JP5353680B2 - Optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk device with which the position control of an optical pickup is accurately performed, and moreover, of which the motion has high-quality, without the use of a detection means to detect the initial position of the optical pickup. <P>SOLUTION: In the optical disk device, a drive pulse signal with which the output torque of a drive motor 52 becomes smaller than the moment due to a drive force transmission section 72 is sent to a drive motor 51, when the initial position of the optical pickup 3 is to be detected. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an optical disc apparatus that reads and / or writes information on an optical disc that is a recording medium.

  An optical disk device reads and / or writes information by inserting an optical disk, which is a recording medium, and irradiating light onto an information recording surface of the optical disk. A conventional optical disc apparatus will be described with reference to the drawings. FIG. 7 is a schematic plan view of a conventional optical disc apparatus. In the optical disc apparatus, the optical pickup 93 is supported by a pair of guide shafts 94, 94 provided in the traverse chassis 91, and is guided by the guide shafts 94, 94 to approach and separate from the turntable 92.

  The optical pickup 93 includes a rack piece 934 that meshes with a lead screw 951 that is rotatably supported by the traverse chassis 91, and the lead screw 951 is rotationally driven by a drive motor 952 that is fixed to the traverse chassis 91. The rack piece 934 is sent to the lead screw 951, the optical pickup 93 is guided by the guide shaft 94, and approaches / separates from the turntable 92. (Refer to Unexamined-Japanese-Patent No. 2000-156054, 2007-234108 etc.).

  In recent years, optical disc apparatuses are required to read and / or write information (hereinafter sometimes referred to as reading) on different types of optical discs such as CD, DVD, and BD (Blu-ray Disc). When performing reading or the like on different optical disks, the wavelength of light used for reading or the like differs depending on the type of optical disk to be read or the optical system is different, so it is necessary to determine the type of the inserted optical disk. . In general, an optical disc is provided with an area in which disc-specific information called a Burst Cutting Area (BCA area) is written in the innermost periphery regardless of the type. The optical disc apparatus can determine the type of the inserted optical disc by reading the information in the BCA area.

  When the BCA area of the optical disk is placed on the turntable 92, the distance from the center of the turntable 92 is constant. Therefore, by accurately controlling the position of the optical pickup 93 with respect to the turntable 92, the optical pickup 93 can accurately read the information written in the BCA area of the optical disc placed on the turntable 92. . In the optical disc apparatus, when the position control of the optical pickup 93 is performed, the initial position of the optical pickup 93 is first determined, and then the position control is performed based on the positional relationship between the initial position and the turntable 92. Usually, in the optical disk apparatus, the initial position is set to the stroke end (the one closer to or far from the turntable 92) of the optical pickup 93.

  In the optical disc apparatus, immediately after the power is turned on or immediately after a new optical disc is inserted, the optical pickup 93 is moved to the initial position of the stroke end, and position control is performed using that position as the origin. As shown in FIG. 7, the traverse chassis 91 is provided with an optical pickup detection means 96 provided with a limit switch, a proximity switch, an optical sensor, or the like at the stroke end closer to the turntable 92. When the optical pickup 93 is moved to the stroke end, the optical pickup detection means 96 detects the optical pickup 93. When the optical pickup detecting means 96 detects the optical pickup 93, the drive motor 952 is stopped, and the movement of the optical pickup 93 to the initial position is completed.

  In addition, there is a method of adjusting the initial position using the feature of the stepping motor which is the drive motor 952. A pulse signal is input to the drive motor 952, and a force is generated to rotate the lead screw 951. The optical pickup 93 is moved to the stroke end (here, farther from the turntable 92) and brought into contact with the traverse chassis 91. At this time, since the optical pickup 93 comes into contact with the traverse chassis 91 and is forcibly stopped, the movement of the rack piece 934 is also stopped, and a force acts on the drive motor 952 in a forcible direction. At this time, the drive motor 952 is in a so-called step-out state in which the pulse signal is input but does not move. It is detected that the optical pickup 93 has moved to the initial position when the drive motor 952 is in a step-out state (see JP 2007-265525 A).

