JP2007250033A - Optical disk drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk drive which can use various kinds of optical recording mediums and reduce the time needed to discriminate the kind of the disk. <P>SOLUTION: The optical disk drive, when discriminating the kind of an optical recording medium, alternately turns on at least two out of the light sources and moves the objective lens in the direction approaching the disk or moving apart from it each time to find the focusing error signals to be obtained by processing the signals from the photodetector. It decides the timing to turn on the light sources based on the detection of the S curve of the focusing error signals. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an optical disk device used for recording and reproducing information on an optical recording medium, and more particularly to a technique for shortening an optical recording medium discrimination time in the optical disk device.

  Optical recording media such as compact discs (hereinafter referred to as CDs) and digital versatile discs (hereinafter referred to as DVDs) are widely used. Recently, in order to further increase the amount of information in the optical recording medium, research on increasing the density of the optical recording medium has been advanced, and for example, a higher-density optical recording medium such as a Blu-ray disc (hereinafter referred to as BD). Has also been put to practical use. In addition, there are optical recording media having a plurality of recording layers in order to increase the recording capacity, for example, hybrid discs in which a CD recording layer and a DVD recording layer are mixedly mounted, and there are various types of optical recording media. It is diverse.

  Such recording and reproduction of information on an optical recording medium is performed in an optical disk apparatus, but an optical disk apparatus having a configuration capable of recording and reproducing a plurality of types of optical recording media with one optical disk apparatus has been actively developed. In general, in an optical disc apparatus corresponding to a plurality of types of optical recording media, when the optical recording medium is inserted into the apparatus, first, the type of the optical recording medium is determined. Therefore, the time required for discriminating the optical recording medium tends to be long.

  FIG. 5 shows an operation of discriminating the type of the optical recording medium by the conventional optical disc apparatus. Here, it is assumed that the optical disk device is an optical recording medium corresponding to the first to third optical recording media. When the optical recording medium is inserted into the optical disc apparatus, first, a laser diode for the first optical recording medium (hereinafter sometimes referred to as LD) emits light. When the laser output of the LD is stabilized by the action of APC (Auto Power Control), the LD moves to the direction closer to the optical recording medium with respect to the thickness direction of the optical recording medium, and the amplitude of the S-shaped waveform of the focus error signal Is measured. When the objective lens approaches a predetermined position with respect to the optical recording medium, the objective lens is then moved in a direction away from the optical recording medium with respect to the thickness direction of the optical recording medium, and again the amplitude of the S-shaped waveform. Is measured.

  When the objective lens is moved away from the optical recording medium to a predetermined position, the LD for the first optical recording medium is turned off and the LD for the second optical recording medium emits light. At the time of switching the LD, a certain amount of time is required until the laser output of the LD is stabilized, so a switching time is required. After the switching time has elapsed, the amplitude of the S-shaped waveform is measured in the same manner as after emitting the LD for the first optical recording medium, and similarly, the LD for the third optical recording medium is emitted, and S The amplitude of the letter waveform is measured. Based on the amplitude of the obtained S-shaped waveform, the type of the optical recording medium is determined.

  However, in the conventional method for discriminating an optical recording medium, since the amplitude measurement of the S-shaped waveform is performed twice for each LD, it takes more time to discriminate the type of the optical recording medium. There was a problem that required. In consideration of this point, Patent Document 1 is configured to switch the LD to emit light when the objective lens is moved closer to the optical recording medium and when the objective lens is moved away from the optical recording medium. According to this, since the amplitude measurement of the S-shaped waveform is performed only once for each LD, the time for determining the type of the optical recording medium is shortened.

In Patent Document 2, the range in which the objective lens is moved in order to obtain an S-shaped waveform is different for each LD having different target optical recording media, and the objective lens is not moved to an unnecessary position. By configuring, the time is shortened, and the time required for discriminating the type of the optical recording medium is shortened.
JP 2000-31357 A JP 2005-353201 A

  However, in the optical disk devices in Patent Document 1 and Patent Document 2, the time required for the output of the laser light emitted from the LD to become stable when the LD is switched is not taken into consideration. That is, in the optical disk apparatus having the configuration of Patent Document 1, for example, when the LD is switched and immediately starts moving the objective lens in the direction away from the optical recording medium, the laser output of the LD is not stable and the S-shaped waveform is obtained. There is a possibility of measuring the amplitude, and there is a possibility of discriminating the type of the optical recording medium.

