JP2008251104A - Optical pickup device and its control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device and its control device in which switching of an ND filter caused by disturbance can be detected automatically during operation and during inspection in a manufacturing line. <P>SOLUTION: An optical pickup device comprises an optical pickup 100 which is provided with an LD1 emitting light irradiating an optical disk, an ND filter 2 adjusting light quantity of out-going light from the LD1, a FPD 4 receiving light adjusted by this ND filter 2 and outputting a detected signal, and an APC5 in which it is judged based on this detected signal whether a drive current of the LD1 is appropriate or not and which sends out a control signal to the LD1 so as to become appropriate, and a control part 101 provided with a CPU 8 monitoring the control signal from the APC5 and drive-controlling the ND filter 2 based on the control signal when the drive current exceeds the prescribed threshold value for the prescribed time and changes. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical pickup device applicable to, for example, an optical disk drive device and a control device thereof, and more particularly to an optical pickup device using an ND filter and a control device thereof.

  Conventionally, for example, an ND (Neutral Density) filter is used in a laser beam path of an optical pickup device. This ND filter may be switched unintentionally due to an external impact due to its structure. In such a case, an operation failure of the optical pickup device or erroneous data writing to the disk may be caused. .

  Conventionally, with respect to such a problem, an acceleration sensor is provided outside the optical pickup device, and when an output (acceleration signal) exceeding a predetermined threshold is detected, the operation is interrupted and the ND filter is mechanically operated again. A method of redrawing is used.

  Further, at the time of inspection on the production line, conventionally, a method has been adopted in which an operator individually confirms the operation based on the operation sound of the ND filter disposed in the optical pickup device.

  Note that, for the purpose of optical adjustment of the optical pickup device, for example, in Patent Document 1, a detection means for detecting a drive current supplied to a light source is provided, and a movable mirror is provided based on a change in the drive current. An optical pickup adjusting device for adjusting an outgoing optical axis by rotating is disclosed.

JP 2000-331349 A

  However, when the above-described acceleration sensor output exceeds a predetermined threshold, the operation is interrupted and the ND filter is mechanically pulled back, so that the output of the acceleration sensor does not exceed the predetermined threshold, It is not possible to cope with a changeover without intention.

  Further, in the above-described method of checking the production line, the method of checking and confirming the operation sound when checking the operation of the ND filter requires a wasteful check man-hour for the production line.

  Accordingly, an object of the present invention is to automatically detect switching due to disturbance of the ND filter at least during operation of the optical pickup device and during inspection on the production line.

  In the optical pickup device according to the first aspect of the present invention, the light emitting means emits light that irradiates the optical disc, the light quantity adjusting means adjusts the light quantity of the emitted light from the light emitting means, and the light receiving means is the light quantity adjusting means. The light adjusted in accordance with the above is received, a detection signal is output, and the drive current control means determines whether or not the drive current of the light emitting means is appropriate based on the detection signal, and the light emission so as to be appropriate. A control signal is sent to the means. In particular, the control means monitors the control signal from the drive current control means, and when the drive current changes beyond a predetermined threshold during a predetermined time based on the control signal, the light amount adjustment means is Drive control.

  Therefore, the control means automatically detects an abnormal state of the light quantity adjusting means based on the drive current of the light emitting means, and the light quantity adjusting means is redrawn to an appropriate position.

  The control device of the optical pickup device according to the second aspect of the present invention comprises: a light emitting unit that emits light that irradiates an optical disc; a light amount adjusting unit that adjusts the amount of light emitted from the light emitting unit; and the light amount adjusting unit. A light receiving unit that receives the adjusted light and outputs a detection signal, and determines whether or not the drive current of the light emitting unit is appropriate based on the detection signal, and controls the light emitting unit to be appropriate. A control device for an optical pickup device comprising a drive current control means for transmitting a signal, wherein the control means monitors a control signal from the drive current control means, and the drive current is determined based on the control signal. When the time changes exceeding a predetermined threshold during the time, the light amount adjusting means is driven and controlled.

  Therefore, the control unit automatically detects an abnormal state of the light amount adjusting unit based on the drive current of the light emitting unit, and controls the light amount adjusting unit to be pulled back to an appropriate position.