  With this configuration, the switch for detecting the initial position of the optical pickup 93 or the like, the optical pickup detection means 96 configured by a substrate, wiring, or the like connected to the switch or the like can be omitted. In addition, it is not necessary to provide a switch or the like and a mounting area for a substrate, wiring, and the like, and the size can be reduced accordingly.

  Also, in an optical disc apparatus that detects the initial position by moving the optical pickup 93 to the straw end, the one that controls the output of the stepping motor to reduce the torque of the stepping motor to a predetermined torque at a predetermined timing. It has been proposed (Japanese Patent Laid-Open No. 2007-323746). The torque output is adjusted by controlling the voltage of the input pulse signal.

  By controlling the driving of the stepping motor in this way, when the optical pickup 93 comes into contact with the stopper, the rotational torque of the lead screw 951 can be reduced, and the rack piece 934 can be prevented from skipping teeth. Is possible.

JP 2000-156054 A JP 2007-234108 A JP 2007-265525 A JP 2007-323746 A

  When the optical pickup 93 reaches the stroke end, a pulse signal is input to the drive motor 952, and the lead screw 951 receives a force in a direction in which it continues to rotate. The rack piece 934 is attached to the optical pickup 93 via an elastic member (plate spring). When the rotational force of the lead screw 951 is larger than the force for stopping the lead screw 951 of the rack piece 934, the rack piece 934 is provided. So-called tooth jumping occurs in which the claws jump out of the groove of the lead screw 951. When tooth jump occurs, abnormal noise and vibration occur. Further, if tooth skipping continues, the initial position cannot be detected, and the position control of the optical pickup 93 may not be performed. Furthermore, the claw of the rack piece 934 may be scraped into the spiral groove of the lead screw 951, making it easier to skip teeth.

  In order to suppress the occurrence of tooth skipping, Japanese Patent Application Laid-Open No. 2007-265525 uses rack engagement amount adjusting means for reducing the engagement amount of the rack with the lead screw groove when the optical pickup reaches the stroke end. . However, the optical disk apparatus having this configuration must be provided with a meshing amount adjusting means, which complicates the configuration of the optical disk apparatus.

  In the case of the invention described in Japanese Patent Application Laid-Open No. 2007-323746, if the approximate position of the optical pickup 93 is not known, it is difficult to set a predetermined timing for reducing the driving torque of the motor. Further, the optical pickup 93 is not always stopped at the same position. In this case, the optical pickup 93 may come into contact with the stopper before the driving torque is reduced. Further, a circuit for controlling the voltage of the input pulse signal is required, and the configuration of the optical disc apparatus is complicated.

  Accordingly, an object of the present invention is to provide an optical disc apparatus that can accurately control the position of the optical pickup without using a detecting means for detecting the initial position of the optical pickup.

It is another object of the present invention to provide an optical disc apparatus that suppresses occurrence of abnormal noise, vibration, and the like due to tooth skipping when detecting the initial position of an optical pickup, and has high operation quality.

  In order to achieve the above object, the present invention provides an optical pickup supported so as to be slidable in the radial direction of an optical disc, a lead screw arranged so that its axis is parallel to the sliding direction of the optical pickup, and the lead screw. A drive motor that is a stepping motor, a driving force transmission unit that is coupled to the optical pickup via an elastic member, and meshes with the lead screw, and is disposed in the vicinity of the stroke end of the optical pickup, An optical disc apparatus comprising a regulating means for preventing sliding of the optical pickup, and a control means for sending and driving a pulse signal to the drive motor, wherein the control means detects the initial position of the optical pickup, The output torque of the drive motor is controlled by the force that suppresses the rotation of the lead screw by the drive force transmission unit. Characterized in that it sends a drive pulse signal to be smaller than the moment acting on the lead screw to the drive motor.

  According to this configuration, when detecting the initial position of the optical pickup, the drive motor outputs an output torque smaller than the moment due to the force of pressing the lead screw by the driving force transmitting portion of the optical pickup. Accordingly, when detecting the initial position of the optical pickup, the drive motor can be stepped out quickly and reliably when the initial position of the optical pickup is detected.

  As a result, the initial position of the optical pickup can be detected accurately and quickly. Further, it is possible to suppress the driving force transmission unit from skipping from the lead screw, and it is possible to suppress generation of abnormal noise and vibration due to tooth skipping. As a result, it is possible to provide an optical disc apparatus with high operation quality.