  In the optical disk device having the configuration of Patent Document 2, since the moving time of the objective lens is shortened as much as possible, when the time until the laser output is stabilized after switching of the LD is not considered, S The risk of erroneously determining the optical recording medium is further increased due to inaccurate measurement of the amplitude of the character waveform. For this reason, also in the optical disk devices having the configurations of Patent Document 1 and Patent Document 2, it is necessary to consider the time required for switching the LD and stabilizing the laser output of the LD. There is a drawback that the time required for discriminating the type of the optical recording medium becomes long.

  In view of the above points, an object of the present invention is to provide an optical disc apparatus capable of reducing the time required for discriminating the type of optical recording medium in an optical disc apparatus of a plurality of types of optical recording media. Another object of the present invention is to provide an optical disc apparatus capable of shortening the time required for discriminating the type of recording medium and accurately discriminating the type of optical recording medium.

  To achieve the above object, the present invention provides a plurality of light sources that emit light beams of different wavelengths, an objective lens that focuses the light beams emitted from the light sources on a recording surface of an optical recording medium, and the optical recording A type of the optical recording medium inserted in the apparatus, comprising: a light detection unit that receives reflected light reflected by the medium; and an actuator that moves the objective lens in a focus direction parallel to an optical axis direction thereof. In the determination, at least two of the plurality of light sources are switched in order to emit light, and in each case, the actuator moves the objective lens closer to the optical recording medium or from the optical recording medium. In an optical disc apparatus that detects a focus error signal obtained by moving a signal away from the light detection unit and processing a signal from the light detection unit, the light source is turned off. Timing changing is characterized in that is determined based on the detection of the S-shaped waveform of the focus error signal.

  According to the present invention, in the optical disc apparatus configured as described above, the light emission of the light source is switched immediately after the entire S-shaped waveform or a predetermined part of the S-shaped waveform is detected.

  Further, in the optical disk apparatus having the above-described configuration, the present invention may be configured to switch the light emission of the light source after detecting the entire S-shaped waveform or a predetermined part of the S-shaped waveform. It is characterized in that it is performed before the movement of the objective lens for detecting the focus error signal in the direction approaching the optical recording medium or the direction moving away from the optical recording medium is completed.

  According to the present invention, in the optical disc apparatus having the above-described configuration, the optical disc apparatus includes a detection unit that detects a light output of the light beam emitted from the light source, and the actuator for detecting the focus error signal in each light source. The movement of the objective lens is started after the light output is stabilized.

  Further, the present invention is characterized in that the number of light sources to be switched is three or more in the optical disc apparatus having the above-described configuration.

  Further, the present invention is the optical disc apparatus having the above-described configuration, wherein the light source includes a one-wavelength light source that emits only a light beam having a single wavelength and a two-wavelength light source that emits a light beam having two wavelengths, The order in which the light sources emit light is the order of a light source that emits one wavelength of the two-wavelength light source, the one-wavelength light source, and a light source that emits the other wavelength of the two-wavelength light source. .

  According to the first configuration of the present invention, it is possible to efficiently ensure the time for stabilizing the light output (laser power) required for the switched light source. For this reason, the movement of the objective lens for detecting the S-shaped waveform performed with respect to the switched light source can shorten the waiting time that occurs until the movement starts, and is required to determine the type of the optical recording medium. Time can be reduced.

  Further, according to the second configuration of the present invention, it is possible to most efficiently secure the time for stabilizing the light output for the switched light source in the optical disc apparatus having the first configuration.

  According to the third configuration of the present invention, in the optical disk device having the first configuration, the light source is switched during the movement of the objective lens required for detecting the S-shaped waveform of the focus error signal. Therefore, it is possible to efficiently secure a time for stabilizing the light output of the switched light source.

