JPH10162411A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the optical pickup device at low cost to be capable of irradiating an optical disk in different substrate thickness with light beams from different light sources respectively and surely receiving light of a regenerative signal. SOLUTION: Light emitting/receiving units 1 and 2 having light emitting points 1a and 2a for emitting different light beams A and B in wavelength and light receiving elements respectively are used. These light emitting/receiving units 1 and 2 are so arranged that an optical distance (b) between the light emitting/receiving unit 2 for emitting the light beam B of a long wavelength and a polarizing beam splitter 3 is shorter than an optical distance (a) between the light emitting/receiving unit 1 and the polarizing beam splitter 3.

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 for recording / reproducing or erasing an information recording medium, and more particularly to an optical pickup device which can be used in a plurality of types of information recording media having different specifications and standards. is there.

[0002]

2. Description of the Related Art Technologies for irradiating an optical disk with a light beam and detecting reflected light to reproduce information recorded on a recording surface of the optical disk include CD (Compact Disk),
It is widely used as a D (laser disk) device or the like. In an optical disc apparatus for reproducing such an optical disc, a light beam emitted from a light source such as a semiconductor laser is focused on a recording surface of the optical disc by an objective lens.
The information signal recorded on the optical disk is reproduced by detecting the reflected light from the optical disk by the photodetector.

However, in recent years, there has been a demand for higher-quality information, for example, higher resolution in video images, and the amount of information to be handled is steadily increasing. In order to cope with this, recording densities of optical discs have been increased. For example, a new optical disc standard such as a DVD (digital video disc) has been newly proposed and has just been realized. It is getting. For example, C
Comparing the size of the pit, which is a unit in which information is recorded, between D and DVD, the minimum length of the pit was about 0.83 μm for CD but 0.4 μm for DVD.
And the pitch between tracks on which information is recorded is from 1.64 μm for CD to 0.74 μm for DVD.
m.

In order to increase the recording density of an optical disk as described above, not only the size of a pit is reduced, but also the size (spot diameter) of an optical spot for reading the minute pit is reduced. There is a need. The spot diameter is given by the following equation, where λ is the wavelength of the light beam to be used, and NA is the numerical aperture of the objective lens. Spot diameter = k × λ / NA (k is a constant) From the above equation, when trying to read a higher density optical disc, use a light beam with a shorter wavelength λ or use a lens with a larger numerical aperture NA. It turns out that it is necessary.

However, a general optical head has a configuration having one objective lens and one laser.
A conventional optical disk cannot be read by an optical head having an optical system compatible with a high-density optical disk, that is, an optical system capable of forming a smaller spot diameter than a conventional optical disk.

On the other hand, when an optical head for a high-density optical disk uses an objective lens having a large NA, spot disturbance due to the tilt of the optical disk with respect to the optical system becomes large. For example, the thickness of the DVD substrate is set to 0.6 mm, which is １ ／ of the thickness of the CD substrate, because the disturbance is reduced. As a result, aberration occurs due to the difference in substrate thickness.

In order to use optical disks having different spot diameters and substrate thicknesses, for example, an optical disk device having two objective lenses is disclosed in Japanese Patent Application Laid-Open Nos.
It is disclosed in Japanese Patent Publication No. 4-289530. Also, JP-A-6-2598
No. 04 discloses that a light beam from a semiconductor laser for a CD and a semiconductor laser for a thin optical disk is condensed on an optical disk by using a half mirror so that the light beams have substantially the same path, and the reflected light is passed through a wavelength selection mirror. There is disclosed an optical pickup device in which the light is again separated into two light beams by passing through, and each of the light detectors receives the light.

[0008]

However, when a plurality of optical heads are provided as in the apparatus disclosed in Japanese Patent Application Laid-Open Nos. 4-28232 and 4-289530, at least two optical heads are required. In addition to this, there are problems that the cost increases, the weight increases, the inertia of the optical pickup device increases, and the increase in space makes downsizing difficult.

The apparatus disclosed in Japanese Patent Application Laid-Open No. 6-259804 has a complicated structure, requires adjustment of each light receiving element corresponding to each light source, increases the number of parts, and leads to an increase in cost. . In addition, since there are a plurality of optical separation systems, not only the energy loss of the light beam is large, but also there are many error factors. Therefore, the reliability is liable to be lost due to an adjustment error, an aging after the adjustment, and the like. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to read information from an optical disk having a different substrate thickness by using a single objective lens. Another object of the present invention is to provide an optical pickup device which is low-cost and easy to miniaturize.

