JP2003233927A - Optical pickup device and optical disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup device capable of constructing an optimum optical system for respective semiconductor laser beams different in wavelength, thereby realizing its miniaturization and high-quality writing even in using a light source unit mounted with a plurality of semiconductor laser chips in the same package. <P>SOLUTION: A light source unit 5, in which a plurality of chips of semiconductor laser beams 2, 3 that emit laser beams different in wavelengths in nearly the same direction in are incorporated in the same package 4, is provided with an inclined face 11, on which a coating film having a wavelength selection function is formed, and a reflection inclined face 12 which is tilted at an angle different from that of the inclined face 11 and which reflects a laser beam. Thus, it becomes possible to align the optical axes of laser beams different in wavelength with the optical axis of an objective lens 7, thereby constructing the optimum optical system for respective semiconductor laser beams 2, 3, and realizing its miniaturization. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device and an optical disc device provided with a plurality of light sources that emit laser beams having different wavelengths.

[0002]

2. Description of the Related Art In recent years, in the field of optical disk devices, in addition to the conventional CD system, the development of a DVD system having a large storage capacity
There is a remarkable spread. In this case, CD system and DVD
The light source wavelength used is different from that of the system (for example, the former is 7
80 nm and 650 nm for the latter), so optical disc devices or optical pickup devices are generally used exclusively for CDs, DVDs.
It is basically configured to be dedicated to the system.

However, this is not compatible with the CD system and the DVD system and requires separate drive devices, which is inconvenient for general users.

Under these circumstances, there has been proposed an optical pickup device or an optical disc device which is provided with a plurality of light sources for emitting laser beams having different wavelengths so as to be compatible with each other.

As an example, FIG. 6 shows a conventional structure of an optical pickup device compatible with two wavelengths. Semiconductor laser unit 10 which is selectively driven to emit laser beams having different wavelengths
The luminous fluxes from the reference numerals 1 and 102 are collimator lenses 10 respectively.
The light beams are converted into parallel light fluxes by 3, 104, combined by the dichroic prism 105, and condensed by the objective lens 106, so that the optical disc 107 is irradiated with a minute spot. The reflected light from the optical disc 107 passes through the objective lens 106 again and returns to the inside of the semiconductor laser units 101 and 102. The optical disk 10 returned inside the semiconductor laser units 101 and 102.
Light reflected from the semiconductor laser units 101, 10
The light is diffracted by a hologram element (not shown) attached to No. 2 and is received and detected by a light receiving element (not shown).
Then, by calculating based on the detection result of the light receiving element, it is detected as a servo control signal or a recording or reproducing signal, and the position control of the spot is performed by this.

In such a conventional example, since the light sources are the separate units 101 and 102 depending on the wavelength, an optical element (a dichroic prism 105 in the illustrated example) for combining the two light sources is required. The structure of the pickup device was complicated and the area was increased.

In consideration of such a point, recently, a semiconductor laser having two light sources built in one package has been developed to solve these problems. FIG. 7 shows an example of the configuration in principle. For example, 780 nm, 65
A light source unit 114 in which chips of two semiconductor lasers 111 and 112 that emit laser beams of different wavelengths such as 0 nm in substantially the same direction are incorporated in the same package 113.
Are provided, and the laser light emitted from these semiconductor lasers 111 and 112 is configured to be focused and irradiated onto the optical disc 117 via the common collimator lens 115 and the objective lens 116.

[0008]

However, even if the semiconductor lasers 111 and 112 for emitting laser beams having different wavelengths are incorporated in the same package 113,
The two semiconductor lasers 111 and 112 are physically several tens of tens.
The light emitting points are separated by about several hundred μm. For this reason, when the optical axis of one laser beam is optically optimized for the light flux after passing through the collimator lens 115, the other laser beam is misaligned and aberration is deteriorated, resulting in the problem. The spot quality on the optical disc 107 deteriorates, and a problem arises in the writing quality especially in a writing system that requires high accuracy.

