JP4026012B2 - Optical disk device - Google Patents

Description

  The present invention relates to an optical disc apparatus capable of recording data on an optical disc such as a CD and a DVD.

  Conventionally, there are a write-once optical disc (for example, CD-R) that can only record data and a rewritable optical disc (for example, CD-RW) that can record and erase data. With the widespread use of optical discs, optical disc devices capable of recording and erasing data on optical discs have become popular. The write-once and rewritable optical discs have the highest power density of laser light necessary for data recording due to their characteristics, followed by the power density during erasure and the power density during reproduction. For this reason, an optical disc apparatus capable of recording and erasing data emits a laser beam (LD), which is a light source at the time of recording or erasing, to emit a laser beam having a higher power than that at the time of reproduction. There was a problem.

Therefore, it is considered to use two LDs to suppress the power of laser light emitted from each LD and to reduce the deterioration rate of the LD. For example, as shown in Patent Document 1, two LDs are used, laser light is irradiated from two directions, ie, a direction perpendicular to the recording surface of the optical disc and a parallel direction, and the direction perpendicular to the recording surface. The laser beam emitted from the laser beam is focused on the data recording position on the optical disc, and the recording beam is irradiated with the laser beam from a direction parallel to the recording surface. In this case, the power density of the laser beam at the recording position is the sum of the power densities of the laser beams irradiated to the recording position by the two LDs, and the light emission amount of each LD can be suppressed. Therefore, the deterioration rate of each LD can be reduced.
Japanese Patent Laid-Open No. 10-302261

  However, when an LD for irradiating laser light from a direction parallel to the recording surface of the optical disk is provided as in Patent Document 1, the laser light emitted from the LD is irradiated from the inner peripheral side to the outer peripheral side of the optical disk. Is done. On the other hand, since data recording is performed on one track of the optical disk, the laser light irradiated from a direction parallel to the recording surface of the optical disk hardly contributes to the data recording. For this reason, there has been a problem that the LD that irradiates laser light from a direction parallel to the recording surface of the optical disk is not effectively used.

  An object of the present invention is to provide an optical disc apparatus capable of recording data by using two light sources to suppress deterioration of each light source and effectively using laser light emitted from each light source. is there.

  Another object of the present invention is to provide an optical disc apparatus that shortens the time required for erasing data recorded on the optical disc.

  The optical disc apparatus of the present invention has the following configuration in order to solve the above problems.

(1) In an optical disc apparatus provided with recording means for irradiating a laser beam emitted from a light source via an optical element to an optical disc set in a main body and recording data on the optical disc,
The recording means has two light sources,
The optical element of the recording means has a laser beam incident on the outer peripheral portion, and has a light diameter larger than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion. With optical properties to irradiate the beam,
Furthermore, one light source was arranged so that laser light was incident on the central part of the optical element, and the other light source was arranged so that laser light was incident on the periphery including the central part of the optical element.

  In this configuration, when the laser light emitted from one light source is condensed on the recording position of the optical disc via the optical element, the laser light emitted from the other light source is condensed on the recording position around the recording position. A beam having a diameter larger than that of the laser beam is irradiated. The power density of the laser beam at the recording position is the sum of the power densities of the laser beams emitted and irradiated from the two light sources. Therefore, the power of the laser beam emitted from each light source during data recording can be suppressed, and the deterioration rate of each light source can be reduced.

  In addition, the laser beam emitted from the other light source is not irradiated from the inner circumference side to the outer circumference side of the optical disc as in the prior art, but only to the periphery of the recording position. The useless laser light irradiation that does not contribute can be suppressed, and the other light source can be effectively used.

(2) recording means for irradiating a laser beam emitted from a light source via an optical element to an optical disk set in the main body, and recording data on the optical disk;
In an optical disc apparatus provided with erasing means for irradiating a laser beam emitted from a light source via an optical element to an optical disc set in a main body and erasing data recorded on the optical disc,
The recording means has two light sources,
The optical element of the recording means has a laser beam incident on the outer peripheral portion, and has a light diameter larger than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion. With optical properties to irradiate the beam,
Furthermore, one light source is arranged so that laser light is incident on the central part of the optical element, and the other light source is arranged so that laser light is incident on the periphery including the central part of the optical element, and,
The erasing means has two light sources, and the erasing optical element superimposes the laser beams incident from the two light sources to produce a beam having a light diameter across a plurality of tracks on the optical disk. Irradiate.