  In the above configuration, the control means, after exciting and holding the drive motor, sends a start pulse signal capable of self-start to the drive motor, and after the drive motor is driven and the optical pickup starts moving, the drive motor The frequency of the drive pulse signal is set so that the output torque of the drive motor is smaller than the moment acting on the lead screw by the force that suppresses the rotation of the lead screw by the drive force transmission unit. Then, the drive pulse signal having the adjusted frequency may be sent to the drive motor.

  In the above configuration, the control unit includes a counting unit that counts the number of pulses of the pulse signal sent from the control unit to the drive motor, and the control unit sets the counting unit when the detection of the initial position of the optical pickup is completed. It may be reset.

  According to the present invention, it is possible to provide an optical disc apparatus capable of accurately controlling the position of the optical pickup without using a detection means for detecting the initial position of the optical pickup.

  In addition, according to the present invention, when detecting the initial position of the optical pickup, it is possible to suppress the generation of abnormal noise, vibration, etc. due to tooth skipping, and to provide an optical disc apparatus with high operation quality.

1 is a schematic diagram of an optical disc apparatus according to the present invention. It is the top view to which the driving force transmission part of the optical disk apparatus shown in FIG. 1 was expanded. FIG. 3 is an enlarged view of a driving force transmission unit of the optical disc apparatus shown in FIG. FIG. 3 is an enlarged view when an optical pickup used in the optical disc apparatus shown in FIG. 2 is moved to an initial position. It is a graph which shows the speed of the optical pick-up by the drive motor shown in FIG. It is a flowchart which shows the control method of a drive motor. It is the schematic of the conventional optical disk apparatus.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of an optical disc apparatus according to the present invention. As shown in FIG. 1, an optical disc apparatus A includes a traverse chassis 1, a turntable 2 attached to the traverse chassis 1 for rotating the optical disc, and an optical pickup 3 for irradiating the optical disc rotated by the turntable 2 with laser light. And.

  The traverse chassis 1 is formed by cutting and bending a metal plate into a rectangular shape. The traverse chassis 1 is held at four corners by a main chassis (not shown) via a damper member 11. The damper member 11 is a member that alleviates transmission of vibrations and shocks from the main chassis to the traverse chassis 1 or vice versa, and is formed of an elastically deformable material. The traverse chassis 1 has a rectangular opening 10 in the center. In addition, although the traverse chassis 1 has illustrated what was formed by cutting and bending a metal plate, it is not limited to it and may be a resin molded body.

  A turntable 2 is attached to the traverse chassis 1 near the center of one short side of the opening 10. The turntable 2 is fixed to the tip of the output shaft of a motor (not shown). As the motor rotates, the turntable 2 rotates. The turntable 2 includes a placement portion 21 for placing an optical disc, and a convex portion 22 that passes through an opening formed in the center of the optical disc. The turntable 2 is configured to sandwich the optical disk with a clamper (not shown).

  In the traverse chassis 1, two guide shafts 4, which are a main shaft 41 for guiding the optical pickup 3 and a sub shaft 42, are arranged in parallel. Both ends of the main shaft 41 and the sub shaft 42 are supported by a shaft support portion 6 provided in the traverse chassis 1. The guide shaft 4 (41, 42) is arranged so as to cross the opening 10 in the longitudinal direction.

  As shown in FIG. 1, the optical pickup 3 holds a pickup base 31, a laser optical system including an objective lens 32 disposed to face the information recording surface of the optical disc, and the objective lens 32, and provides a track direction and a focus direction. And an objective lens holder 33 that moves to the center.

  The pickup base 31 has a bearing portion 311 that fits on one guide shaft 4 (main shaft 41) and an engagement portion 312 that engages the other guide shaft 4 (sub shaft 42). The bearing portion 311 is fitted in the main shaft 41 with little play, and the engagement portion 312 is partially open and is engaged with the other guide shaft 42 with much play.