According to the present invention, even when a light source unit in which a plurality of semiconductor laser chips are mounted in the same package is used, an optimum optical system can be constructed for the semiconductor laser of each wavelength. It is an object of the present invention to provide an optical pickup device and an optical disc device that can be downsized and can perform high quality writing.

[0010]

According to another aspect of the present invention, there is provided an optical pickup device comprising: an objective lens for focusing and irradiating a laser beam onto an optical recording medium; and a plurality of laser beams for emitting different wavelength laser beams in substantially the same direction. A light source unit in which a semiconductor laser chip is incorporated in the same package, a collimator lens arranged on a common optical path of laser light emitted from the plurality of semiconductor lasers, and converting the laser light into a parallel light flux, An optical element having an inclined surface on which a coating film having a wavelength selection function is formed for these laser beams converted into parallel light flux by a collimator lens, and a wavelength of the inclined surface inclined at a different angle from the inclined surface. A reflecting inclined surface for reflecting the laser beam of the other wavelength selected by the selecting function, and one of the inclined surfaces selected by the wavelength selecting function. The length of the laser beam optical axis with the laser beam of the other wavelength reflected by the reflection inclined surface and the optical axis and to align the optical axis of the objective lens.

Therefore, by combining an inclined surface on which a coat film having a wavelength selection function is formed and a reflective inclined surface which reflects laser light by being inclined at an angle different from that of the inclined surface, lasers of different wavelengths are combined. It becomes possible to match the optical axes of the lights with the optical axis of the objective lens, and an optimal optical system can be configured for each semiconductor laser, and miniaturization can be achieved.

According to a second aspect of the present invention, in the optical pickup device according to the first aspect, the wavelength selection function of the coat film reflects almost 100% of the laser light of the one wavelength and the wavelength of the other wavelength. It has a function of transmitting almost 100% of laser light.

Therefore, in separating the laser beams of different wavelengths by the wavelength selecting function in the optical component, the light quantity loss can be minimized in both reflection and transmission.

According to a third aspect of the present invention, in the optical pickup device according to the second aspect, the optical element is a wedge-shaped optical element which integrally has the inclined reflecting surface together with the inclined surface.

Therefore, in realizing the optical pickup device according to the second aspect of the present invention, it is possible to reduce the number of parts by constructing as a wedge-shaped optical element including the inclined reflection surface, which is also advantageous for downsizing. Become.

According to a fourth aspect of the present invention, in the optical pickup device according to the third aspect, the wedge-shaped optical element is provided immediately below an actuator that drives the objective lens, and the laser light emitted from the light source unit is used as the objective. Also serves as a rising mirror that leads to the lens.

Therefore, in realizing the optical pickup device according to the third aspect of the present invention, the wedge-shaped optical element can also be used as a rising mirror to achieve further miniaturization.

An optical disk device according to a fifth aspect of the invention is
5. A rotation drive mechanism for rotating an optical recording medium, and a laser beam for converging and irradiating the optical recording medium with laser light.
Any one of the optical pickup device and a light source driving unit that selectively drives a plurality of semiconductor lasers in a light source unit of the optical pickup device according to the type of the optical recording medium.

Therefore, since the optical pickup device according to any one of claims 1 to 4 is provided, the objective lens can be selectively driven by the semiconductor laser used depending on the type of the optical recording medium. Since there is no optical axis deviation with respect to, it is possible to perform a high-quality and stable writing operation.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of the present invention.
And it demonstrates based on FIG. The optical pickup device 1 of the present embodiment is configured as a two-wavelength optical pickup device compatible with CD / DVD systems.