[0011]

In order to solve the above-mentioned problems, an optical pickup device according to the first aspect of the present invention has a light-collecting means for condensing a light beam on a recording layer of an optical disk. , A plurality of light-emitting and light-receiving units each having a light source that emits a light beam, and a photodetector that receives a light beam that coincides with the optical axis of the light beam to be emitted, and transmitting or transmitting a light beam from each light-emitting and light-receiving unit. An optical system for guiding the light beam reflected by the recording layer to the respective light emitting and receiving units while reflecting the light beams to the respective light emitting and receiving units, wherein the plurality of light emitting and receiving units emit light beams having different wavelengths from each other. And
The light emitting and receiving unit that emits a light beam with a longer wavelength,
The optical system is characterized in that the optical distance between a light source incorporated in each light emitting and receiving unit and the optical system is shortened.

With the above arrangement, the light beams emitted from the respective light emitting and receiving units are guided to the light condensing means via the optical system, irradiated to the recording layer of the optical disk, reflected, and pass through substantially the same path. To return to the light emitting and receiving unit. At this time, since the optical distance between the light source and the optical system is different for each light emitting and receiving unit, the radiation angle (beam width) of the light beam provided to the light condensing means is different. As a result, the focal position changes in the optical axis direction depending on each light beam. In this case, the shorter the optical distance, the farther the focal position is. The optical distance is set such that the longer the wavelength of the light beam, the shorter the optical distance, that is, the longer the focal position. Since a light beam having a longer wavelength has a lower refractive index, the focal position is further distant. This makes it possible to set the focal position of each light beam so as to form an appropriate spot diameter for optical disks having different substrate thicknesses. Moreover, since the light emitting and receiving unit incorporating the light source and the photodetector is used so that the optical axis of the emitted light beam and the reflected light to be received coincide with each other, the configuration of the optical system is simplified, and It is possible to reduce the size and cost.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, in addition to the configuration of the first aspect, an optical path length correction provided in an optical path of a light beam incident on the optical system is provided. The optical distance is varied by means. With the above configuration, even when the difference in the optical distance of the plurality of light emitting and receiving units with respect to the optical system cannot be physically realized due to restrictions on the size and layout of the optical pickup device, the light path length correcting means can be used for each light emitting and receiving unit. An appropriate optical distance difference can be provided. That is, it is possible to design an optical pickup device in consideration of space efficiency and the like while giving an optimum optical distance difference.

According to a third aspect of the present invention, there is provided an optical pickup device having a light condensing means for condensing a light beam on a recording layer of an optical disk. A plurality of light-emitting and light-receiving units each having a light source that emits light, and a light detector that receives a light beam that coincides with the optical axis of the light beam that is emitted; and the light-collecting unit that transmits or reflects light beams from each light-emitting and light-receiving unit. An optical system for guiding reflected light of the light beam by the recording layer to the respective light emitting and receiving units, wherein the plurality of light emitting and receiving units emit light beams having different wavelengths from each other, and The means has at least the same number of different irradiation areas as the light emitting and receiving units, and each irradiation area is at least emitted by each light emitting and receiving unit. It is characterized in that the light beam is formed such that condensed on the recording surface of the corresponding optical disc, respectively that.

According to the above arrangement, the light beams emitted from the respective light emitting and receiving units are guided to the light condensing means via the optical system, irradiated to the recording layer of the optical disk, reflected, and pass through substantially the same path. To return to the light emitting and receiving unit. At this time, the light beam emitted from each of the light-emitting and light-receiving units can form different focal positions and different converging spots with respect to the condensing means depending on different irradiation areas. As a result, optical discs having different standards, such as a difference in aberration due to a difference in base material thickness and a difference in diameter of a condensed spot formed on the recording surface, are condensed on the respective recording surfaces according to the respective standards. It becomes possible. Moreover, since the light emitting and receiving unit incorporating the light source and the photodetector is used so that the optical axis of the emitted light beam and the reflected light to be received coincide with each other, the configuration of the optical system is simplified, and It is possible to reduce the size and cost.