  The optical pickup 3 is slid so as to approach and separate from the turntable 2 by a drive mechanism provided in the traverse chassis 1. As shown in FIG. 1, the drive mechanism includes a lead screw 51 rotatably supported on the opposite side of the sub shaft 42 across the main shaft 41 of the traverse chassis 1, and a lead screw 51 fixed to the traverse chassis 1. And a drive motor 52 for rotationally driving the motor.

  The lead screw 51 has a right-handed spiral groove 510 formed on the outer peripheral surface thereof, and is supported by the traverse chassis 1 so as to be parallel to the guide shaft 4 (41, 42). The drive motor 52 is a stepping motor. The drive motor 52 is connected to the control device 8 and is driven when a drive pulse signal is input from the control device 8. The control device 8 includes a control circuit that controls the optical disk device in an integrated manner, and includes a control device such as a CPU or MPU. In FIG. 1, the control device 8 is connected only to the drive motor 52, but is not limited thereto, and is also connected to a motor that drives the optical pickup 3 and the turntable 2, so that the optical disk device A is connected. It is also possible to use a control device that performs integrated control. Further, the position of the control device 8 is not limited to the place shown in FIG. 1. For example, the control device 8 may be arranged in the main chassis and connected to the drive motor 52 with a cable. Details of the drive pulse signal input from the control device 8 to the drive motor 52 will be described later.

  The optical pickup 3 includes a driving force transmission unit to which the driving force from the lead screw 51 is transmitted. Details of the driving force transmission unit provided in the optical pickup 3 will be described with reference to the drawings. 2 is an enlarged plan view of the driving force transmission unit of the optical disc apparatus shown in FIG. 1, and FIG. 3 is an enlarged view of the driving force transmission unit of the optical disc apparatus shown in FIG.

  As shown in FIG. 2, the driving force transmission portion includes a convex portion 71 projecting from the pickup base 1 in a direction orthogonal to the guide shaft 4 (41), a rack portion 72 to which the driving force is transmitted from the lead screw 51, A leaf spring portion 73 that integrally connects the convex portion 71 and the rack portion 72 is provided.

  The convex portion 71, the rack portion 72, and the leaf spring portion 73 are an integrally molded body of resin, and the convex portion 71 is fixed to the pickup base 31 using a fastening tool such as a screw. Note that the pickup base 31 and the driving force transmission portion (entirely or at least the convex portion 71) may be integrally formed.

  The leaf spring portion 73 connects portions of the convex portion 71 and the rack portion 72 close to the traverse chassis 1. The convex portion 71 and the rack portion 72 have shapes that are difficult to deform, and the rack portion 72 moves in a direction approaching and separating from the lead screw 51 due to the elastic deformation of the leaf spring portion 73 substantially. Further, the leaf spring portion 73 connects the convex portion 71 and the rack portion 72 at two positions with a gap in the axial direction of the lead screw 51.

  Although the leaf spring portion 73 itself is a member having a spring property, a coil spring 74 is disposed between the convex portion 71 and the rack portion 72 in order to strongly press the rack portion 72 against the lead screw 51. The coil spring 74 is compressed and attached. In addition, the coil spring 74 does not need to be provided when the rack part 72 can be strongly pressed by the leaf spring part 73 so as not to drop off the lead screw 51.

  Since the leaf spring portion 73 is formed with a surface parallel to the axis of the lead screw 51, the leaf spring portion 73 has high rigidity in the feeding direction of the optical pickup 3, that is, the axial direction of the lead screw 51. Thus, when the lead screw 51 is rotated and the driving force is transmitted to the rack portion 72, the shaft of the lead screw 51 is between the convex portion 71 and the rack portion 72, that is, between the optical pickup 3 and the rack portion 72. It is possible to move the optical pickup 3 with high accuracy without causing a positional deviation in the direction.

  Since the rack portion 72 is connected to and supported by the convex portion 71 by the leaf spring portion 73, the rack portion 72 is bent about the leaf spring portion 73 and the lead screw 51 by bending the leaf spring portion 73. Swings between.