  According to the fourth configuration of the present invention, in the optical disc apparatus having any one of the first to third configurations, the time required for discriminating the optical recording medium is shortened and the optical recording medium is accurately set. Accordingly, it is possible to provide an optical disc apparatus having a simple configuration capable of determining the above.

  Further, according to the fifth configuration of the present invention, in the optical disc apparatus having any one of the first to fourth configurations, the effect of shortening the time required for discriminating the optical recording medium can be further increased.

  Further, according to the sixth configuration of the present invention, in the optical disc apparatus having any one of the first to fifth configurations, when a two-wavelength light source is used in order to have advantages in the size and manufacturing cost of the optical disc apparatus. Thus, it is possible to efficiently secure the switching time required when switching the light source.

  The content of the present invention will be described in detail below, but the embodiment shown here is an example, and the present invention is not limited to the embodiment shown here.

  FIG. 1 is a block diagram showing the configuration of the optical disc apparatus of the present embodiment. The optical disc apparatus 1 can reproduce information from the optical recording medium 15 and record information on the optical recording medium 15. Reference numeral 2 denotes a spindle motor, and the optical recording medium 15 is detachably held by a chuck portion (not shown) provided on the top of the spindle motor 2. When recording / reproducing information on the optical recording medium 15, the spindle motor 2 continuously rotates the optical recording medium 15. The rotation control of the spindle motor 2 is performed by the spindle motor control unit 3.

  An optical pickup 4 irradiates the optical recording medium 15 with laser light emitted from a light source, and can write information on the optical recording medium 15 and read information recorded on the optical recording medium 15. To do. FIG. 2 is a schematic diagram showing an optical system of the optical pickup 4. As shown in FIG. 2, the optical pickup 4 includes light sources 16 and 17, a color synthesis prism 18, a collimator lens 19, a beam splitter 20, an objective lens 21, a condenser lens 23, and a photodetector 24. . The configuration of the optical system that constitutes the optical pickup is not limited to this, and various changes can be made.

  The light sources 16 and 17 are both laser diodes (LDs), but the light source 16 is a two-wavelength light source that can emit laser light of two types of wavelengths, and the light source 17 emits only laser light of a single wavelength. It is a one-wavelength light source. The two-wavelength light source 16 emits laser light having a wavelength corresponding to DVD and CD (for example, laser light having a wavelength of 650 nm and 780 nm), and the one-wavelength light source 17 emits laser light corresponding to BD (for example, Laser beam having a wavelength of 405 nm is emitted.

  In the optical pickup 4, the light beams emitted from the light sources 16 and 17 have the same optical axis by the color synthesis prism 18, become parallel light by the collimator lens 19, pass through the beam splitter 20, and are optically recorded by the objective lens 21. The information on the medium 15 is collected on the recording surface 15a on which the information is recorded. The reflected light reflected by the optical recording medium 15 passes through the objective lens 21, is reflected by the beam splitter 20, and is collected by a condenser lens 23 onto a light receiving unit (not shown) of the photodetector 24. The photodetector 24 converts optical information contained in the received light beam into an electrical signal.

  Returning to FIG. 1, the optical disc apparatus 1 is provided with a laser control unit 5, so that the light output of the light beams emitted from the light sources 16 and 17 is made constant at a predetermined value by the laser control unit 5. To be controlled. For the control of making the optical output constant, a laser power is detected as a voltage signal by a light receiving element (light receiving element for front monitor) (not shown), and an LD (light source 16,. This is done by supplying power to 17).

  The signal processing unit 7 includes at least an RF signal processing unit 8, a track error signal processing unit 9, and a focus error signal processing unit 10. Then, an RF signal, a track error signal (TE signal), and a focus error signal (FE signal) are generated based on the electrical signal converted by the photodetector 24 (see FIG. 2). The RF signal is demodulated into data by the data demodulator 11 and output to an external device such as a personal computer via the interface 12. The TE signal and the FE signal are output to the actuator control unit 6.