In this configuration, in addition to the configuration (1), an erasing unit is provided. When erasing data, the erasing unit superimposes the laser beams emitted from the two LDs and irradiates a beam having a light diameter extending over a plurality of tracks. By increasing the light diameter, the power density of the laser light applied to the track of the optical disk decreases. However, since the laser light emitted from the two light sources is superimposed, the data recorded on the optical disk A plurality of tracks can be irradiated simultaneously with laser light having a power density sufficient for erasing. Therefore, data recorded on a plurality of tracks can be erased simultaneously, and the time required for erasing data can be shortened.
(3) An optical disc provided with recording / erasing means for irradiating the optical disc set in the main body with a laser beam emitted from a light source via an optical element, recording data on the optical disc, and erasing the data. In the device
The recording / erasing means has two light sources, a recording optical element used for recording, and an erasing optical element used for erasing,
In addition, one light source is disposed so that laser light is incident on a central portion of the optical element, and the other light source is disposed so that laser light is incident on the periphery including the central portion of the optical element,
Furthermore, the optical characteristics of irradiating the laser beam incident on the outer periphery with a beam having a larger diameter than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion The erasing optical element that irradiates the optical disk with a light beam having a diameter that spans a plurality of tracks by superimposing the laser light incident from the two light sources, Has a switching function for switching according to recording and erasing of data on the optical disc.

  This configuration is a configuration in which the recording means and the erasing means of (2) are integrated, and the optical element to be used (optical element for recording or optical element for erasing) is switched between recording and erasing. . Thereby, there exists an effect demonstrated by said (1) and (2).

  According to the present invention, it is possible to suppress the power of the laser beam emitted from each light source at the time of data recording, and to reduce the deterioration rate of each light source. In addition, the laser beam emitted from the other light source is not irradiated from the inner circumference side to the outer circumference side of the optical disc as in the prior art, but only to the periphery of the recording position. The useless laser light irradiation that does not contribute can be suppressed, and the other light source can be effectively used. Furthermore, the time required for erasing data can be shortened.

  Hereinafter, an optical disk apparatus according to an embodiment of the present invention will be described.

  FIG. 1 is a diagram showing a configuration of a main part of an optical disc apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a pickup head, and 2 denotes an optical disk such as a CD or a DVD set in the main body. The pickup head 1 corresponds to the recording / erasing means referred to in claim 1 of the present invention. However, this also corresponds to the recording means referred to in claim 2 and the erasing means referred to in claim 3.

  The pickup head 1 is attached so as to be movable in the radial direction of the optical disc 2 and is moved by a thread motor (not shown), as in the known optical disc apparatus. The optical disk 2 is held on a turntable, and has a known configuration in which the optical disk 2 is rotated by rotating the turntable by a spindle motor (not shown). Although not shown in the figure, the optical disk device encodes data to be recorded on the optical disk 2, encodes the encoded data into the pickup head 1, and decodes data read from the optical disk 2 by the pickup head 1, A reproduction unit for outputting as a reproduction signal is provided. The pickup head 1 controls the power of the laser beam irradiated on the optical disc 2 based on the data input from the encoding.

  FIG. 2 is a diagram showing a configuration of a pickup head applied to the optical disc apparatus according to the embodiment of the present invention. In FIG. 2, reference numerals 11 and 12 denote laser diodes (LD) as light sources, and reference numerals 13 and 14 denote photodiodes (PD) that detect reflected light from the optical disk 2. As shown in the drawing, the laser beam emitted from the LD 11 has a smaller divergence angle than the laser beam emitted from the LD 12. The laser beam emission directions of the LDs 11 and 12 are different by 90 degrees as shown in the figure. Reference numeral 15 denotes a beam splitter that transmits the laser light emitted from the LD 11 and bends the laser light emitted from the LD 12 by approximately 90 degrees to match the irradiation direction of the laser light emitted from the LD 11 and 12. Reference numeral 16 denotes a half mirror that irradiates laser light emitted from the LDs 11 and 12 in a direction perpendicular to the recording surface of the optical disc 2. Reference numeral 17 denotes a collimator lens that converts the laser light bent by the half mirror 16 into parallel light, and 18 (18a, 18b) denotes an objective lens for irradiating the optical disk 2 with the laser light emitted from the LDs 11 and 12. . The objective lens 18 corresponds to the optical element referred to in the present invention. Reference numeral 19 denotes a beam splitter that guides reflected light from the optical disc 2 to the PDs 13 and 14.

