JP2002312973A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform stable APC of a recording beam at the time of recording on one recording medium, in an optical pickup device for reproduction and recording on two kinds of recording mediums of different specifications, and to avoid a deterioration in the optical performance of an optical spot caused by a partial omission in the optical flux of a recording beam entering an objective lens. SOLUTION: The device is equipped with a first light source, a second light source, a beam splitter that reflects a beam emitted from the first light source to make the beam enter a collimator lens and that transmits a beam emitted from the second light source to make the beam enter the collimator lens, an objective lens that converges the beam outgoing from the collimator lens on a recording medium, and a light receiving part for a monitor for monitoring the power of the beam emitted from the second light source. A part of the beam outgoing from the second light source is reflected by the beam splitter, and this reflected light is made incident on the near center of the light receiving part for the monitor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a plurality of types of recording media, for example, a DVD (digital versatile disc) and a CD (CD in the present invention).
The present invention relates to an optical pickup device for reproducing and recording on recording media of different standards such as a compact disc in a broad sense including a recordable CD).

[0002]

2. Description of the Related Art There is an optical disk apparatus in which reproduction and recording of two types of recording media (optical disks) having different standards are performed by the same optical pickup. For example, the same optical pickup reproduces a DVD, records a CD (records on a recordable CD such as a CD-R (CD recordable) or CD-RW (CD rewritable)), and reproduces (recordable CD). Playback, CD-ROM, CD-DA
(Reproduction of a reproduction-only CD such as (CD digital audio)) is known.

A beam having a wavelength of about 650 nm is used for reproducing a DVD, and a wavelength of about 780 is used for recording and reproducing a CD.
nm beam is used, so the optical pickup
Two light sources having different emission beam wavelengths are mounted. Further, such an optical pickup is also equipped with a monitoring light receiving unit for monitoring the power of a beam emitted from a light source for a CD, and based on a signal detected by the monitoring light receiving unit, a CD light is received. Control the recording power (beam power) during recording to an appropriate value (APC; autopower)
control).

FIG. 3 is a diagram showing a configuration of a conventional optical pickup device capable of reproducing a DVD and recording / reproducing a CD. In FIG. 3, reference numeral 11 denotes a DVD laser which emits a beam having a wavelength of about 650 nm for reproducing a DVD, and 12 denotes a laser having a wavelength of about 7 for recording / reproducing a CD.
A CD laser that emits an 80 nm beam, 13 is a beam splitter, 14 is a collimator lens, 15 is an objective lens, and 16 is an APC light receiving element.

In the configuration shown in FIG. 3, the beam emitted from the DVD laser 11 is reflected by the beam splitter 13 and enters the collimator lens 14, is converted into a parallel light beam by the collimator lens 14, and enters the objective lens 15.
The light is converged by the objective lens 15 to irradiate a light spot on the DVD. The beam emitted from the CD laser 12 passes through the beam splitter 13 and enters the collimator lens 14, is converted into a parallel light beam by the collimator lens 14, enters the objective lens 15, is converged by the objective lens 15, A light spot is irradiated on the CD.

[0006] The APC light receiving element 16 is optically arranged so that a part of the APC light receiving element 16 enters the peripheral portion (base) of the spread of the laser beam for CD transmitted through the beam splitter 13. The power of the CD recording beam emitted from the CD laser 12 and transmitted through the beam splitter 13 is monitored by the APC light receiving element 16 so that the recording power of the CD laser 12 is controlled to an appropriate value. Was.

[0007]

As described above, FIG.
In the prior art, the APC light-receiving element 16 detects light at a part of the periphery (base) of the spread of the CD laser beam transmitted through the beam splitter 13. This is because even if a part of the laser beam for CD is blocked by the APC light receiving element 16, the objective lens 1
This is because the optical performance (recording performance) of the light spot focused on the CD and illuminated on the CD is not deteriorated as much as possible. )
Light detection has to be performed.

However, when light detection is performed using a part of the periphery (base) of the spread of the CD laser beam, the signal level detected by the APC light-receiving element 16 is small, and the individual lasers There is a problem that the dispersion is large and an electrical offset is likely to occur, so that stable APC (auto power control) cannot be achieved. Further, the amount of light at the peripheral portion (base) of the spread of the laser beam is not linearly changed with respect to the laser power, but is also changed with temperature, which also makes it difficult to achieve stable APC. I was

In the control of the APC, the detection SN
In order to improve the APC, a sufficient light amount is required. However, the improvement of the detected light amount for APC and the securing of the optical performance of the light spot irradiated on the CD are a trade-off in the conventional technology. In order to secure a sufficient amount of received light with the APC light receiving element 16, the AP that blocks the laser beam for CD toward the objective lens 15
As the area of the light receiving element 16 for C increases, the missing portion of the light beam for recording increases, causing a problem that the optical performance (recording performance) of the light spot irradiated on the CD is greatly deteriorated.

[0010] Therefore, a technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and an object thereof is to reproduce and record two types of recording media having different standards. In the optical pickup device, the recording beam AP performed at the time of recording on one recording medium is used.
In C (auto power control), stable APC can be performed, and optical performance degradation of a light spot due to partial omission of a light beam of a recording beam incident on an objective lens can be avoided. It is in.