  The actuator controller 6 supplies a drive signal to the actuator 22 (see FIG. 2) on which the objective lens 21 is mounted based on the signal sent from the signal processor 7. The actuator 22 to which the drive signal is supplied operates each part based on the signal and moves the objective lens 21 in a focus direction parallel to the optical axis direction to perform focusing control, and the objective lens 21 is optically recorded. Tracking control is performed to move the spot position of the laser beam to the track position formed on the optical recording medium 15 by moving in a direction parallel to the radial direction of the medium 15.

  The actuator control unit 6 also controls the movement of the objective lens 21 when determining the type of the optical recording medium 15 inserted into the optical disc apparatus 1 or when performing a focus pull-in operation.

  In addition, the overall control unit 13 includes a spindle motor control unit 3, a laser control unit 5, an actuator control unit 6, a signal processing unit 7, a data demodulation unit 11, an interface 12, and a storage unit 14 that stores information necessary for control. To control the entire device.

  In such an optical disc apparatus 1, for example, when the optical recording medium 15 is inserted into the apparatus or when the apparatus is started, the optical disc apparatus 1 determines the type of the optical recording medium 15 inserted in the apparatus, Based on the result of the determination, setting suitable for the optical recording medium 15 inserted in the apparatus is performed. The optical disc apparatus 1 according to the present embodiment is configured to reduce the time required for discriminating the optical recording medium 15. Hereinafter, this point will be described.

  FIG. 3 is a flowchart showing an operation in the case where the type of the optical recording medium 15 is determined in the optical disc apparatus 1 of the present embodiment. FIG. 4 is a schematic diagram for explaining the operation of discriminating the type of optical recording medium. The operation when the optical disk apparatus 1 determines the optical recording medium 15 will be described below with reference to the flowchart shown in FIG. 3 and the schematic diagram of FIG.

  When the overall control unit 13 instructs the optical recording medium 15 to be discriminated, first, the actuator control unit 6 drives the actuator 22 so that the objective lens 21 moves to a predetermined start position (step S1). ). When the objective lens 21 is moved to the start position, the laser controller 5 emits (ON) the DVD laser of the two-wavelength light source 16 (step S2).

  The laser power (optical output) of the laser light emitted from the DVD laser is controlled to be constant by the laser control unit 5, but it takes time until the laser power is stabilized. Therefore, it is confirmed whether or not the laser power is stabilized (step S3). If the laser power is not stable, this confirmation is repeated until the laser power is stabilized. Whether the laser power is stabilized may be confirmed by a known method. For example, the difference between the voltage value obtained by the light receiving element for the front monitor and the target voltage value is detected, and this difference is determined by a predetermined value. It can be realized by a method such as confirming whether it is within the range.

  In the present embodiment, the laser power stability confirmation is performed. However, the present invention is not limited to this, and a configuration in which the laser power stability confirmation is not performed may be used. However, for example, if the focus error signal is measured in a state where the laser power is not stable, and the type of the optical recording medium is determined based on the measurement result, the type of the optical recording medium 15 may be erroneously determined. Therefore, it is preferable to check the stability of the laser power.

  When the laser power is stable, a focus drive signal (see FIG. 4) for instructing the actuator 22 to drive in the focus direction is output from the actuator controller 6 and the objective lens 21 approaches the optical recording medium (this embodiment). In the embodiment, the movement starts in the direction in which the objective lens 21 rises (step S4). At the same time, measurement of the signal level of the focus error signal is started (step S5). The measured focus error signal is stored in the storage unit 14 (step S6).

  Next, it is confirmed whether or not the entire S-shaped waveform of the focus error signal has been detected (step S7). Note that the S-shaped waveform indicates a signal waveform (see FIG. 4) generated when the focus position of the objective lens passes the recording surface of the optical recording medium 15 in the focus error signal. Detailed description thereof is omitted. Also, the entire S-shaped waveform refers to the entire S-shaped waveform from A to O to B in FIG.

