JP2004170480A - Optical component, optical pickup device using the optical component, and optical disk unit using the optical pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical component provided with a direction discrimination part to stabilize characteristic variance due to rotational arrangement of an optical component by making some optical component of the optical component itself uniform in one direction, an optical pickup device using the optical component, and an optical disk unit using the optical pickup device. <P>SOLUTION: The optical pickup device is provided with a housing 101, at least one or more light source units 201 and 202 which are fitted to the housing 101 and for irradiating an information recording surface of a disk with laser light, and an objective lens 307 which has a transmission/reflection surface transmitting or reflecting the laser light emitted by the light source units 201 and 202 and has a mark formed on the transmission/reflection surface at a circumferential edge position where the aberrations of the laser light transmitted or reflected by the transmission/reflection surface become minimum. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a CD (Compact Disk), a CD (Compact Disk) -R (Recordable) / RW (ReWritable), a DVD (Digital Versatile Disk) -ROM (Read Only Memory), and a DVD (Digital Radio (DRAM)). The present invention relates to an optical component that irradiates a laser beam to an optical disk such as an access memory, an optical pickup device for recording or reproducing information, and an optical disk device using such an optical pickup device.
[0002]
[Prior art]
2. Description of the Related Art In recent years, in the field of recording media, DVDs have been developed that have the same size as the diameter (12 cm) of a conventional CD on which audio or digital data is recorded, and yet are capable of high-density recording. Since the DVD has a high recording density, laser light having a wavelength (for example, 650 nm) shorter than the wavelength (for example, 780 nm) of light for reading data of the CD is required.
[0003]
As an optical disk device, a device capable of recording and reproducing both a CD system and a DVD system is desired. Thereby, as an optical pickup device using a light emitting element (laser element) that emits a laser beam of a predetermined wavelength, a first light source for CD (780 nm wavelength) and a second light source for DVD (650 nm wavelength) ) Have been developed.
[0004]
However, demands for high performance and miniaturization of optical disk devices have been remarkably increasing, and accordingly, strict design conditions have been imposed on optical pickup devices using such two types of light sources having different wavelengths. ing.
[0005]
In order to satisfy such severe conditions, conventionally, when mounting an optical component (for example, a collimator lens) on a housing that controls the outer shape of the optical pickup device, a space between the inner surface of the housing and the collimator lens is required. Also, there is provided an optical pickup device which restricts a rotational direction position of a collimator lens with respect to an optical axis of laser light emitted from a light emitting member and minimizes astigmatism of laser light transmitted through the collimator lens. . (For example, see Patent Document 1).
[0006]
[Patent Document 1]
JP 2002-32931 A (Page 3-10, FIG. 1)
[0007]
[Problems to be solved by the invention]
In such an optical pickup device, for example, with the miniaturization and thinning of the optical pickup device, in addition to the optical performance of each unit such as an optical element and an optical component, their arrangement and arrangement angle are also subject to great design constraints. Absorbing errors is an important factor in design. However, the arrangement and the arrangement angle of the optical components are affected by the accuracy and adjustment accuracy of the housing for positioning the optical components or the jigs and tools for assembling, and there is a limit to the mechanical adjustment drive from the distribution of variations.
[0008]
On the other hand, the optical performance of each single optical component also varies. For example, in a mold for generating an objective lens that focuses a laser beam on an information recording surface of an optical disc, there is a performance variation between cavities of the mold or within the same cavity, and particularly, a temperature of the mold. Because the directionality of the optical characteristics of the objective lens changes under such conditions, there is a case where the direction identification portion indicating the directionality of the optical characteristics is formed on the optical component on the mold and cannot be used as the identification portion. Therefore, in order to stably exhibit the optical performance of each single optical component, it is important to reduce the characteristic variation of each component.
[0009]
The present invention has been made to solve such a problem, and a mark (direction identification) is provided so that certain optical characteristics of optical components are aligned so as to be directed in one direction, and characteristics variation due to rotational arrangement of the optical components is stabilized. And an optical pickup device using the optical component, and an optical disc device using the optical pickup device.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a transmission / reflection surface for transmitting or reflecting the laser light emitted from a light source unit for irradiating the laser light, and the transmission / reflection transmitted or reflected on the transmission / reflection surface. A mark is formed at a peripheral position of the transmission / reflection surface where the aberration of the laser beam is minimized.
[0011]
With the above configuration, the mounting direction when the optical component is mounted on the housing is indicated, so that the mounting operator can easily work and the variation in the optical performance of the optical component alone can be reduced.