According to a fourth aspect of the present invention, in order to solve the above-mentioned problem, in addition to the configuration of the first or third aspect, each of the light emitting and receiving units emits light beams having different polarization directions from each other. A polarization filter that emits light and selectively transmits or reflects according to the polarization direction of the light beam is provided as the optical system.

With the above arrangement, the light beam emitted from a certain light emitting / receiving unit passes through the optical system provided with the polarizing filter, further passes through the condensing means, is reflected on the recording surface of the optical disk, and is again transmitted. The polarization direction of the optical system is set so as to return to the light emitting and receiving unit via the optical system. In this case, reflected light reflected by a light beam emitted from a different light emitting and receiving unit has a different polarization direction. Therefore, the light is reflected by the polarizing filter in the optical system. That is, the reflected light by the light beam emitted from the different light emitting and receiving units is not received. In addition, since different optical disks can be used for each light beam as described above, it is possible to reliably select the reflected light from the target optical disk.

According to a fifth aspect of the present invention, in order to solve the above-mentioned problems, in addition to the configuration of the first or third aspect, the optical system is selected as the optical system according to the wavelength of the light beam. A wavelength filter for transmitting or reflecting light is provided.

According to the above configuration, the light beams emitted from the respective light emitting and receiving units are originally set to different wavelengths. Therefore, a wavelength filter that transmits or reflects only one of the wavelengths is used. The light beam can be separated in the same manner as described above, and the target reflected light from the optical disk can be reliably selected. Moreover, in the case of the present invention, the light emitting and receiving unit can be installed without depending on the polarization direction of the light beam. That is, accuracy factors can be improved because the error factors in manufacturing can be reduced.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

[Embodiment 1] FIG. 1 shows an embodiment of the present invention.
The following is a description based on FIG. As shown in FIG. 1, the optical pickup device according to the present embodiment is provided with light emitting and receiving units 1 and 2 that emit light beams having different wavelengths. The light beams A and B emitted from the respective light emitting and receiving units 1 and 2 are shorter in wavelength than the light beam A. Further, a polarizing beam splitter 3 for guiding the light beams A and B to a condensing unit described later is provided as an optical system, and a collimating lens 4 and an objective lens 5 are provided as a condensing unit for the light beam. Further, an aberration compensating element 6 as an optical path length correcting means is provided in the optical path of the light beam emitted from the light emitting / receiving unit 2.
Specifically, it is provided between the light emitting and receiving unit 2 and the polarizing beam splitter 3. Further, an opening for limiting the range of the light beam applied to the objective lens 5 is provided as an opening 7 just before the objective lens 5 for the light beam A, and just before the polarization beam splitter 3 for the light beam B. An opening 8 is provided.

Although not shown, the light emitting and receiving units 1 and 2 each include a light source for emitting a light beam and a photodetector for detecting reflected light, and further include an optical axis of the emitted light beam,
The hologram element is arranged such that the optical axis of the reflected light that can be received coincides with the hologram element. However, the light emitting and receiving units 1 and 2 are arranged so that the polarization directions of the light beams when passing through the optical system are orthogonal to each other.

The polarizing beam splitter 3 is coated with a polarizing film 3a (polarizing filter) that transmits or reflects according to the polarization direction. Here, the light beam A from the light emitting / receiving unit 1 is transmitted, and the light emitting / receiving unit is used. The polarization direction is set so as to reflect the light beam B from the light source 2. The physical distances a and b between the polarization beam splitter 3 and the light emitting points 1a and 2a in each of the light emitting and receiving units 1.2 are made equal.

The light condensing means, that is, the collimating lens 4 and the objective lens 5, cause each light beam to be condensed on the recording surface of the optical disk and the reflected light is condensed on the photodetector. .

The aberration compensating element 6 is provided for correcting a shift of the focal position in the optical axis direction, which is called a spherical aberration. B radiation angle (hereinafter referred to as beam width)
Is expanding. As a result, the beam width of the light beam incident on the objective lens 5 is widened and the focal position is far. Note that changing the beam width of the light beam B so as to increase it corresponds to shortening the optical distance with respect to the physical distance b between the light emitting / receiving unit 2 and the polarizing beam splitter 3.