First, a semiconductor laser 2 for emitting a laser beam having a wavelength of 780 nm for a CD system and a wavelength 650 for a DVD system.
A light source unit 5 in which a chip with a semiconductor laser 3 that emits a laser beam of nm is built in the same package 4 is provided. Although these semiconductor lasers 2 and 3 are arranged extremely close to each other, they physically have emission points that are separated by several tens to several hundreds of μm, and the emission directions of the laser beams are not the same but almost the same. Is configured to be. Further, this light source unit 5 also has a built-in diffraction grating and a light receiving element corresponding to each semiconductor laser, similarly to the case of the hologram laser unit, and also serves as a light receiving system.

On the other hand, an objective lens 7 for converging and irradiating the optical recording medium 6 with a laser beam is provided, and is movable by a tracking / focus actuator 8 in the tracking direction / focus direction.

Such a light source unit 5 and an objective lens 7
An optical system that guides the laser light emitted from the light source unit 5 side to the objective lens 7 and guides the return light reflected by the optical recording medium 6 from the objective lens 7 side to the light source unit 5 side. It is provided. This optical system will be described. First, a collimator lens 9 is provided on the common optical path of the semiconductor lasers 2 and 3 for converting any laser light into a parallel light flux. Further, an optical element 10 having a parallel plate configuration is arranged on the common optical path subsequent to the collimating lens 9. The optical element 10 is arranged so as to be inclined such that the surface facing the light source unit 5 is an inclined surface 11 having a predetermined angle, and the inclined surface 11 is arranged with respect to the wavelength of the laser light of the semiconductor lasers 2 and 3. A coat film having a wavelength selection function is formed. The wavelength selection function of this coat film is, for example, as shown in FIG.
As shown in, almost 100% of the laser light of one wavelength (780 nm) is reflected, and the other wavelength (650 nm)
The laser light has a characteristic of transmitting almost 100%.

Further, the laser beam of the other wavelength (650 nm) that is inclined by an angle different from that of the inclined surface 11 and is selected by transmission in the wavelength selection function of this inclined surface 11 is matched with the optical axis of the objective lens 7. An optical element 13 made of a parallel plate having a reflection slanting surface 12 for reflecting the light is disposed in the subsequent stage of the optical element 10.

In addition, one wavelength (78) selected by reflection in the wavelength selection function of the inclined surface 11 of the optical element 10 is used.
0 nm) laser light is reflected twice to match the optical axis of the objective lens 7. Two optical elements 14 and 1 having a parallel plate configuration.
5 are provided. The optical element 15 has a half mirror configuration.

In such a structure, the semiconductor laser 2
The laser light emitted from the laser beam is converted into a parallel light beam by the collimator lens 9, and then reflected by the inclined surface 11 of the optical element 10 by almost 100%.
It is reflected by 5 and guided to the optical axis of the objective lens 7 and is irradiated with the optical recording medium 6 by the condensing action thereof. Therefore, the laser beam emitted from the semiconductor laser 2 can be regulated so as to match the optical axis of the objective lens 7 by the inclination angle of the inclined surface 11 of the optical element 10 and the inclination angles of the optical elements 14, 15. A write operation can be performed. Even when the light is reflected by the inclined surface 11 of the optical element 10, there is almost no light amount loss because the reflection is almost 100%.

On the other hand, the laser light emitted from the semiconductor laser 3 is converted into a parallel light flux by the collimator lens 9, and then transmitted through the inclined surface 11 of the optical element 10 by almost 100%, and further the reflected inclined surface of the optical element 13. It is reflected by 12 and guided to the optical axis of the objective lens 7, and is irradiated with the optical recording medium 6 by receiving the condensing function. Therefore, the laser light emitted from the semiconductor laser 3 is not affected by the optical element 10 for the semiconductor laser 2, and only the tilt angle of the reflection tilt surface 12 of the optical element 13 tilted at a different angle allows the objective. It can be specified so as to match the optical axis of the lens 7, and a stable writing operation can be performed. Even when the light is transmitted through the inclined surface 11 of the optical element 10, since the light is almost 100% transmitted, there is no light amount loss.

A second embodiment of the present invention will be described with reference to FIG. The same parts as those shown in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted (the same applies to the following embodiments).