[0012]
In order to achieve the above object, the present invention provides a housing, at least one light source unit attached to the housing and irradiating a laser beam to an information recording surface of a disk, and a light source attached to the housing. A transmission / reflection surface for transmitting or reflecting the laser light emitted from the unit, and a mark formed at a peripheral position of the transmission / reflection surface where the aberration of the laser light transmitted or reflected through the transmission / reflection surface is minimized And an optical component provided.
[0013]
With the above configuration, when the optical component is attached to the housing, the mark is aligned with a predetermined direction of the housing, so that the variation in the optical performance of the optical component alone can be reduced, and stable performance can be secured. it can.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1A and 1B are configuration diagrams of an optical pickup device described in this embodiment, where FIG. 1A is a plan view and FIG. 1B is a side view. Hereinafter, description will be made with reference to both the drawings.
[0015]
That is, the first integrated optical unit 201 is attached to one side wall 102 of the housing 101. The first integrated optical unit 201 is a CD light source (first light source) that emits a laser beam having a wavelength of 780 nm.
[0016]
The first integrated optical unit 201 receives light reflected from the disk 400 by being diffracted by the hologram 301 and irradiating the hologram 301 with light. The first integrated optical unit 201 performs optical conversion to obtain a reproduction signal, a focusing error signal, and a tracking error signal. A vessel 20 is provided.
[0017]
Further, a second integrated optical unit 202 is attached to the other side wall 103 of the optical base 101. The second integrated optical unit 202 is a DVD light source (second light source) that emits a laser beam having a wavelength of 650 nm.
[0018]
As described above, the optical pickup device includes the first light source (for CD) and the second light source (for DVD). The laser light emitted from the first integrated optical unit 201 is emitted on a plane 104 of the housing 101 serving as an optical base in a direction substantially parallel to the plane 104, and is incident on the dichroic PBS 302 via the hologram 301.
[0019]
The laser light from the first integrated optical unit 201 travels straight through the dichroic PBS 302, passes through the collimator lens 303, and enters the reflection mirror (prism) 306.
[0020]
The light reflected by the reflection mirror 306 enters an objective lens 307 disposed above the reflection mirror 306. The light focused by the objective lens 307 is applied to a reflective layer (information recording surface) of the optical disc 400 located above the objective lens 307.
[0021]
The light reflected on the information recording surface of the optical disc 400 enters the dichroic PBS 302 via the objective lens 307 and the reflection mirror 306.
The reflected light that has entered the dichroic PBS 302 travels straight, is diffracted by the hologram 301, enters the photodetector 20 in the first integrated optical unit 201, and outputs the reproduction signal, the focusing error signal, and the tracking error signal. Provided for generation.
[0022]
The laser light emitted from the second integrated optical unit 202 is emitted on the plane 104 of the housing 101 in a direction substantially parallel to the plane 104, and enters the dichroic PBS 302 via the hologram 311.
[0023]
The laser light from the second integrated optical unit 202 is reflected inside the dichroic PBS 302, changed its direction, and enters the collimator lens 303. The laser light that has entered the collimator lens 303 enters a reflection mirror (prism) 306.
[0024]
The light reflected by the reflection mirror 306 enters an objective lens 307 disposed above the reflection mirror 306. The light focused by the objective lens 307 is applied to a reflective layer (information recording surface) of the optical disc 400 located above the objective lens 307.
[0025]
The light reflected on the information recording surface of the optical disc 400 enters the dichroic PBS 302 via the objective lens 307 and the reflection mirror 306.
The reflected light incident on the dichroic PBS 302 is reflected, diffracted by the hologram 311 and incident on the photodetector 21 in the second integrated optical unit 202, where the reproduced signal, the focusing error signal, and the tracking error signal are detected. Provided for generation.
[0026]
The objective lens 307 is held by a lens holder (not shown). The lens holder is supported by one end of a plurality of wires, and can be finely controlled in the focus direction and the tracking direction. The plurality of wires are held by a wire holder attached to the optical base 101.
[0027]
For example, a small permanent magnet for focusing control and a permanent magnet for tracking control are attached to the lens holder. A yoke coil for focusing control and a yoke coil for tracking control are arranged on the optical base in proximity to these permanent magnets. By supplying a focusing control signal and a tracking control signal to the focusing control yoke coil and the tracking control yoke coil, respectively, the objective lens 307 can be finely controlled in the focus control direction and the tracking control direction, respectively. .
[0028]
Next, the configuration of an optical disk device using the above-described optical pickup device will be described.
