JP5000163B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disk device, and more particularly to transfer control of an optical pickup.

  Conventionally, in an optical disc apparatus, a seek operation is performed by transferring an optical pickup in a radial direction of the optical disc by a stepping motor.

  4 and 5 show the configuration of the optical disc apparatus and the configuration of the transfer mechanism disclosed in the prior art described below. The optical pickup 310 has a semiconductor laser (LD), emits laser light modulated in accordance with recording data, records data on the optical disk 10, and irradiates a laser beam with reproduction power to reflect light from the optical disk 10. Is received and a reproduction signal is generated.

  The decoder 320 decodes the reproduction signal from the optical pickup 310, generates an address signal or the like, and supplies it to the control unit 330.

  The control unit 330 includes a CPU, a ROM, a RAM, and the like, and controls a seek operation. Specifically, when a seek operation command including a target address corresponding to the transfer destination of the optical pickup 310 is received from a host device such as a personal computer, the number of pulses applied to the stepping motor 100 is calculated and supplied to the controller 340. The controller 340 supplies a drive control signal to the driver 350 based on a command from the control unit 330. The driver 350 controls the rotation speed and rotation speed of the stepping motor 100 according to the drive control signal.

  As shown in FIG. 5, the stepping motor 100 is provided with a lead screw 110 in which spiral grooves are formed at a constant pitch P. The lead screw 110 is attached in parallel with the radial direction of the optical disc 10. The optical pickup 310 is arranged so as to be movable along the groove of the lead screw 110 and moves in the radial direction of the optical disk 10 by one pitch P of the lead screw 110 every time the stepping motor 100 makes one rotation.

  In such a configuration, the control unit 330 calculates the difference between the current address supplied from the decoder 320 when the seek operation is completed and the target address received from the host device when the seek operation starts, and the calculated displacement amount is When the allowable amount is exceeded, it is determined that the stepping motor 100 is out of step, and the rotation speed of the stepping motor 100 is decreased. Here, “step-out” refers to a phenomenon in which the stepping motor 100 does not rotate even when a pulse voltage is applied because the torque of the stepping motor 100 is insufficient due to an increase in the pulse frequency applied to the stepping motor 100 or the like.

JP 2003-100041 A

  However, the problem of the transfer mechanism includes not only the stepping motor 100 out of step, but also a problem of so-called “tooth skip” in which the teeth 310 a provided in the optical pickup 310 and the lead screw 110 are disengaged. Even if a jump occurs, there is a problem that a divergence occurs between the target address and the current address. Note that tooth skipping is considered to occur mainly due to wear or damage of the tooth portion 310a due to operation over time or impact, vibration, or the like, and can occur in the same manner when not only the stepping motor 100 but also a DC motor is used. .

  An object of the present invention is to provide an apparatus capable of efficiently detecting an abnormality such as tooth skipping between an optical pickup and a lead screw and thereby preventing a deviation between a target address and a current address.

The present invention includes a motor, an optical pickup that irradiates an optical disc with laser light, a transfer mechanism that engages with the motor and moves the optical pickup in the radial direction of the optical disc by rotation of the motor, and the optical pickup A focus servo means for controlling the focus, and in response to a servo signal from the focus servo means, it is determined that an abnormality has occurred in the transfer mechanism when the focus control by the focus servo means is interrupted, and the light by the transfer mechanism And control means for interrupting the transfer of the pickup and reducing the rotation speed of the motor to restart the transfer .

The present invention also includes a motor, an optical pickup that irradiates an optical disk with laser light, a transfer mechanism that engages with the motor and moves the optical pickup in a radial direction of the optical disk by rotation of the motor, A focus servo unit that generates a focus error signal from a reproduction signal of the optical pickup and performs focus control according to the focus error signal, and an abnormality occurs in the transfer mechanism when the level of the focus error signal exceeds a predetermined threshold value. Control means for stopping the transfer of the optical pickup by the transfer mechanism by judging that it has occurred, and reducing the rotation speed of a spindle motor that rotationally drives the optical disc to resume the transfer .

  According to the present invention, when the focus servo is interrupted or the abnormality of the focus error signal level is detected, it is determined that an abnormality (tooth skipping or the like) has occurred in the transfer mechanism, and the transfer of the optical pickup is interrupted. It is possible to prevent wear and damage of the tooth portion due to occurrence of deviation from the address and tooth skipping.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected about the same member as the conventional apparatus shown in FIG.

  As shown in FIG. 1, the configuration of the optical disk apparatus of this embodiment is almost the same as that of the conventional apparatus shown in FIG. 4, and a seek operation start command from a host device such as a personal computer is supplied to the control unit 330. . The controller 330 supplies a control signal to the controller 340, and the stepping motor 100 is rotationally controlled by the controller 340 and the driver 350. As shown in FIG. 5, the optical pickup 310 is connected to the lead screw 110 via the tooth portion 310 a and moves in the radial direction of the optical disc 10 by the rotation of the lead screw 110. The optical pickup 310 records data by irradiating the optical disk 10 rotated by the spindle motor 11 with a recording power laser beam or irradiates a reproducing power laser beam to reproduce the recorded data. A reproduction signal from the optical pickup 310 is supplied to the decoder 320, and the decoder 320 decodes the reproduction signal and supplies decoded data and address data to the control unit 330.