In the optical pickup device 1 of the present embodiment, in place of the optical elements 10 and 13 having the parallel plate configuration, the surface side facing the light source unit 5 is the inclined surface 11 having the coat film having the wavelength selection function, The wedge-shaped optical element 21 integrally having the other surface side as the reflection inclined surface 12 is used as an optical element. Reference numeral 22 is a rising mirror that guides the laser light emitted from the light source unit 5 and reflected by the inclined surface 11 and the reflective inclined surface 12 to the objective lens.

In such a structure, the semiconductor laser 2
The laser light emitted from the collimator lens 9 is converted into a parallel light flux, and then the inclined surface 11 of the wedge-shaped optical element 21.
At about 100%, further reflected by the rising mirror 22 and guided to the optical axis of the objective lens 7,
The optical recording medium 6 is irradiated with the light collecting action. Therefore, the laser beam emitted from the semiconductor laser 2 can be regulated so as to match the optical axis of the objective lens 7 by the inclination angle of the inclined surface 11 of the wedge-shaped optical element 21, and a stable writing operation can be performed. be able to. Optical element 2
Almost 100% even when reflected on the inclined surface 11 of 1.
Since it is a reflection, there is no light loss.

On the other hand, the laser light emitted from the semiconductor laser 3 is converted into a parallel light flux by the collimator lens 9, and thereafter, approximately 100 at the inclined surface 11 of the wedge-shaped optical element 21.
%, Further reflected by the reflecting inclined surface 12, further reflected by the rising mirror 22, and the objective lens 7
Of the optical recording medium 6 by being guided to the optical axis of
Is irradiated. Therefore, the laser light emitted from the semiconductor laser 3 is not affected by the inclined surface 11 for the semiconductor laser 2, and only the inclination angle of the reflection inclined surface 12 inclined at different angles causes the light of the objective lens 7 to be emitted. It can be specified to match the axis, and a stable write operation can be performed. Inclined surface 1 of wedge-shaped optical element 21
Even when the light is transmitted in No. 1, since it is almost 100% transmitted, there is no light amount loss.

A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the wedge-shaped optical element 21 described above is used.
Is arranged directly below the actuator 8 that drives the objective lens 7, so that it also functions as a raising mirror that guides the laser light emitted from the light source unit 5 to the objective lens 7. In order to facilitate the arrangement of the wedge-shaped optical element 21 and the like, here, the right-angle prism 23 is used.
Is formed as a composite element with a wedge-shaped optical element 21.

The case of this embodiment is similar to the case of the above-described embodiments, but in particular, the optical pickup device 1 is further miniaturized by making the wedge-shaped optical element 21 also serve as the raising mirror. can do.

A fourth embodiment of the present invention will be described with reference to FIG. In this embodiment, a light source unit 5 incorporating a chip of the semiconductor laser 2 for emitting a laser beam having a wavelength of 780 nm for a CD system and the semiconductor laser 3 for emitting a laser beam having a wavelength of 650 nm for a DVD system as described above is provided. An example of application to an optical disk device that includes the optical pickup device 1 having the optical pickup device 1 and can be commonly used for a CD / DVD optical recording medium 6 will be described. More specifically, the optical recording medium 6 is a CD-
This is an example of an optical disc device in which ROM, CD-R, CD-RW, and DVD-ROM can be used.

In FIG. 5, the optical recording medium 6 is rotationally driven by a spindle motor 31 which constitutes a main part of a rotational driving mechanism. The spindle motor 31 is controlled by the motor driver 32 and the servo means 33 so that the linear velocity becomes constant, for example. This linear velocity can be changed stepwise. The optical pickup device 1 has a built-in light receiving element and a position sensor in addition to the corresponding optical systems such as the semiconductor lasers 2 and 3 and the objective lens 7 described above, the tracking / focus actuator 8, and the like. The optical recording medium 6 is irradiated with laser light from the driven semiconductor laser 2 or 3. Further, this optical pickup device 1 can be moved in the sledge direction by a seek motor (not shown). These tracking / focus actuator 8 and seek motor are
Based on the signals obtained from the light receiving element and the position sensor, the motor driver 32 and the servo means 33 control so that the spot of the laser light is located at a target position on the optical recording medium 6.