The operation of the optical pickup device in the above configuration will be described. First, the light beam A emitted from the light emitting / receiving unit 1 reaches the polarization beam splitter 3. At this time, since the polarization direction of the light beam A coincides with the polarization direction of the polarizing film 3a, the light beam A passes through the light beam splitter 3 and passes through the opening 7 between the collimating lens 4 and the light beam A.
The light is focused on the recording layer on the optical disk 9 by the objective lens 5. In the above, the light beam A passing between the collimator lens 4 and the objective lens 5 is substantially parallel light. Similarly, the light A ′ reflected by the optical disk 9 (passing through the same optical path as the light beam A) reaches the polarization beam splitter 3 via the opening 7, the objective lens 5 and the collimator lens 4. At this time, the polarization direction of the reflected light A 'is also substantially the same, so that the polarization beam splitter 3
And the reflected light A ′ is guided to the photodetector of the light emitting and receiving unit 1.

On the other hand, the light beam B emitted from the light emitting / receiving unit 2 passes through the aberration compensating element 6 and the opening 8
The polarization beam splitter 3 is reached. At this time, since the polarization direction of the light beam is orthogonal to the polarization direction of the polarizing film 3a, the light beam B is reflected by the polarizing film 3a and collected by the collimator lens 4 and the objective lens 5. Here, since the light beam B has a longer wavelength and a lower refractive index than the light beam A from the light emitting and receiving unit 1, the light beam B has a lower refractive index than the light beam A emitted from the light emitting and receiving unit 1. The focal position becomes farther in the optical axis direction. Further, the physical distance b
Since the optical distance with respect to (= a) is short, the beam width between the collimator lens 4 and the objective lens 5 is slightly wider than the parallel light (FIG. 2). Therefore, the focal position further increases in the optical axis direction.

As a result, it is possible to correct the focal position for the optical disk 10 having a greater thickness than the light emitting and receiving unit 1. Then, light B ′ reflected by the optical disk 10
(Which passes through substantially the same optical path as the light beam B)
Then, the light reaches the polarizing beam splitter 3 via the collimating lens 4. At this time, the direction of polarization of the reflected light B 'is also substantially orthogonal to the direction of polarization of the polarizing film 3a.
And the reflected light B ′ is guided to the photodetector of the light emitting and receiving unit 2. Although the aberration compensating element 6 may be provided in the optical path of the light beam A, in this case, it is preferable to make the wavelength of the light beam A shorter than that of the light beam B. Otherwise, the shift direction of the spherical aberration due to the aberration compensating element 6 and the shift direction of the spherical aberration due to the length of the wavelength are reversed.

As described above, the light-emitting and light-receiving units 1 and 2 aim at reading optical disks 9 and 10 having different thicknesses from each other, and are controlled by the aberration compensation element 6 provided in the optical path on the light-emitting and light-receiving unit 2 side. The beam width of the light beam B is slightly widened, and the focal position is shifted so as to be farther in the optical axis direction by the objective lens 5. That is, since the spherical aberration can be largely corrected for the same condensing unit, the recording surface of the thin optical disk 9 can be read by the light beam A from the light emitting and receiving unit 1, and The light beam B from the light emitting and receiving unit 2 allows the recording surface of the thick optical disk 10 to be read.

In addition to the difference in thickness, for example,
The above configuration can be applied to the case where an optical disk having two recording surfaces with different depths, each having a recording surface formed at the position of the recording surface of the optical disk 9 and the optical disk 10, is used.

Although the opening 8 is provided immediately after the light emitting and receiving unit 2 in the above embodiment, FIGS.
As shown in FIG. 7, instead of the opening 8, a polarizing film 21 having the same polarization direction as the polarizing film 3a in the polarizing beam splitter 3 may be formed.

In this case, the light beam B whose beam width is slightly wider than that of the parallel light between the collimator lens 4 and the objective lens 5 by the aberration compensating element 6 is, as shown in FIG. 5 is slightly larger than that in FIG. However, even if the light beam B is incident on the polarizing film 21 whose polarization direction is set in a direction orthogonal to the polarization direction of the light beam B, the light beam B is reflected or absorbed. The diameter of B is the same as when the opening 8 is provided. Conversely, the polarization direction of the light beam A matches the polarization direction of the polarizing film 21, and the light beam A passes through the polarizing film 21 without any problem.
The configuration for condensing the light beam A on the optical disk 9 is equivalent to the configuration in FIG. The polarizing film 21
As shown in FIGS. 4 (a) and 4 (b), is formed on the surface of the objective lens 5 in a state of being coated in a concentric band shape.
The size can be reduced.