In FIG. 2, DT is a disk table holding the optical disk 400 as a storage medium. This disk table DT is driven to rotate by a disk motor controlled by a servo circuit.
[0029]
Reference numeral 100 denotes an optical pickup device, which irradiates a laser beam onto an information recording surface of an optical disk 400 held at a disk table DT and rotated at a predetermined speed, as described with reference to FIG. It takes in the reflected light reflected by the surface and outputs an electrical signal corresponding to the light intensity of the reflected light.
[0030]
The optical pickup device 100 moves along a guide rail 600 provided in a predetermined positional relationship with respect to the disk table DT in a direction perpendicular to the tangential direction of the track formed on the information recording surface of the optical disk 400 (radius of the optical disk 400). (I.e., tracking control direction). The optical pickup device 100 is reciprocated on a guide rail 600 by a linear motor.
[0031]
An output signal of the photodetector 20, which is built in the first integrated optical unit 201 of the optical pickup device 100 and receives reflected light from the optical disk 400, is transmitted to a signal processing circuit 701, a tracking control circuit 702, and a focusing control circuit 703. I will The signal processing circuit 701 executes an arithmetic process for reproducing information recorded on the optical disc 400.
[0032]
The tracking control circuit 702 generates a tracking error signal by performing arithmetic processing on a signal obtained from the optical disc 400, and generates a tracking control signal to be supplied to the tracking control yoke coil. The focusing control circuit 703 performs arithmetic processing on a signal obtained from the optical disc 400 to generate a focusing error signal, and generates a focusing control signal to be supplied to the focusing control yoke coil.
[0033]
The laser drive circuit 705 controls the power of the laser light of the first integrated optical unit 201 and the second integrated optical unit 202 according to a control signal from an APC (automatic power control) circuit (not shown). The APC circuit determines whether or not the input detection signal is a signal of a preset level, and supplies a control signal obtained based on the determination result to the laser driving circuit 705. . As a result, automatic control is performed so that the power of the output laser light or the amount of reflected light from the optical disc 400 falls within a predetermined standard range.
[0034]
In each of the first and second integrated optical units 201 and 202, a laser element that emits a laser beam having a predetermined wavelength is used. Further, the objective lens 307 can be moved by the lens holder in a direction perpendicular to the tangential direction of the track (radial direction of the optical disk 400) and in a laser beam passing direction (direction orthogonal to the information recording surface of the optical disk 400). It is supported by.
[0035]
The radial direction of the optical disc 400 is called a tracking control direction. The direction orthogonal to the information recording surface of the optical disc 400 is called a focusing control direction.
The tracking control circuit 702 generates a tracking control signal from the tracking error signal and supplies the tracking control signal to the tracking control yoke coil. The focusing control circuit 703 generates a focusing control signal from the focusing error signal and supplies the signal to the focusing control yoke coil.
[0036]
The operation timing of the entire circuit and the switching control of the operation conditions (parameters and the like) are set by a control signal from the system control unit 710. The optical disk device also includes a power supply device, a ROM (Read Only Memory) storing a program to be read when operating the device itself, data read from the optical disk 400, and data input from a host computer or the like. Also, a RAM (Random Access Memory) (work memory) for temporarily storing control data and the like is provided.
[0037]
In the above description, the operation at the time of reproducing information from the optical disk 400 has been described. However, it goes without saying that the device of the present invention can be applied to information recording on a RAM disk. At this time, the modulation of the laser drive circuit 705 is controlled according to the recording information, and the APC circuit is controlled so that the average power of the laser light reaches the recording level.
[0038]
FIG. 3 is a diagram showing an objective lens according to the embodiment of the present invention.
As shown in FIG. 3, two outer solid lines of the concentric circle are the outer shape of the objective lens 307, and the inner dotted line is an effective area of the objective lens 307. A small circle in the middle of these two circles is a mark (direction identification unit) 10. The direction identification unit 10 indicates the direction of astigmatism which is a part of the optical characteristic. The direction identification unit 10 is attached to the objective lens 307, and moves in one direction of the holder 12 for holding the objective lens 307. By assembling, the astigmatism characteristic of the optical pickup device can be obtained with reduced variation and stable. The edge 11 has a shape protruding toward the outer peripheral edge of the objective lens 307. The edge 11 is supported by a holder to hold the objective lens 307.
[0039]
Next, the direction identification unit will be described in more detail.
FIGS. 4A and 4B are views showing the irradiation state of the laser beam at that time when the X point and the Y point of the objective lens in FIG. 3 are respectively adjusted to the Z point of the holder.