  The rack portion 72 will be described in detail. As shown in FIGS. 2 and 3, the rack portion 72 includes a base 720 connected to the leaf spring portion 73, and a claw portion that is a protrusion that is integrally formed with the base 720 and meshes with the spiral groove 510 of the lead screw 51. 721. Note that the right side in FIG. 2 and the left side in FIG. 3 are the turntable side, that is, the center side of the optical disc. As shown in the figure

  As shown in FIG. 3, the rack portion 72 is arranged side by side so that two claw portions 721 inclined in the clockwise direction in the drawing are parallel to each other. The direction of this inclination is determined by the turning direction of the spiral groove 510 of the lead screw 51 (in this embodiment, the right-hand screw direction), and the angle is determined by the pitch of the spiral groove 510. The claw portions 721 are arranged at intervals corresponding to the pitch of the spiral grooves 510 so that the claws 721 can mesh with the spiral grooves 510 of the lead screw 51. Further, the claw portion 721 has a shape that becomes narrower as it is away from the base 720 so that the side portion can come into contact with the valley portion of the spiral groove 510. When the lead screw 51 rotates, the claw portion 721 is pushed by the spiral groove 510, so that the optical pickup 3 follows the guide shaft 4 (41, 42) via the rack portion 72, the leaf spring portion 73, and the convex portion 71. Pushed in the direction.

  Next, a method for detecting the initial position of the optical pickup 3 will be specifically described. FIG. 4 is an enlarged view when the optical pickup used in the optical disk apparatus shown in FIG. 2 is moved to the initial position. As shown in FIG. 4, in the optical disc apparatus A, the initial position of the optical pickup 3 is set at the end opposite to the turntable 2. This is due to the shape of the spiral groove 510 of the lead screw 51 and the position of the leaf spring portion 73 of the driving force transmission portion. That is, when the lead screw 51 rotates to move the optical pickup 3 to the side opposite to the turntable 2, the claw portion 721 is pushed by the spiral groove 510 toward the leaf spring portion 73, and the claw portion 721 is moved from the spiral groove 510. It is hard to skip teeth.

  Thus, by setting the initial position of the optical pickup 3 at the end opposite to the turntable 2, the drive motor 52 can easily be stepped out, and the initial position of the optical pickup 3 can be detected accurately and quickly. Is possible. Note that the end of the turntable 2 can be set to the initial position by changing the spiral direction of the spiral groove 510 of the lead screw 51 and the position of the leaf spring portion 73. However, since the initial position is far from the drive motor 52 and an error due to the twist of the lead screw 51 may occur, the initial position is preferably in the vicinity of the drive motor 52.

  As shown in FIG. 2, the traverse chassis 1 is provided with a stopper 12 that is a restricting means that contacts the optical pickup 3 when the optical pickup 3 moves to the stroke end and regulates the movement of the optical pickup 3. Yes. The stopper 12 has a shape protruding into the opening 10 so as to be in contact with the vicinity of the bearing portion 311 of the pickup base 31. The stopper 12 is also used as a buffering member that reduces the impact when the optical pickup 3 collides with the traverse chassis 1.

  In the following description, the detection of the initial position immediately after the optical disk apparatus is turned on will be described as an example. However, in addition to this, the initial position may be detected when a new optical disk is inserted.

  By driving the drive motor 52 and rotating the lead screw 51, the claw portion 721 of the rack portion 72 is pushed into the spiral groove 510. As a result, the optical pickup 3 moves along the guide shaft 4 (41, 42) to the side opposite to the turntable 2.

  The optical pickup 3 moves to the stroke end opposite to the turntable 2 and comes into contact with the stopper 12. The optical pickup 3 stops and the driving force transmission unit also stops. At this time, a pulse signal for driving is input to the driving motor 52, and the driving is continued. As a result, torque is applied to the lead screw 51 in a direction in which the lead screw 51 continues to rotate, the claw portion 721 is biased in the rotational direction by the spiral groove 510, and the rack portion 72 has a direction to follow the rotation of the lead screw 51 and A force acts toward the outer peripheral side of the optical disk in the axial direction of the lead screw 51.

  Further, when the optical pickup 3 reaches the stroke end opposite to the turntable 2, the lead screw 51 is pressed by the rack portion 72 and the drive of the drive motor 52 is stopped. At this time, a drive pulse signal is input to the drive motor 52, and the drive motor 52 steps out. The control device 8 detects the step-out of the drive motor 52 to detect that the optical pickup 3 has moved to the initial position, and uses this position as the origin to determine the number of pulses of the pulse signal input to the drive motor 52. 3 position is controlled.