[0011]

In order to achieve the above object, the present invention provides a first light source and a second light source for emitting a beam having a wavelength different from the wavelength of the beam emitted from the first light source. A light source, a beam splitter that reflects a beam emitted from the first light source to enter the collimator lens and transmits a beam emitted from the second light source and enters the collimator lens; and a beam splitter emitted from the collimator lens. An objective lens for converging the reflected beam on the first recording medium corresponding to the first light source or the second recording medium corresponding to the second light source, and monitoring the power of the beam emitted from the second light source. An optical pickup device provided with a light receiving unit for monitoring, a part of a beam emitted from the second light source is reflected by a beam splitter, and this reflected light is As is incident on a substantially central portion of the terpolymer light receiving unit, configured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a DV according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of an optical pickup device that enables reproduction of D and recording and reproduction of a CD. In FIG. 1, 1 is
The wavelength for reproducing DVD is approximately 630 nm to 670 n
a laser for DVD that emits a beam of m, a laser for CD that emits a beam having a wavelength of approximately 765 nm to 805 nm for recording / reproducing a CD, 3 a beam splitter, 4 a collimator lens, 5 an objective lens , 6 is AP
It is a light receiving element for C.

In this embodiment, the APC light receiving element 6
A part of the CD recording laser beam emitted from the CD laser 2 to the beam splitter 3 is disposed at a position facing the DVD laser 1 with the beam splitter 3 interposed therebetween. The light is reflected by 3a and input to the APC light receiving element 6. At this time, the light reflected by the beam splitter 3 is made to enter a substantially central portion of the APC light receiving element 6.

In the configuration of this embodiment shown in FIG.
The beam emitted from the VD laser 1 is reflected by the beam splitter 3 and enters the collimator lens 4, is converted into a parallel light beam by the collimator lens 4, enters the objective lens 5, is converged by the objective lens 5, and is converged on the DVD. Irradiate a light spot.

The beam emitted from the CD laser 2 is guided to the beam splitter 3, and most of the beam passes through the beam splitter 3 and enters the collimator lens 4.
The collimator lens 4 forms a parallel light beam, enters the objective lens 5, converges by the objective lens 5, and irradiates a light spot on the CD.

The CD emitted from the CD laser 2
The recording laser beam is guided to the beam splitter 3, a part of which is reflected by the reflection film 3 a of the beam splitter 3, is incident on a substantially central portion of the APC light receiving element 6, and detects the amount of light (recording laser beam). Power detection). As described above, when the detection laser beam is made to enter substantially the center of the APC light receiving element 6, the center C of the intensity distribution of the laser light as shown in FIG. Therefore, compared with the conventional case where the light amount is detected at the peripheral portion (base) of the spread of the laser beam, the light amount is excellent in terms of the detected light amount.
Fluctuations in the amount of light due to temperature changes are also reduced, and stable APC with little electrical offset and fluctuations can be achieved.

The polarization component of the light detected by the APC light receiving element 6 is set to be a P-polarization component. The reason for this is that the laser emission component is usually dominated by the P component, and the laser beam emitted from the objective lens 5 is also dominated by the P component. This is because the more accurate monitoring of the recording power can be achieved by using the P polarization component.

In order to perform detection with a P-polarized component as described above, the reflection film 3a of the beam splitter 3 has a reflectance Rp with respect to the P component of the laser beam having the CD recording beam wavelength.
Is set to approximately 1 to 10%, whereby A
A sufficient amount of light necessary for detection can be supplied to the PC light receiving element 6 and a sufficient amount of light can be supplied to the objective lens 5. Therefore, the loss of the light amount of the recording beam incident on the objective lens 5 can be suppressed, and a sufficient recording power can be secured.
As described above, the performance of the light spot is not degraded due to the lack of a part of the recording light beam.

[0020]

As described above, according to the present invention, in an optical pickup device for reproducing or recording two types of recording media having different standards, an APC (auto power) of a recording beam performed when recording on one recording medium is performed. control), it is possible to perform stable APC, and due to a partial lack of the light beam of the recording beam incident on the objective lens,
It is possible to avoid optical performance degradation of the light spot.

[Brief description of the drawings]

FIG. 1 shows DVD playback and C according to an embodiment of the present invention.
FIG. 3 is an explanatory diagram illustrating a configuration of an optical pickup device that enables recording and reproduction of D.

FIG. 2 is an explanatory diagram showing an intensity distribution of laser light emitted from a CD laser.

FIG. 3 shows a conventional technology for reproducing a DVD and recording a CD.
FIG. 3 is an explanatory diagram illustrating a configuration of an optical pickup device that enables reproduction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 DVD laser 2 CD laser 3 Beam splitter 3a Reflective film 4 Collimator lens 5 Objective lens 6 APC light receiving element

Claims (4)

[Claims] A first light source; a second light source that emits a beam having a wavelength different from a wavelength of a beam emitted from the first light source; and a beam that reflects the beam emitted from the first light source. A beam splitter that transmits a beam emitted from the second light source and enters the collimator lens, and a beam emitted from the collimator lens corresponds to the first light source. An objective lens that converges on a first recording medium or a second recording medium corresponding to the second light source, and a monitoring light receiving unit that monitors the power of a beam emitted from the second light source. In the optical pickup device, a part of the beam emitted from the second light source is reflected by the beam splitter, and the reflected light is received by the monitor receiver. The optical pickup apparatus is characterized in that so as to be incident at a substantially central portion of the parts. 2. The optical pickup device according to claim 1, wherein the light receiving section for monitoring is arranged at a position facing the first light source with the beam splitter interposed therebetween. 3. The optical pickup device according to claim 1, wherein the light receiving section for monitoring detects a P component of a polarization component of light. 4. The apparatus according to claim 1, wherein the first light source has a wavelength of about 630 for DVD playback.
The second light source emits a beam having a wavelength of approximately 765 nm to 805 nm for CD recording.
An optical pickup device which emits m beams, and wherein the beam splitter has a reflection film having a reflectance of approximately 1 to 10% with respect to a CD recording wavelength.