up control signal UP corresponding to the search speed (step S52). As a result, the objective lens 24a of the optical pickup 20 approaches the data recording surface of the optical disc 1 at the set search speed.

  The system control circuit 70A detects the just focus by monitoring the zero cross detection signal FZC output from the focus servo circuit 50A (step S53). When the just focus is detected (step S53; Yes), the system control circuit 70A temporarily stops the timer and switches to the servo operation (step S54).

  If the servo pull-in is successful in the servo operation (step S55; Yes), this search-up process is completed successfully. When the servo pull-in is not successful (step S55; No), the system control circuit 70A restarts the timer operation, switches to the search operation (step S56), and returns to the just focus detection process of step S53. .

  On the other hand, when the just focus is not detected (step S53; No), while the time is not over (step S57; No), the just focus detection in step S53 is continued. If the time is over (step S57; Yes), this search-up process ends in failure.

  As described above, the optical disk drive according to the present embodiment checks the presence or absence of vibration when the focus search fails in the search operation of search-up or search-down, and if vibration is detected, The search speed is slowed down. As a result, the probability of a successful focus search can be increased even during vibration.

  Further, when no vibration is detected, the search speed in the next search operation is set to the highest speed. Thereby, when there is no vibration, the search operation can be performed at the highest search speed, so that the focus search can be performed in a short time.

In addition, this invention is not limited to the said embodiment, The following various deformation | transformation are possible.
(A) The search signal generator 60A is configured to generate search signals of three types of search speeds by the control signals UP and DN, but generates search signals of two types or four or more types of search rates. It can also be configured as follows. The specific circuit configuration of the search signal generator 60A is only an example, and any circuit that can generate signals at a plurality of search speeds may be used.

(B) The search signal generator 60A searches at the highest search speed when no vibration is generated. However, even if the search speed is not the highest search speed, the search signal generator 60A has a search speed used for a normal focus search. Also good.
(C) In the system control circuit 70A, the next search speed is determined based on the presence or absence of vibration at the time when the search up process or the search down process fails. The next search speed may be determined based on whether or not there is.

(D) If there is vibration when the focus search fails, the next search speed is reduced. However, when the focus search fails, the next search speed is reduced regardless of the presence or absence of vibration. Anyway. This is because even if there is no vibration, for example, the focus search may fail due to slight deformation of a CD or the like. In such a case, lowering the search speed is effective for making the focus search successful.
(E) Although the optical disk drive device dedicated to data reading has been described, the present invention can be similarly applied to an optical disk drive device capable of writing data. However, it is practically difficult to write data under environmental conditions with a lot of vibration such as in-vehicle use because there is a high risk of writing errors.

DESCRIPTION OF SYMBOLS 1 Optical disk 10 Spindle motor 20 Optical pick-up 30 Operation control circuit 40 Tracking servo circuit 50A Focus servo circuit 51 Zero cross detection part 52 Phase compensation part 53, 63a, 63b, 64a, 64b Switch 54 Focus driver 60A Search signal generation part 61a, 61b, 62a, 62b Constant current source 65 Time constant circuit 66 Operational amplifier 70A System control circuit 80 Vibration sensor

Claims (2)

An optical pickup that irradiates the data recording surface of the optical disc with illumination light through a lens, detects the reflected light, and converts it into an electrical signal;
A calculation means for generating a focus error signal indicating a focus state of the irradiation light based on the electrical signal;
A focus servo that controls the position of the lens to adjust the focus of the irradiation light and tracks the position of the lens based on the focus error signal when the focus of the irradiation light coincides with the data recording surface of the optical disc. Means,
Vibration detecting means for detecting vibrations applied from the outside;
In an optical disk drive comprising:
The focus servo means includes
A search signal generator capable of generating a plurality of search signals for driving the lens at different speeds in a predetermined direction in order to adjust the focal position of the optical pickup;
In the initial focus position search, the search signal generator generates a search signal for driving the lens at a predetermined speed to drive the lens, and when the focus position search fails, the vibration detection means sets a constant value. When a vibration exceeding the predetermined value is detected, a search signal for sequentially driving the lens at a low speed is generated to search the focal position. When a vibration exceeding a certain value is not detected, the search signal of the predetermined speed is generated. A control unit that repeats the focus position search using ,
An optical disk drive device comprising: In an optical disc driving apparatus for reading data on an optical disc by irradiating the optical disc with a recording light through a lens, detecting the reflected light and converting it into an electrical signal, the focus of the irradiation light is the data recording surface A focus search control method for controlling the position of the lens based on a plurality of search signals having different speeds to match
In the initial focus position search, the lens is driven using a search signal of a predetermined speed, and when a focus position search fails, a vibration exceeding a certain value is detected. Generate a signal to search for the focal position, and if no vibration exceeding a certain value is detected, repeat the focal position search using the search signal of the predetermined speed,
A focus search control method characterized by the above.

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