The objective lens 307 is usually formed by a mold, but the optical performance of the objective lens 307 varies even in each cavity of the mold or in the same cavity. This is because, as described above, when the mold is removed under conditions such as the temperature of the mold, unevenness occurs in the objective lens 307, resulting in an uneven shape. If the objective lens 307 having a variation in optical performance is held by the holder 12 as it is, stable optical characteristics cannot be obtained.
[0040]
Therefore, before the objective lens 307 is held by the holder 12, the directionality of the optical characteristics of the objective lens 307 is confirmed. For example, the direction of the objective lens 307 is checked so that the distance until the laser beam transmitted through the objective lens 307 is focused on the information recording surface of the optical disc 400 is the longest.
[0041]
When the X point of the objective lens 307 in FIG. 3 is matched with the Z point of the holder 12 in FIG. 4, it is assumed that the distance until the laser beam is focused on the information recording surface is the longest. Further, it is assumed that the distance until the laser beam is focused on the information recording surface is shortest when the Y point of the objective lens 307 in FIG. 3 is matched with the Z point of the holder 12 in FIG. Actually, due to the characteristics of the lens, a point shifted by about 90 ° from the point where the distance is considered to be the longest is such that the distance becomes the shortest. If the X point is determined, the Y point is inevitably determined.
[0042]
As shown in FIG. 4A, a state where the Y point of the objective lens 307 and the Z point of the holder 12 are aligned to irradiate the laser beam onto the optical disc 400, and as shown in FIG. Looking at the state where the laser light is irradiated onto the optical disc 400 by matching the X point of the holder 12 and the Z point of the holder 12, it can be seen that the astigmatic difference H occurs. When the astigmatic difference H occurs, the astigmatism of the laser beam that has passed through the objective lens 307 increases, and good optical characteristics cannot be obtained.
[0043]
Next, the structure of the first integrated optical unit 201 or the second integrated optical unit 202 for irradiating laser light will be described with reference to FIG.
FIG. 5A is a configuration diagram illustrating the first integrated optical unit.
The first integrated optical unit 201 is provided with an opening 13 for irradiating laser light, and the laser light is irradiated through this opening 13. FIG. 5B is a cross-sectional view taken along line AA ′ of FIG. 5A. As shown in FIG. 5A, the opening 13 has a width P in the horizontal direction and a height Q in the height direction. Have. When the first integrated optical unit 201 is attached to the housing 101, the relationship between the width P and the height Q is always such that the width P> the height Q. FIG. 5C is a diagram showing a plan view of the first integrated optical unit 201 of FIG. 5A as viewed from the S direction and a side view as viewed from the T direction. As shown in FIG. 5C, when the laser beam is irradiated, the laser beam starts to be irradiated from a position slightly inside the opening 13 due to the influence of the width P in the plan view viewed from the S direction. Further, in the side view seen from the T direction, the irradiation of the laser beam starts from the vicinity of the opening 13 due to the influence of the height Q. That is, the laser light emitted from the first integrated optical unit 201 has a characteristic that the irradiation position is different depending on the shape of the opening 13, and this applies to any integrated optical unit. Then, since the irradiation positions are different, an astigmatic difference H 'is generated here as well.
[0044]
Therefore, in the present invention, since the astigmatic difference H due to the variation of the optical characteristics of the objective lens 307 alone and the astigmatic difference H ′ due to the shape of the opening of the first integrated optical unit 201 are generated, these astigmatic differences are used. The feature is that the direction identification unit 10 is attached in a direction that minimizes the astigmatism of the objective lens 307.
[0045]
The way of marking and the mark shape of the direction identifying unit 10 will be described below.
In FIG. 4B, when the X point of the objective lens 307 is set to the Z point of the holder 12, the distance until the laser beam reaches the information recording surface of the optical disc 400 is the longest, and FIG. In the plan view as seen from the S direction shown in FIG. Therefore, when the X point of the objective lens 307 is set in the U direction in FIG. 5C (when the distance until the laser beam reaches the optical disk is set to be the longest), the astigmatic difference is canceled. Therefore, the direction discriminating unit 10 is marked at the point X because the dispersion of the optical characteristics can be eliminated.
[0046]
That is, when the first integrated optical unit 201 and the like are mounted on the housing 101, the first integrated optical unit 201 and the like are usually mounted in a fixed direction, and the opening 13 of the first integrated optical unit 201 is maintained in a relationship of width P> height Q. It is attached. Then, the operator checks the U direction of the first integrated optical unit 201 as shown in FIG. 5C, and identifies the direction at the X point of the objective lens 307 which has been inspected and has the longest known distance. Mark the part 10.