  ADVANTAGE OF THE INVENTION According to this invention, the optical pick-up apparatus which can detect automatically the switch by the disturbance of ND filter at the time of an operation | movement and the test | inspection in a production line, and its control apparatus can be provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a best mode for carrying out the invention (hereinafter simply referred to as an embodiment) will be described in detail with reference to the drawings.

  FIG. 1 shows and describes the configuration of an optical pickup device and its control device according to an embodiment of the present invention. This optical pickup device includes an optical pickup 100 and its control unit 101. The control unit 101 functions as the control device.

  As shown in FIG. 1, on the optical pickup 100 side, an ND filter 2 that can move in a plane perpendicular to the optical axis is disposed on the optical path of the emitted light of a laser diode (LD) 1. Has been. The LD 1 functions as, for example, a light emitting unit, and the ND filter functions as a part of the light amount adjusting unit, for example. Further, a prism beam splitter (PBS) 3 is disposed on the optical axis ahead.

  The PBS 3 separates the incident light into two orthogonal polarization components and emits them.

  The PBS 3 irradiates part of the light to the optical disk 11 and part of the light is guided to a front photo detector (FPD) 4.

  The FPD 4 functions as, for example, a light receiving unit. The output of the FPD 4 is connected to an input of an automatic power control (APC) 5, and the output of the APC 5 is connected to the LD 1 and the A / D converter 7 on the control unit 101 side. The APC 5 functions as drive current control means, for example.

  On the other hand, on the control unit 101 side, the output of the A / D converter 7 is connected to the input of a central processing unit (CPU) 8, and the CPU 8 is connected via a control bus 12 to a RAM (random access). Memory) 10 and ROM (Read Only Memory) 9 are connected. The ROM 9 stores in advance a control program for driving and controlling the ND filter 2 and parameters such as a threshold value to be described later. The RAM 10 is used as a temporary storage area for various calculations, for example. The output of the CPU 8 is connected to the drive unit 6 for driving the ND filter 2 on the optical pickup 100 side. Although this drive part 6 is comprised by the plunger etc., for example, it is not limited to this. The drive unit 6 functions as a part of the light amount adjusting unit, for example.

  In such a configuration, the light emitted from the LD 1 is irradiated onto the optical disc 11 through the ND filter 2 and the PBS 3. The ND filter 2 plays a role of reducing the intensity of light emitted from the LD 1 by a predesigned ratio. That is, the amount of outgoing light is adjusted by the ND filter 2. Part of the emitted light is reflected by the PBS 3 and detected by the FPD 4. The FPD 4 sends the detection signal of the LD 1 to the APC 5. The APC 5 detects the drive current of the LD 1 based on the detection signal. If the drive current is not appropriate, the APC 5 sends a control signal to the LD 1 to control the drive current to be appropriate.

  The control signal of the APC 5 is also sent as a monitor signal to the A / D converter 7 on the control unit 101 side, converted into a digital signal by the A / D converter 7, and sent to the CPU 8. The CPU 8 monitors the drive current of the LD 1 based on this digital signal, and when the drive current changes suddenly, the CPU 8 determines that the ND filter 2 has been switched unintentionally due to an impact or the like, and interrupts the operation. Then, the driving unit 6 is driven to start the operation of drawing the ND filter 2 in the correct direction. In this control, the CPU 8 reads a control program stored in the ROM 9 and executes control based on the control program. At that time, various parameters such as a threshold value stored in the ROM 9 are referred to.

  When the ND filter 2 that controls the light amount of the LD 1 is switched unintentionally, feedback control is activated in the loop from the APC 5 to the LD 1, and the APC 5 operates in a direction to adjust the drive current. Therefore, if this change in the drive current is constantly observed, it can be determined whether or not an unintended switching of the ND filter 2 has occurred due to an impact.

  Hereinafter, with reference to the flowchart of FIG. 2, the process by the optical pickup device according to the embodiment of the present invention, particularly the control device (corresponding to the control unit 101) will be described in detail.