  On the other hand, the optical pickup 310 is driven and controlled in the focus direction of the optical disc 10 by the focus servo 12 and is controlled in the tracking direction of the optical disc 10 by a tracking servo (not shown). The focus servo 12 and the tracking servo move the objective lens of the optical pickup 310 to the focus coil so as to eliminate the focus error and the tracking error according to the focus error signal FE and the tracking error signal TE generated from the reproduction signal of the optical pickup 310, respectively. In addition, servo control is performed by electromagnetic driving with a tracking coil. A method for generating the focus error signal and the tracking error signal is well known, and details thereof are omitted.

  In the present embodiment, the focus servo 12 supplies a servo signal to the focus coil of the optical pickup 310 for servo control and supplies the servo signal to the control unit 330. The focus servo 12 performs servo control by generating a servo signal that cancels the focus error signal FE if the level of the focus error signal FE is within a predetermined range, but when the level of the focus error signal FE exceeds the upper limit value, Determines that focus servo is not possible and interrupts focus servo. The control unit 330 determines whether or not the focus servo 12 interrupts the focus servo during the macro seek based on the servo signal, and the focus servo is interrupted and the focus control of the optical pickup 310 is turned off (this is the focus down). This state is detected as a state in which tooth skipping has occurred. When tooth skip occurs, the target address cannot be reached. In other words, in a normal case, a certain relationship is established between the number of pulses supplied to the stepping motor 100 and the amount of transport of the optical pickup 310 that is actually transported. Therefore, the optical pickup is counted by counting the number of input pulses. The transfer amount of 310 can be calculated. Specifically, the transfer amount of the optical pickup 310, that is, the address after the transfer, can be defined by counting the input pulses to the stepping motor 100 with the stepper pointer. For example, one microstep is set to 1/256 rotation of the stepping motor 100, and the optical pickup 310 is transported by 7.8 μm in one microstep. However, if tooth skipping occurs, the relationship between the microstep amount and the transfer amount is lost, and a difference occurs between the position of the optical pickup obtained from the stepper pointer and the actual position of the optical pickup 310. Then, it should have reached the target address, but in reality, it exists at a position different from the target address. Therefore, when it is determined that tooth skipping has occurred, the control unit 330 executes a predetermined process to eliminate the divergence between the target address and the current address due to tooth skipping.

  FIG. 2 shows a processing flowchart of the present embodiment. First, when a seek operation start command is received from the host device, the current address is read (S101), the tracking servo is turned off (S102), and the stepping motor 100 is driven to start macro seek (S103). Here, the macro seek refers to transferring the optical pickup 310 itself in the radial direction of the optical disc 10. On the other hand, the micro jump described later refers to moving only the objective lens in the track direction without transferring the optical pickup 310 itself. In the macro seek, the controller 330 calculates the transfer distance from the current address to reach the target address given from the host device, calculates the number of pulses according to the transfer distance, and drives the stepping motor 100. The rotation angle of the stepping motor 100 is defined by the number of pulses, and the rotation speed is defined by the pulse frequency.

  After the macro seek is started and the transfer of the optical pickup 310 is started, the control unit 330 determines whether or not focus down has occurred based on the servo signal from the focus servo 12 (S104). The focus down occurs when the level of the focus error signal FE exceeds a predetermined range as described above. When tooth skip occurs, the teeth 310a provided in the optical pickup 310 and the lead screw 110 are engaged. A focus error occurs because the teeth 310a provided on the optical pickup 310 are out of alignment and ride on the groove of the lead screw 110 and the objective lens of the optical pickup 310 moves steeply in the focus direction due to the impact and vibration. It can be considered that the level of the signal FE has increased. Therefore, the control unit 330 determines that tooth skipping has occurred when focus down occurs during macro seeking (S105).

  When a tooth jump occurs, a deviation occurs from the target address. Therefore, when the control unit 330 determines that the tooth jump occurs, the macro seek that started in S103 is interrupted (S106), that is, the driving of the stepping motor 100 is interrupted. The rotational speed (rotational speed) of the spindle motor 11 is reduced (S107). For example, when the optical disk 10 is rotationally driven by the spindle motor 11 at 8 times speed, the speed is reduced to 6 times speed or 4 times speed. The reason why the rotational speed of the spindle motor 11 is decreased is to suppress vibration that is a cause of tooth skipping. If the optical disk 10 has an eccentric center of gravity, the spindle motor 11 vibrates during high-speed rotation, and the vibration is transmitted to a transfer mechanism such as the optical pickup 310, the tooth portion 310a, the lead screw 110, and the like, which causes tooth skipping. Therefore, if the rotation speed of the spindle motor 11 is decreased, vibration can be suppressed. Further, the controller 330 not only decreases the rotation speed of the spindle motor 11, but also changes the drive characteristic (profile) of the stepping motor 100 from the normal profile to the low profile (S108). After the rotational speeds of the spindle motor 11 and the stepping motor 100 are reduced, the focus servo is turned on again, the tracking servo is turned on to read the current address (S101), and the macro seek is started again (S103).