  The pickup head 1 controls the power of the laser light emitted from the LD 11 based on the amount of light received by the PD 13 and controls the power of the laser light emitted from the LD 12 based on the amount of light received by the PD 14. At the time of reproduction, a change in the amount of received light in the PD 13 is output as a read signal (RF signal) of the optical disc 2, and tracking server control and focus servo control are performed based on the amount of received light in the PD 13. In order to perform the tracking server control and the focus servo control, the light receiving area of the PD 13 is divided into four parts in the vertical and horizontal directions. Since tracking server control and focus servo control are publicly known, description thereof is omitted here.

  The pickup head 1 is provided with two objective lenses 18a and 18b as shown in the figure. The objective lens 18a is used for recording and reproducing data, and the objective lens 18b is used for erasing data. . The objective lenses 18 a and 18 b are attached to a holder, and the switching unit 21 rotates the holder to position the objective lenses 18 a and 18 b on the side to be used above the collimator lens 17.

  Next, the two objective lenses 18a and 18b will be described. As shown in FIG. 3A, the objective lens 18a used at the time of data recording and reproduction is a lens having a larger curvature at the center portion than at the outer portion, and the focal length of the center portion is the outer peripheral portion. It is a lens having optical characteristics shorter than the focal length. The objective lens 18b is a general lens having a uniform curvature as shown in FIG. The LD 11 has a relatively small divergence angle, and when the objective lens 18a is positioned above the collimator lens 17, the emitted laser light is incident only on the central portion where the curvature of the objective lens 18a is large, and almost on the outer periphery thereof. It arranges so that it may not enter. On the other hand, the LD 12 has a larger divergence angle than the LD 11, and when the objective lens 18a is positioned above the collimator lens 17, the emitted laser light is not only in the central portion where the curvature of the objective lens 18a is large, but also in the outer periphery thereof. It arrange | positions so that it may inject into a part.

  Next, the operation at the time of data recording in the optical disk apparatus of this embodiment will be described. In the optical disc apparatus, the objective lens 18 a is positioned above the collimator lens 17. Switching of the objective lenses 18a and 18b positioned above the collimator lens 17 is performed by the switching unit 21. The optical disk apparatus uses the LD 11 as a recording light source and the LD 12 as a recording auxiliary light source when recording data. Specifically, the power of the laser beam emitted from the LD 11 is controlled according to the data recorded on the optical disc 2, and the power of the laser beam emitted from the LD 12 is set at a certain level (predetermined regardless of the data recorded on the optical disc 2. Record auxiliary level).

  During this recording, the laser beam emitted from the LD 11 is incident on the central portion of the objective lens 18 a via the beam splitter 15, the half mirror 16, and the collimator lens 17. On the other hand, the laser beam emitted from the LD 12 is incident not only on the central portion of the objective lens 18a but also on the outer peripheral portion thereof via the beam splitter 15, the half mirror 16, and the collimator lens 17. In the pickup head 1, based on the reflected light from the optical disk 2 received by the PD 13 at this time, the laser light incident on the central portion of the objective lens 18 a is formed on the optical disk 2 as shown in FIG. Tracking servo control and focus servo control are performed so that light is focused on the recording position of the track. As a result, the laser light incident on the outer peripheral portion of the objective lens 18a is irradiated not on the central portion but on the periphery including the recording position. The pickup head 1 controls the power of the laser beam emitted from the LD 12 to be the above-described recording assist level based on the amount of light received by the PD 14.