At the time of reading, the reproduction signal obtained by the optical pickup device 1 is amplified by the read amplifier 34 and binarized, and then the CD / DVD decoder 35.
Entered in. The input binarized data is this CD /
In the DVD decoder 35, the EFM (Eight to Fou)
rteen Modulation) Demodulated. The recorded data is EFM-modulated by collecting 8 bits at a time.
With this EFM modulation, 8 bits are converted to 14 bits,
Three combined bits are added to make a total of 17 bits.
In this case, the combined bits are the previous "1" and "0".
Are numbered to be equal on average. This is referred to as "suppression of DC component", and the fluctuation of the slice level of the reproduction signal that has been DC cut is suppressed.

The demodulated data is subjected to deinterleaving and error correction processing. Then this data is
The data is input to the CD / DVD-ROM decoder 36, and error correction processing is further performed to improve the reliability of the data. The data that has been subjected to the error correction processing twice as described above is temporarily stored in the buffer RAM 38 by the buffer manager 37 and is stored as sector data in a state where it is sent to a host computer (not shown) via the ATAPI / SCSI interface 39. It is transferred all at once. In the case of music data, the data output from the CD / DVD decoder 35 is the D / A converter 4
0, and is taken out as an analog audio output signal Audio.

At the time of writing, ATAPI / SCS
The data sent from the host computer through the I interface 39 is temporarily stored in the buffer RAM 38 by the buffer manager 37. And
The write operation is started with a certain amount of data accumulated in the buffer RAM 38. In this case, however, the laser spot must be positioned at the write start point before that. This point is obtained by the wobble signal previously recorded on the optical recording medium 6 due to the meandering of the track.

The wobble signal includes absolute time information called ATIP, and this information is extracted by the ATIP decoder 41. Further, the sync signal generated by the ATIP decoder 41 is input to the CD encoder 42, which enables the writing of data to an accurate position on the optical recording medium 6. Buffer RAM38
Data is subjected to error correction code addition and interleaving in the CD-ROM encoder 43 and the CD encoder 42, and is transmitted via the laser controller 44 for the CD-R / RW and the semiconductor laser 2 in the optical pickup device 1. , Is recorded on the optical recording medium 6.

The overall control of such an optical disk device is controlled by a CPU 47 which is provided with a ROM 45 and a RAM 46 and is configured as a microcomputer.
When the optical recording medium 6 which is a DVD-ROM is loaded, the semiconductor laser 3 in the optical pickup device 1 is caused to emit light by the laser controller 48 for DVD, and the reproducing operation for the optical recording medium 6 is executed. Therefore, the laser controllers 44 and 48 and the CPU 47 function as a light source driving unit that selectively drives the semiconductor lasers 2 and 3 in the light source unit 5 according to the type of the optical recording medium 6.

Therefore, according to the optical disk device of the present embodiment, since the optical pickup device 1 as described above is provided, the semiconductor lasers 2 and 3 used according to the type of the optical recording medium 6 are selectively driven. Even with the configuration described above, since there is no optical axis deviation with respect to the objective lens 7, it is possible to perform high-quality and stable writing operation and the like.

In the present embodiment, the description has been given assuming that the DVD system has only the reproducing function.
The same can be applied to the case where the D system has a writing function.

[0043]

According to the optical pickup device of the first aspect of the invention, the inclined surface on which the coating film having the wavelength selection function is formed and the inclined surface are inclined at a different angle to reflect the laser beam. Since it is combined with the reflective inclined surface, it becomes possible to align the optical axes of the laser beams of different wavelengths with the optical axis of the objective lens, and to configure an optimal optical system for each semiconductor laser. It is also possible to reduce the size.