  When the macro seek is interrupted in S106, the current address of the optical pickup 310 may be reset by transferring to the innermost periphery of the optical disc 10 in addition to maintaining the optical pickup 310 at the interruption position. That is, the optical pickup 310 is transferred to the innermost periphery, the current address is reset to 0 (when the innermost address is set to 0), and the macro seek is performed again from this point toward the target address given from the host device. Start operation. Then, it is determined again whether or not focus down has occurred (S104).

  On the other hand, if focus down has not occurred, the controller 330 determines that the optical pickup 310 has been normally transferred, ends macro seek (S109), turns on the tracking servo, and performs servo control (S110). Thereafter, a normal resee process is executed (S111). In the normal re-seek process, the macro seek is executed again according to the remaining distance to the target address, or the micro jump for driving only the objective lens is executed.

  FIG. 3 shows an example of the low profile in S108. The horizontal axis represents the number of pulses supplied from the driver 350, and the vertical axis represents the rotation speed of the stepping motor 100. In the figure, a is a normal profile and b in the figure is a low profile. In the normal profile, the maximum rotation speed is N1, but in the low profile, the maximum rotation speed is N2. Further, the acceleration in the low profile is smaller than that in the normal profile. Therefore, tooth skipping can be prevented by changing to a low profile.

  As described above, in the present embodiment, the tooth skip of the optical pickup 310 is detected by detecting focus down and predetermined processing is executed, so that the optical pickup 310 is reliably sought to the target address commanded by the host device. be able to. Further, it is possible to prevent the tooth portion 310a from being worn or damaged due to tooth skipping.

  In this embodiment, when tooth skipping is detected, the rotation speed of the spindle motor 11 is decreased and the rotation speed of the stepping motor 100 is decreased and the macro seek is performed again. However, only the rotation speed of the spindle motor 11 is detected. May be reduced. Further, the macro seek may be executed again while changing other conditions.

  Moreover, although the case of the stepping motor 100 is shown in the present embodiment, the present invention can be similarly applied to the case of driving with a DC motor.

  In this embodiment, focus down is detected based on the servo signal from the focus servo 12. However, a comparison circuit for comparing the level of the focus error signal with a predetermined threshold is provided, and the comparison result from the comparison circuit is provided. Focus down may be detected based on the above. The focus servo 12 may have the comparison circuit. The comparison circuit compares the level of the focus error signal FE with a predetermined threshold value, and the level of the focus error signal FE exceeds the predetermined threshold value. In this case, the servo control may be interrupted and an abnormal signal may be supplied to the control unit 330. The control unit 330 may detect the occurrence of tooth skipping by the abnormal signal supplied from the comparison circuit of the focus servo 12 and interrupt the macro seek operation.

  Further, in the present embodiment, tooth skipping is detected by focusing down. However, when the stepping motor 100 is used, the positional deviation between the target address and the current address as shown in the prior art in parallel with the tooth skip detection. The amount may be calculated, and the step-out of the stepping motor 100 may be detected from this positional deviation amount. In this case, after finishing the macro seek in S109, the current address is read, the target address supplied from the host device is compared with the current address, and if there is a divergence exceeding a predetermined allowable value, a step-out has occurred. Therefore, the processes of S107 and S108 are performed, and the macro seek is executed again.

It is a block diagram of the optical disk apparatus in embodiment. It is a processing flowchart of an embodiment. It is explanatory drawing of the low profile of embodiment. It is a block diagram of a conventional apparatus. It is transfer mechanism explanatory drawing of a conventional apparatus.

Explanation of symbols

  10 optical disk, 12 focus servo, 100 stepping motor, 310 optical pickup, 320 decoder, 330 control unit, 340 controller, 350 driver.

Claims (3)

A motor,
An optical pickup for irradiating an optical disc with laser light;
A transfer mechanism that engages with the motor and transfers the optical pickup in the radial direction of the optical disc by rotation of the motor;
Focus servo means for controlling the focus of the optical pickup;
In response to a servo signal from the focus servo means, when focus control by the focus servo means is interrupted, it is determined that an abnormality has occurred in the transfer mechanism, and transfer of the optical pickup by the transfer mechanism is interrupted, and the motor Control means for reducing the rotation speed of the machine and restarting the transfer ,
An optical disc apparatus comprising: A motor,
An optical pickup for irradiating an optical disc with laser light;
A transfer mechanism that engages with the motor and transfers the optical pickup in the radial direction of the optical disc by rotation of the motor;
A focus servo means for generating a focus error signal from the reproduction signal of the optical pickup and performing focus control according to the focus error signal;
When the level of the focus error signal exceeds a predetermined threshold value, it is determined that an abnormality has occurred in the transfer mechanism, the transfer of the optical pickup by the transfer mechanism is interrupted, and the rotation speed of the spindle motor that rotationally drives the optical disk Control means for reducing the flow and restarting the transfer ,
An optical disc apparatus comprising: The apparatus according to claim 1,
The optical disk apparatus according to claim 1, wherein the abnormality is skipping of the transfer mechanism.

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