  Here, the recording assistance level will be described. This auxiliary recording level is lower than a recording level required when data is recorded on the optical disc 2 and an erasing level required when erasing data recorded on the optical disc 2. Therefore, there is no situation in which unnecessary data is recorded on the optical disc 2 or the recorded data is unnecessarily erased at a position other than the recording position where the laser beam of the auxiliary recording level is irradiated. .

  On the other hand, at the recording position, the laser beam incident on the central portion of the objective lens 18a and the laser beam incident on the outer peripheral portion of the central portion are overlapped and irradiated. For this reason, the power density of the laser beam applied to the recording position is the sum of the two laser beams. The power density of the laser light incident on the central portion of the objective lens 18a and condensed at the recording position can be changed by controlling the power of the laser light output from the LD 11. The pickup head 1 controls the power density of the laser beam emitted from the LD 11 according to the data to be recorded on the optical disc 2, thereby controlling the power density of the laser beam irradiated to the recording position. Record.

  As described above, since the optical disk apparatus of this embodiment is configured to irradiate the laser beams emitted from the two LDs 11 and 12 at the recording position, the laser beams emitted from the individual LDs 11 and 12 at the time of data recording are recorded. Power can be suppressed, and the degradation rate of the LDs 11 and 12 can be reduced. Further, the laser beam emitted from the LD 12 only irradiates the periphery of the recording position, and does not radiate from the inner circumference side to the outer circumference side as in the prior art. Therefore, the laser beam emitted from the LD 12 does not contribute to data recording on the optical disc 2. The laser beam emitted can be suppressed, and data can be recorded using the two LDs 11 and 12 effectively.

  Next, the operation at the time of data reproduction in the optical disk apparatus of this embodiment will be described. In the optical disc apparatus, the objective lens 18 a is positioned above the collimator lens 17. Switching of the objective lenses 18a and 18b positioned above the collimator lens 17 is performed by the switching unit 21 as described above. In addition, the optical disk apparatus uses the LD 11 as a light source for reproduction at the time of data reproduction, and does not use the LD 12 (does not emit laser light). For this reason, at the time of reproduction, only the laser light emitted from the LD 11 is incident on the central portion of the objective lens 18a via the beam splitter 15, the half mirror 16, and the collimator lens 17. Based on the reflected light from the optical disk 2 received by the PD 13 at this time, the pickup head 1 collects the laser light incident on the central portion of the objective lens 18a at the reproduction position of the track formed on the optical disk 2. Tracking servo control and focus servo control are performed so that light is emitted. Further, a read signal (RF signal) based on the reflected light from the optical disc 2 received by the PD 13 is output.

  Note that the power density of the laser light applied to the reproduction position is higher than the recording level necessary for recording data on the optical disc 2 and the erasing level necessary for erasing data recorded on the optical disc 2. Is also small.

  Finally, the operation at the time of erasing data in the optical disc apparatus of this embodiment will be described. In the optical disk device, the objective lens 18 b is positioned above the collimator lens 17. Switching of the objective lenses 18a and 18b positioned above the collimator lens 17 is performed by the switching unit 21 as described above. Even at the time of erasing, the laser light emitted from the LD 11 is incident on the central portion of the objective lens 18b, and the laser light emitted from the LD 12 is incident not only on the central portion of the objective lens 18b but also on the outer peripheral portion thereof. However, since the objective lens 18b is different from the objective lens 18a described above and has a uniform curvature, the laser light emitted from the LD 11 and the LD 12 is irradiated onto the optical disc 2 in a substantially overlapped state. The objective lens 18b has a relatively long focal length, and irradiates the recording surface of the optical disc 2 with a laser beam having a light diameter extending over a plurality of tracks as shown in FIG. The position irradiated with this laser beam is the erasing position.

  The power density of the laser beam irradiated to the erasing position is the sum of the power densities of the laser beams emitted from the LD 11 and LD 12 and irradiated. In other words, each of the LD 11 and LD 12 erases data recorded simultaneously on a plurality of tracks by outputting laser light in which the power density of the laser light irradiated to the erasing position is half of the erasing level. be able to. Further, since the laser beam is irradiated over a wide range of each track, the rotation speed of the optical disc 2 at the time of erasing can be increased. Therefore, it is possible to shorten the time required for erasing data. In addition, the light emission amount of each of the LDs 11 and 12 can be suppressed.