  The speed control to the drive motor, which is the main part of the present invention, will be described with reference to the drawings. FIG. 5 is a graph showing the speed of the optical pickup by the drive motor shown in FIG. 1, and FIG. 6 is a flowchart showing a control method of the drive motor. In FIG. 5, the optical pickup 3 moves from left to right and moves to the right end of the stroke. Further, the control shown in FIG. 6 shows the control for detecting the initial position of the optical pickup 3 immediately after the optical disc apparatus is powered on.

  First, general characteristics of the drive motor 52 will be described. The drive motor 52 is a constant voltage control stepping motor. The constant voltage control stepping motor has an output characteristic in which the torque decreases when a predetermined rotational speed is exceeded. That is, when the rotation speed is lower than the predetermined rotation speed and the rotation speed is low, the torque is large, and when the rotation speed is high, the torque is small. The rotation speed of the drive motor 52 is proportional to the frequency of the input pulse signal. That is, the drive motor 52 has a low rotational speed and a large torque when the pulse signal frequency is low, and a high rotational speed and a small torque when the pulse signal frequency is high.

  The detection of the initial position of the optical pickup 3 in the optical disk apparatus of the present invention utilizes the torque characteristics of this stepping motor. Hereinafter, detection of the initial position of the optical pickup when the optical disk apparatus of the present invention is turned on will be described.

  When the optical disk device is powered on (step S11), the control device 8 sends a signal to the drive motor 52 to place the drive motor 52 in the excitation hold state (step S12). The control device 8 inputs a start pulse signal for starting the drive motor 52 in the normal direction to the drive motor 52 (step S13). At this time, the start pulse signal is a pulse signal having a frequency at which the start pulse signal input to the drive motor 52 outputs torque and rotation speed that the drive motor 52 can send to the rack unit 72 in its own start region.

  When the drive motor 52 is activated and the optical pickup 3 starts to move, the control device 8 inputs a drive pulse signal to the drive motor 52 (step S14). The drive pulse signal is a pulse signal having a frequency with which the drive motor 52 can synchronize. That is, the pulse signal has a frequency that allows the drive motor 52 to rotate stably.

  Next, it adjusts so that the output torque of the drive motor 52 may become below predetermined torque. The predetermined torque is smaller than a moment (hereinafter referred to as a step-out torque) due to a force acting on the lead screw 51 from the rack portion 72 when the optical pickup 3 comes into contact with the stopper 12 and the rack portion 72 stops. Torque.

  As described above, the torque of the drive motor 52 is related to the frequency of the drive pulse signal, and the output torque of the drive motor 52 is reduced by increasing the frequency. Based on this characteristic, the control device 8 increases the frequency Fr1 of the drive pulse signal by a predetermined amount α (step S15). The frequency increase amount α is such that the drive motor 52 is not out of synchronization.

  The control device 8 has in advance a frequency Fr0 of the drive pulse signal at which the output torque of the drive motor 52 becomes a torque equal to or less than the step-out torque, and the frequency Fr0 of the drive pulse signal can be stepped out. Or less (step S16). When the frequency Fr1 of the drive pulse signal is smaller than the frequency Fr0 that can be stepped out (in the case of YES in step S16), the torque output from the drive motor 52 is larger than the stepout torque, and the process returns to step S15 to return the drive pulse signal. Increase the frequency Fr1 (region a in FIG. 5).

  When the frequency Fr1 of the drive pulse signal is larger than the frequency Fr0 that can be stepped out (NO in step S16), the control device 8 stores the frequency Fr2 at this time, and uses the drive pulse signal of the frequency Fr2 as the drive motor 52. (Step S17). With the drive torque smaller than the step-out torque, the drive motor 52 continues to drive, and the optical pickup 3 moves toward the opposite side of the turntable 2 at a constant speed (b region in FIG. 5). Contact. At this time, the movement of the rack portion 72 is stopped, and a force is applied to the lead screw 51 in a direction to stop the rotation from the rack portion 72. At this time, a step-out torque is acting on the drive motor 52 connected to the lead screw 51. Since the step-out torque is larger than the drive torque, the drive motor 52 cannot rotate and step out.