[0047]
When marking the direction identification unit 10, it is preferable to use a paint that can be removed later by heat. If the direction identification unit 10 is left near the edge 11 of the objective lens 307 as it is, the optical characteristics will be affected when it becomes necessary to increase the effective area of the objective lens 307 to the outer shape limit due to further miniaturization, for example. . Therefore, it is desirable that the direction identification unit 10 be eliminated after assembling, but it is not necessary to completely eliminate the direction identification unit 10 outside the effective area. It should be noted that the light is erased by, for example, irradiating the direction identification unit 10 with ultraviolet light, infrared light, a laser used for an optical disk, or the like using external energy.
[0048]
Further, the mark of the direction identification unit 10 may be any mark such as a mark having a protrusion, a mark having a concave portion, a mark having coloring, a mark having a different reflectance, or the like.
According to the above-described embodiment, the optical characteristics of the objective lens alone are aligned in one direction, and the direction identification unit is provided on the objective lens so as to stabilize the characteristic variation due to the rotational arrangement of the objective lens. Can be canceled, and the astigmatism characteristics of the optical pickup with reduced variation and stable can be obtained.
[0049]
The present invention is not limited to the above-described embodiment, and can be variously modified in an implementation stage without departing from the scope of the invention. For example, other than the objective lens, an optical component that is attached to the housing with an arrangement and an arrangement angle may be used.
[0050]
【The invention's effect】
As described above, in the optical pickup device, by providing the direction identification unit for the single performance of the optical component, the direction control of the optical characteristics at the time of assembly can be performed.
In addition, by marking the direction identification portion and then erasing it, an optical pickup device having stable optical performance can be generated.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of an optical pickup device according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of an optical disk device using an optical pickup device.
FIG. 3 is a diagram showing an objective lens according to the present invention.
FIG. 4 is a view showing the irradiation state of the laser beam at that time when the X point and the Y point of the objective lens in FIG. 3 are respectively set to the Z point of the holder.
FIG. 5 is a configuration diagram showing a first integrated optical unit.
[Explanation of symbols]
10 Direction identification unit 11 Edge 12 Holder 13 Openings 20, 21 Photodetector 101 Housing 201 First integrated optical unit 202 Second integrated optical unit 302 Dichroic PBS
303 Collimator lens 306 Reflecting mirror 307 Objective lens 400 Optical disk

Claims (13)

A transmitting and reflecting surface for transmitting or reflecting the laser light emitted from the light source unit for emitting the laser light,
An optical component, characterized in that a mark is formed at a peripheral position of the transmission / reflection surface where the aberration of the laser light transmitted or reflected by the transmission / reflection surface is minimized. The optical component according to claim 1, wherein the mark is formed in a convex shape or a concave shape. The optical component according to claim 1, wherein the mark is colored. The optical component according to claim 1, wherein the mark has a different reflectance from other portions. The optical component according to claim 1, wherein the mark is provided outside an effective area of the laser beam. The optical component according to claim 1, wherein the mark has a trace that disappears completely or is slightly left when heat is applied. A housing,
At least one or more light source units attached to the housing and for irradiating the information recording surface of the disk with laser light;
A transmission / reflection surface attached to the housing for transmitting or reflecting the laser light emitted from the light source unit, wherein the transmission / reflection that minimizes aberration of the laser light transmitted or reflected through the transmission / reflection surface; An optical component having a mark formed at a peripheral position of the surface. The optical pickup device according to claim 7, wherein the mark is formed in a convex shape or a concave shape. The optical pickup device according to claim 7, wherein the mark is colored. The optical pickup device according to claim 7, wherein the mark has a different reflectance from other portions. The optical pickup device according to claim 7, wherein the mark is provided outside an effective area of the laser beam. The optical pickup device according to claim 7, wherein the mark has a trace that disappears completely or is slightly left when heat is applied. A housing,
At least one or more light source units attached to the housing and for irradiating the information recording surface of the disk with laser light;
A transmission / reflection surface attached to the housing for transmitting or reflecting the laser light emitted from the light source unit, wherein the transmission / reflection that minimizes aberration of the laser light transmitted or reflected through the transmission / reflection surface; An optical component having a mark formed at a peripheral position of the surface,
A turntable for mounting the disk,
An optical disk device, comprising: a disk motor configured to rotationally drive the disk mounted on the turntable.

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