  This process is performed in parallel with the drive current control of the LD 1 by the APC 5.

  The CPU 8 monitors the drive current of the LD 1 converted into a digital signal by the A / D converter 7 (step S1), and determines whether or not the amount of change in the drive current of the LD 1 exceeds a predetermined threshold value. (Step S2). For example, in FIG. 3, the horizontal axis indicates time, and the vertical axis indicates the drive current of LD1, but when the drive current changes rapidly in a short time and the amount of change exceeds a predetermined threshold, The CPU 8 detects that an abnormality has occurred.

  If the drive current does not exceed the threshold value in step S2 (step S2 branches to No), the process returns to step S1 to continue monitoring the drive current. On the other hand, when the drive current exceeds the threshold (step S2 branches to Yes), the CPU 8 determines that the ND filter 2 has been switched unintentionally due to an impact such as dropping (step S3). The drive operation of the pickup 100 is interrupted, a control signal is sent to the drive unit 6, the ND filter 2 is redrawn by the drive unit 6 (step S4), and this process ends.

  Although the above is the embodiment as the optical pickup device and its control device, the above-described processing can also be adopted for the operation check on the production line. In this case, when the LD is caused to emit light and only the ND filter is switched, it is observed whether or not the LD drive current has changed. If the current changes before and after, it can be determined that the operation is normal.

  As described above, according to the optical pickup device and the control device thereof according to an embodiment of the present invention, it is possible to detect a switching due to an ND filter abnormality, for example, a disturbance, and to automatically correct the state. In addition, it is possible to automatically check whether or not the ND filter has a failure. Furthermore, the operation can be automatically confirmed on the production line.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and it is needless to say that various improvements and changes can be made without departing from the spirit of the present invention.

  For example, a threshold value of a change amount related to a drive current change for detecting an abnormality of the ND filter may be determined for each mode of the dual layer (DL) and the single layer (SL).

It is a block diagram which shows the structure of the optical pick-up apparatus which concerns on one embodiment of this invention, and its control apparatus. 4 is a flowchart for explaining in detail processing performed by the optical pickup device according to an embodiment of the present invention, particularly a control device (corresponding to the control unit 101). It is a characteristic view which shows the change of the drive current with progress of time.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... LD, 2 ... ND filter, 3 ... PBS, 4 ... FPD, 5 ... APC, 6 ... Drive part, 7 ... A / D converter, 8 ... CPU, 9 ... ROM, 10 ... RAM, 11 ... Optical disk, 100 ... Optical pickup, 101 ... Control unit

Claims (4)

A light emitting means for emitting light for irradiating the optical disc;
A light amount adjusting means for adjusting the amount of light emitted from the light emitting means;
A light receiving means for receiving the light adjusted by the light amount adjusting means and outputting a detection signal;
A drive current control means for judging whether or not the drive current of the light emitting means is appropriate based on the detection signal, and for sending a control signal to the light emitting means so as to be appropriate;
Control means for monitoring a control signal from the drive current control means, and for controlling drive control of the light amount adjusting means when the drive current changes beyond a predetermined threshold during a predetermined time based on the control signal. An optical pickup device characterized by that. The light amount adjusting means comprises a neutral density filter and driving means,
The optical pickup apparatus according to claim 1, wherein the control means changes the position of the neutral density filter by sending a control signal to the driving means. A light emitting means for emitting light irradiating the optical disc, a light quantity adjusting means for adjusting the light quantity of the emitted light from the light emitting means, a light receiving means for receiving the light adjusted by the light quantity adjusting means and outputting a detection signal; An optical pickup device comprising: a drive current control means for judging whether or not the drive current of the light emitting means is appropriate based on the detection signal and sending a control signal to the light emission means so as to be appropriate; A control device,
Control means for monitoring a control signal from the drive current control means and controlling the drive of the light amount adjusting means when the drive current changes beyond a predetermined threshold during a predetermined time based on the control signal. A control device for an optical pickup device. The light amount adjusting means comprises a neutral density filter and driving means,
The control device for an optical pickup device according to claim 3, wherein the control means changes the position of the neutral density filter by sending a control signal to the driving means.

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