  As a method for determining whether or not the entire S-shaped waveform of the focus error signal has been detected, for example, there is a method of determining by taking each difference of the signal data of the focus error signal stored in the storage unit 14. That is, when the detection of the entire S-shaped waveform is completed, the change in the signal level of the focus error signal is almost eliminated, so that the difference in signal data becomes very small. Therefore, if it is determined whether or not the difference in the signal data is within a predetermined range, it is possible to determine whether or not the detection of the entire S-shaped waveform has already been completed.

  When the entire S-shaped waveform of the focus error signal has not been detected, measurement of the signal level of the focus error signal and storage thereof (steps S5 and S6) are continued. On the other hand, when the entire S-shaped waveform of the focus error signal is detected, the DVD laser is turned off (OFF) (step S8), and the BD laser of the one-wavelength light source 17 is emitted (step S9). If the entire S-shaped waveform can be confirmed, it is preferable to turn off the DVD laser and emit light from the BD laser in as short a time as possible.

  After the BD laser is emitted, it is confirmed whether or not the objective lens 21 has been raised to a predetermined position (step S10). Note that since the timing at which the S-shaped waveform appears varies depending on the type of the optical recording medium 15, the predetermined position of the objective lens 21 includes all the optical recording media 15 that can be handled by the optical disc apparatus 1 together with the start position of the objective lens 21. It is determined so as to secure a moving distance capable of detecting the S-shaped waveform. Further, in consideration of the displacement of the focal position due to the surface shake accompanying the rotation of the optical recording medium 15, the distance is set to be slightly longer than the moving distance capable of detecting each S-shaped waveform.

  If the objective lens 21 has not risen to the predetermined position, the confirmation in step S10 is repeated until the objective lens 21 reaches the predetermined position. On the other hand, when the objective lens 21 is raised to a predetermined position, the movement of the objective lens 21 by the actuator 22 is stopped at that position (step S11), and it is confirmed whether or not the laser power of the BD laser is stabilized (step S12). . The confirmation of the stability of the laser power is the same as in the case of the DVD laser.

  When the laser power of the BD laser is stabilized, a focus drive signal (see FIG. 4) for instructing the actuator 22 to drive in the focus direction is output from the actuator control unit 6 and the objective lens 21 moves away from the optical recording medium (this embodiment). Then, the movement starts in the direction in which the objective lens 21 descends (step S13). At the same time, measurement of the signal level of the focus error signal is started (step S14). The measured focus error signal is stored in the storage unit 14 (step S15).

  Next, it is confirmed whether or not the entire S-shaped waveform of the focus error signal has been detected (step S16). When the entire S-shaped waveform of the focus error signal has not been detected, measurement of the signal level of the focus error signal and storage thereof (steps S14 and S15) are continued. On the other hand, when the entire S-shaped waveform of the focus error signal is detected, the BD laser is turned off (step S17), and the CD laser of the two-wavelength light source 16 is emitted (step S18). If the entire S-shaped waveform can be confirmed, it is preferable to turn off the BD laser and emit the CD laser in as short a time as possible.

  After the CD laser is emitted, it is confirmed whether or not the objective lens 21 has been lowered to a predetermined position (step S19). The predetermined position here corresponds to the start position in step S1. When the objective lens 21 is not lowered to the predetermined position, the confirmation as to whether the objective lens 21 is lowered to the predetermined position is repeated until the objective lens 21 reaches the predetermined position.

  On the other hand, when the objective lens 21 is lowered to a predetermined position, the movement of the objective lens 21 by the actuator 22 is stopped at that position (step S20), and it is confirmed whether or not the laser power of the CD laser is stabilized (step S12). . The confirmation of the stability of the laser power is the same as in the case of the DVD laser.

  When the laser power of the CD laser is stabilized, the actuator 22 starts to raise the objective lens 21 (step S22), and at the same time, measurement of the signal level of the focus error signal is started (step S23). The measured focus error signal is stored in the storage unit 14 (step S24).