According to the second aspect of the present invention, in the optical pickup device of the first aspect, when the laser beams of different wavelengths are separated by the wavelength selecting function in the optical component, the light amount is reflected or transmitted. The loss can be minimized.

According to the invention described in claim 3, in realizing the optical pickup device described in claim 2, since it is configured as a wedge-shaped optical element including the inclined reflection surface, the number of parts can be reduced, and the size is small. It is also advantageous in terms of realization.

According to the invention described in claim 4, in realizing the optical pickup device according to claim 3, the wedge-shaped optical element also serves as a rising mirror, so that further miniaturization can be achieved. You can

According to the optical disk device of the invention described in claim 5, since the optical pickup device according to any one of claims 1 to 4 is provided, the semiconductor laser to be used is selectively used according to the type of the optical recording medium. Even in the selective driving configuration, since there is no optical axis deviation with respect to the objective lens, it is possible to perform high-quality and stable writing operation.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an optical pickup device according to a first embodiment of the present invention.

FIG. 2 is a characteristic diagram showing reflection / transmission characteristics according to wavelength.

FIG. 3 is a schematic configuration diagram showing an optical pickup device according to a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing an optical pickup device according to a third embodiment of the present invention.

FIG. 5 is a schematic block diagram showing an optical disc device according to a fourth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional optical pickup device.

FIG. 7 is a schematic configuration diagram showing another conventional optical pickup device.

[Explanation of symbols]

1 Optical pickup device 2,3 Semiconductor laser 4 packages 5 Light source unit 6 Optical recording media 7 Objective lens 8 actuators 9 Collimating lens 10 Optical element 11 inclined surface 12 Reflective inclined surface 21 Wedge-shaped optical element 31 rotation drive mechanism 44,48 Light source driving means

Continued front page    F-term (reference) 5D119 AA01 AA41 BA01 BB01 BB04                       EC45 EC47 FA08 JA17 JA26                       JA57 LB05                 5D789 AA01 AA41 BA01 BB01 BB04                       EC45 EC47 FA08 JA17 JA26                       JA57 LB05

Claims (5)

[Claims] 1. An objective lens for converging and irradiating a laser beam toward an optical recording medium, and a light source unit in which a plurality of semiconductor laser chips emitting laser beams of different wavelengths in substantially the same direction are incorporated in the same package. A collimating lens arranged on a common optical path of the laser beams emitted from the plurality of semiconductor lasers to convert the laser beams into parallel light beams; and a wavelength selection for the laser beams converted into parallel light beams by the collimator lens. An optical element having an inclined surface on which a coat film exhibiting a function is formed, and a reflection inclined surface which is inclined at an angle different from that of the inclined surface and reflects laser light of the other wavelength selected by the wavelength selection function of the inclined surface And, the optical axis of the laser beam of one wavelength selected by the wavelength selection function of the inclined surface and the other of the other reflected by the reflective inclined surface Long optical pickup apparatus of the laser light and the optical axis so as to align the optical axis of the objective lens. 2. The wavelength selection function of the coating film is a function of reflecting substantially 100% of the laser light of the one wavelength and transmitting almost 100% of the laser light of the other wavelength. Optical pickup device. 3. The optical pickup device according to claim 2, wherein the optical element is a wedge-shaped optical element that integrally has the inclined reflecting surface together with the inclined surface. 4. The optical pickup according to claim 3, wherein the wedge-shaped optical element is provided immediately below an actuator that drives the objective lens, and also serves as a rising mirror that guides the laser light emitted from the light source unit to the objective lens. apparatus. 5. A rotation drive mechanism for rotating an optical recording medium, an optical pickup device according to claim 1, which condenses and irradiates laser light onto the optical recording medium, and the optical pickup device. An optical disc device, comprising: a light source driving unit that selectively drives a plurality of semiconductor lasers in the light source unit according to the type of the optical recording medium.