  As described above, the optical disk apparatus according to this embodiment can suppress the power of the laser beam emitted from each LD 11 and 12 during data recording, so that the deterioration rate of each LD 11 and 12 can be reduced. . Further, since the laser light emitted from the LD 12 is only irradiated around the recording position, it is possible to suppress unnecessary laser light irradiation that does not contribute to data recording, and the LD 12 can be effectively used. . Furthermore, the time required for erasing data can be shortened.

  In the above embodiment, the pickup head 1 is provided with the objective lenses 18a and 18b, and the objective lens 18a is used at the time of data recording and reproduction, and the objective lens 18b is used at the time of erasing data. As shown in the figure, two pickup heads 1 (1a, 1b) are provided, one pickup head 1a is provided with only the objective lens 18a, and the other pickup head 1b is provided with the objective lens 18b. The head 1a may be used, and the pickup head 1b may be used when erasing data. In this case, it is not necessary to provide the switching unit 21 described in the above embodiment in the pickup heads 1a and 1b.

  In the above-described embodiment, an example in which the optical element of the present invention is configured by the objective lenses 18a and 18b has been described. However, an optical element having the same optical characteristics as the objective lenses 18a and 18b, such as a hologram or a grating, is used. , 18b can be substituted.

It is a figure which shows the structure of the principal part of the optical disk apparatus which is embodiment of this invention. It is a figure which shows the structure of the pick-up head applied to the optical disk apparatus which is embodiment of this invention. It is a figure which shows the objective lens of a pick-up head. It is a figure explaining the laser beam irradiated at the time of recording with respect to an optical disk. It is a figure explaining the laser beam irradiated at the time of erasing with respect to an optical disk. It is a figure which shows the structure of the principal part of the optical disk apparatus which is another embodiment of this invention.

Explanation of symbols

1, 1a, 1b-pickup head 2-optical disc 11, 12-laser diode 18a, 18-objective lens 21-switching unit

Claims (3)

In an optical disc apparatus provided with a recording / erasing means for irradiating a laser beam emitted from a light source via an optical element to an optical disc set in a main body, recording data on the optical disc, and erasing data
The recording / erasing means has two light sources, a recording optical element used for recording, and an erasing optical element used for erasing,
In addition, one light source is disposed so that laser light is incident on a central portion of the optical element, and the other light source is disposed so that laser light is incident on the periphery including the central portion of the optical element,
Furthermore, the optical characteristics of irradiating the laser beam incident on the outer periphery with a beam having a larger diameter than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion The erasing optical element that irradiates the optical disk with a light beam having a diameter that spans a plurality of tracks by superimposing the laser light incident from the two light sources, An optical disc apparatus having a switching function for switching the data in accordance with recording and erasing of data on the optical disc. In an optical disc apparatus provided with a recording means for irradiating a laser beam emitted from a light source via an optical element to an optical disc set in a main body and recording data on the optical disc,
The recording means has two light sources,
The optical element of the recording means has a laser beam incident on the outer peripheral portion, and has a light diameter larger than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion. With optical properties to irradiate the beam,
Furthermore, one optical source is disposed so that laser light is incident on a central portion of the optical element, and the other light source is disposed so that laser light is incident on the periphery including the central portion of the optical element. A recording means for irradiating a laser beam emitted from a light source via an optical element to an optical disk set in a main body, and recording data on the optical disk;
In an optical disc apparatus provided with erasing means for irradiating a laser beam emitted from a light source via an optical element to an optical disc set in a main body and erasing data recorded on the optical disc,
The recording means has two light sources,
The optical element of the recording means has a laser beam incident on the outer peripheral portion, and has a light diameter larger than the laser beam incident on the central portion around the condensing position of the laser light incident on the central portion. With optical properties to irradiate the beam,
Furthermore, one light source is arranged so that laser light is incident on the central part of the optical element, and the other light source is arranged so that laser light is incident on the periphery including the central part of the optical element, and,
The erasing unit has two light sources, and the optical element of the erasing unit superimposes the laser beams incident from the two light sources to generate a beam having a light diameter across a plurality of tracks on the optical disk. An optical disk device for irradiation.

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