  Next, it is checked whether or not the entire S-shaped waveform of the focus error signal has been detected (step S25). If the entire S-shaped waveform of the focus error signal has not been detected, the focus error signal Signal level measurement and storage (steps S23 and S24) are subsequently performed.

  On the other hand, if the entire S-shaped waveform of the focus error signal has been detected, the CD laser is turned off (step S26). The movement of the objective lens 21 is also stopped after this, but the movement of the objective lens 21 may be stopped after the CD laser is turned off, and the movement is stopped after the objective lens 21 moves to a predetermined position. It does not matter as a structure to do.

  Thereafter, the measured value stored in the storage unit 14 is used to determine the amplitude of the S-shaped waveform (see FIG. 4) when each LD emits light, and the type of the optical recording medium 15 is determined from the level of the amplitude. A determination is made (step S27).

  Note that the method for discriminating the type of the optical recording medium 15 is not limited to the method using amplitude, and various modifications can be made without departing from the object of the present invention. That is, for example, not the amplitude but the time until the S-shaped waveform is observed when the objective lens 21 is moved in the focus direction is the distance from the disk surface of the optical recording medium 15 to the recording surface. A configuration in which the type of the optical recording medium 15 is discriminated using a point that differs depending on the type of the medium 15 may be used. Further, the optical recording medium 15 may be focused on the recording surface 15a using an S-shaped waveform, and the type of the optical recording medium 15 may be determined using a tracking error signal.

  The configuration for determining the type of the optical recording medium 15 as described above shortens the time required to determine the type of the optical recording medium 15 as compared to the conventional case. This point will be described with reference to FIG. explain.

  As described above, in the case of the present embodiment, the amplitude of the S-shaped waveform is measured and the type of the optical recording medium 15 is discriminated using this amplitude, so that at least the maximum signal level of the S-shaped waveform is obtained. It is necessary to detect the value and the minimum value. Considering this point, in the present embodiment, the entire S-shaped waveform of the focus error signal is detected for each light source that emits light.

  On the other hand, after the entire S-shaped waveform has been detected, the light sources 16 and 17 do not necessarily have to emit light even while the objective lens 21 is being raised by the actuator 22. Considering the time until the laser power of the light sources 16 and 17 to be emitted next is stabilized (corresponding to the switching time in FIG. 4), it is better to make the next light sources 16 and 17 emit light earlier. It is.

  That is, it is possible to shorten the waiting time until the objective lens 21 starts moving in the direction opposite to the present by emitting the next light sources 16 and 17 earlier, or to eliminate the waiting time. The time required to determine the type of the recording medium 15 can be shortened. FIG. 4 shows a state where there is no waiting time.

  For this reason, in this embodiment, when each of the DVD laser and the BD laser emits light, it is confirmed whether or not the entire S-shaped waveform has been detected. When this confirmation is completed, each laser diode (LD) is turned off. The next LD emits light immediately, and due to the time until the laser power stabilizes, before moving to the next operation (for example, switching the objective lens 21 from the upward direction to the downward direction) It is configured so that no waiting time occurs.

  In particular, the movement of the objective lens 21 is hardly stopped immediately after detection of the S-shaped waveform in consideration of the difference in the appearance position of the above-mentioned S-shaped waveform and surface blurring. Thereafter, it is very effective to stabilize the laser power of the light source by using the time until the moving direction of the objective lens 21 is switched (the raising or lowering of the objective lens 21 is completed).

  In the present embodiment, the light source for emitting light is switched after detecting the entire S-shaped waveform. However, the present invention is not limited to this configuration. For example, in the case of the present embodiment, the light source that emits light may be switched when the minimum value and the maximum value of the S-shaped waveform are detected. That is, as long as it is necessary to determine the type of the optical recording medium 15, the configuration may be such that the S-shaped waveform is detected and the light source is switched, or the light source is switched after detecting only half of the S-shaped waveform. It doesn't matter.

  In the present embodiment described above, the objective lens 21 is configured to move in the order of ascending, descending, and ascending. However, the present invention is not limited to this, and various modifications can be made without departing from the object of the present invention. . That is, for example, the objective lens 21 may be configured to move in order of descending, ascending, and descending, or the objective lens 21 may not be configured to be sequentially moved up and down.