  When the control device 8 detects that the drive motor 52 has stepped out (step S18), the control device 8 recognizes that the optical pickup 3 has moved to the initial position, and applies the drive motor 52 recorded in the information recording unit such as a memory. The number of pulses of the input pulse signal is reset (step S19). A counter may be provided as counting means for counting the number of pulses of the pulse signal.

  By following the above procedure, when the optical pickup 3 moves to the stroke end and detects the initial position, the drive motor 52 steps out without the rack portion 72 skipping. Therefore, the initial position of the optical pickup 3 is determined. It is possible to detect stably and quickly.

  As described above, when the initial position of the optical pickup 3 is detected, it contacts the stopper 12 without decelerating, so that the impact acting on the optical pickup 3 or the stopper 12 is large. Therefore, it is preferable to adjust the frequency of the drive pulse signal when the optical pickup 3 is moved at a constant speed so that the output torque of the drive motor 52 is slightly smaller than the step-out torque. Thus, by adjusting the frequency of the drive pulse signal, when the optical pickup 3 comes into contact with the stopper 12, the drive motor 52 can be surely stepped out and an increase in the rotational speed of the drive motor 52 is suppressed. The moving speed of the optical pickup 3 can also be suppressed. Thereby, the impact when the optical pickup 3 contacts the stopper 12 can be suppressed.

  Furthermore, in order to suppress an impact when the optical pickup 3 comes into contact with the stopper 12, a buffer member may be provided in a portion in contact with the stopper 12 of the optical pickup 3. By the buffer member 34, the impact received when the optical pickup 3 comes into contact with the stopper 12 can be mitigated, and damage to the optical system mounted on the optical pickup 3 can be suppressed.

  In the above-described embodiment, the initial position of the optical pickup 3 is the end on the side opposite to the turntable 2, but it may be the end on the turntable 2. In the optical disk device of the above embodiment, constant voltage control is performed as control of the drive motor 52, but the present invention is not limited to this.

  The present invention can be used for an optical disc apparatus that detects an initial position of an optical pickup at the time of power-on or the like by detecting the stepping motor step-out by causing the optical pickup to reach the stroke end.

DESCRIPTION OF SYMBOLS 1 Traverse chassis 11 Damper member 12 Stopper 2 Turntable 3 Optical pickup 31 Pickup base 32 Objective lens 33 Objective lens holder 4 Guide shaft 51 Lead screw 52 Drive motor 6 Shaft instruction | indication part 71 Convex part 72 Rack part 73 Leaf spring part 74 Coil spring

Claims (3)

An optical pickup supported so as to be slidable in the radial direction of the optical disc;
A lead screw arranged so that its axis is parallel to the sliding direction of the optical pickup;
A drive motor that is a stepping motor that rotationally drives the lead screw and is controlled at a constant voltage;
A driving force transmission unit coupled to the optical pickup via an elastic member and meshing with the lead screw;
A restricting means that is disposed near the stroke end of the optical pickup and prevents the optical pickup from sliding,
An optical disc device comprising a control means for sending and driving a pulse signal to the drive motor,
When the control means detects the initial position of the optical pickup, the frequency of the pulse signal is increased by an amount that does not cause the synchronization of the drive motor, and the output torque of the drive motor is determined by the drive force transmission unit. optical disc apparatus characterized by to increase until it exceeds the smaller becomes frequency than the moment acting on the lead screw by the force for pressing the lead screw.   The control means, after exciting and holding the drive motor, sends a start pulse signal that can be activated automatically to the drive motor, the drive motor is driven, and the optical pickup starts moving, and then the drive motor is driven to the drive motor. Sending a pulse signal, adjusting the frequency of the drive pulse signal so that the output torque of the drive motor is smaller than the moment acting on the lead screw by the force with which the driving force transmission part presses the lead screw, and 2. The optical disc apparatus according to claim 1, wherein a drive pulse signal having the adjusted frequency is sent to the drive motor. A counting means for counting the number of pulses of the pulse signal sent from the control means to the drive motor;
The optical disk apparatus according to claim 1, wherein the control unit resets the counting unit when the detection of the initial position of the optical pickup is completed.

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