  Further, the light emission order of the light sources 16 and 17 is not limited to the configuration of the present embodiment and can be changed. However, when the light source is configured to emit light in the order of one of the two-wavelength light sources, one of the two-wavelength light sources, and the other of the two-wavelength light sources as in the present embodiment, the time required for switching the light sources is shortened as much as possible It is advantageous and preferable from the viewpoint.

  Furthermore, the number of light sources included in the optical disc apparatus 1 and the types of optical recording media 15 that the optical disc apparatus 1 can handle are not limited to the configuration of the present embodiment, and various changes can be made. However, the greater the number of light sources that the optical disc apparatus 1 has, the greater the effect of shortening the time, and the present invention is particularly useful in an optical disc apparatus having three or more light sources.

  In addition, as in the present embodiment, the optical disk apparatus 1 is not limited to a recording / reproducing apparatus, and may be, for example, an optical disk apparatus that performs only reproduction.

  The optical disk apparatus of the present invention is particularly configured to reduce the time required to determine the type of optical recording medium by devising the switching of the light emission of the light source. For this reason, it is very useful for a device having an optical disk drive corresponding to a plurality of types of optical recording media.

These are block diagrams which show the structure of the optical disk apparatus of this embodiment. These are the schematic diagrams of the optical system of the optical pick-up with which the optical disk device of this embodiment is provided. These are the flowcharts which showed the operation | movement in the case of discriminating the kind of optical recording medium with the optical disk apparatus of this embodiment. These are schematic diagrams shown for explaining the operation of discriminating the type of the optical recording medium in the optical disc apparatus of the present embodiment. These are schematic diagrams showing the operation of discriminating the type of optical recording medium by a conventional optical disc apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical disk apparatus 15 Optical recording medium 15a Recording surface 16 Light source (2 wavelength light source)
17 Light source (1 wavelength light source)
21 Objective Lens 22 Actuator 24 Photodetector (Photodetection Unit)

Claims (6)

A plurality of light sources that emit light beams of different wavelengths;
An objective lens for condensing the light beam emitted from the light source on the recording surface of the optical recording medium;
A light detector that receives reflected light reflected by the optical recording medium;
An actuator for moving the objective lens in a focus direction parallel to the optical axis direction,
When determining the type of the optical recording medium inserted in the apparatus,
Of the plurality of light sources, at least two are switched in order to emit light,
In each case, detection of a focus error signal obtained by processing the signal from the photodetection unit by moving the objective lens in the direction approaching the optical recording medium or moving away from the optical recording medium by the actuator. In an optical disk device that performs
The optical disc apparatus characterized in that the timing of switching the light emission of the light source is determined based on detection of an S-shaped waveform of the focus error signal.   2. The optical disc apparatus according to claim 1, wherein the light emission of the light source is switched immediately after the entire S-shaped waveform or a predetermined part of the S-shaped waveform is detected.   Switching of the light emission of the light source is performed after detecting the entire S-shaped waveform or a predetermined part of the S-shaped waveform and for detecting the focus error signal for the light source before switching. 2. The optical disc apparatus according to claim 1, wherein the optical disc apparatus is performed before the movement in the direction approaching the optical recording medium or the direction moving away from the optical recording medium is completed. A detector that detects the light output of the light beam emitted from the light source;
The movement of the objective lens by the actuator for detecting the focus error signal in the case of each light source is started after the light output is stabilized. The optical disc device according to any one of the above.   5. The optical disc apparatus according to claim 1, wherein the number of light sources to be switched is three or more. The light source includes a one-wavelength light source that emits only a light beam having a single wavelength, and a two-wavelength light source that emits a light beam having two wavelengths.
The order in which the light sources emit light is the order of a light source that emits one wavelength of the two-wavelength light source, the one-wavelength light source, and a light source that emits the other wavelength of the two-wavelength light source. The optical disc apparatus according to claim 1.

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