In the above description, the aberration compensating element 6 is used as the optical path length correcting means. However, as shown in FIG. 5, a flat glass 11 may be used. In the case of the flat glass 11, the refraction of the light beam B on the flat glass 11 causes the light emitting and receiving unit 2 to emit light similarly to the aberration compensation element 6.
The optical distance from the light emitting point 2a to the collimating lens 4 can be shorter than the physical distance b. as a result,
The light beam from the light emitting and receiving unit 2 is in a state where the beam width between the collimating lens 4 and the objective lens 5 is slightly wider than parallel. Therefore, similarly, the focal position can be made farther in the optical axis direction. As a result, it is possible to correct spherical aberration for optical disks having different thicknesses. For example, assuming that the configuration other than the aberration compensating element 6 is the same as that of FIG. 2, the thickness and the refractive index of the flat glass 11 are determined by the beam width of the light beam B between the collimator lens 4 and the objective lens 5. It may be appropriately adjusted so as to be equal to 1 or the case of FIG.

As shown in FIG. 6, the physical distance a between the polarizing beam splitter 3 and each of the light emitting / receiving units 1 and 2
-It goes without saying that the same effect can be obtained even if they are arranged so that b is different.

Further, in the above-described embodiment, in order to separate the reflected light to the light emitting and receiving units 1 and 2, the polarization directions of the light beams emitted from the light emitting and receiving units 1 and 2 are made orthogonal to each other, and the polarization beam splitter 3 is used. However, it is also possible to use a half mirror instead of the polarization beam splitter 3.
In this case, it is not necessary to make the polarization directions of the light beams of the light emitting and receiving units 1 and 2 orthogonal to each other.
When the above polarizing film 21 is applied, the polarization directions of the light beams of the light emitting and receiving units 1 and 2 must be orthogonalized. In addition, it is necessary to note that a large amount of light is lost in each of the light beam and the reflected light when passing through the half mirror.

Further, a wavelength selection mirror may be used as the optical system. The wavelength selection mirror is a polarizing beam splitter 3
Is replaced by a wavelength selection film (wavelength filter). At this time, it is necessary to replace the polarization film 21 of the objective lens 5 with a wavelength selection film having the same characteristics. The wavelength selection film transmits only light of a specific wavelength or conversely reflects only light of a specific wavelength. For example, in the configuration of FIG. By using a wavelength selection film having such a property as to transmit the above wavelength and reflect the wavelength of the light beam B from the light emitting / receiving unit 2, the same effect as described above can be obtained.

Embodiment 2 Another embodiment of the present invention will be described below with reference to FIGS. 7 and 8. For the sake of convenience, the same reference numerals are given to components having the same functions as those shown in the drawings of the first embodiment, and the description thereof will be omitted.

In the first embodiment, the objective lens 5 formed with the same curvature and the light emitting / receiving units 1 and 2 for emitting two light beams having different wavelengths are provided, and the optical path length is corrected by the optical path length correcting means. Thus, the same optical pickup device enables recording and reproduction of optical disks having different thicknesses. Then, as shown in FIG. 7, the optical pickup device according to the present embodiment also emits light beams having different wavelengths and emits and receives light and light receiving units 1 and 2 having polarization directions different from each other in optical diameter, and a polarization beam splitter. 3, a collimating lens 4, and an objective lens 5 'are provided. Further, an opening for limiting the range of the light beam A given to the objective lens 5' is opened immediately before the objective lens 5 for the light emitting and receiving unit 1. 7 is the same.

However, in the present embodiment, instead of using the optical path length correcting means, as shown in FIGS.
The lens surface of the objective lens 5 'is a concentric partial lens 5
The division into a 'and 5b' causes a change in the focal position. That is, the area of the partial lens 5a 'is set so that the light beam A of the light emitting and receiving unit 1 is focused on the recording surface of the thin optical disk 9, and
In the area b ', the curvature and angle of each partial lens are set so that the light beam B of the light emitting / receiving unit 2 is focused on the recording surface of the thick optical disk 10. Also, the partial lens 5
In the region a ', a polarizing film 22 having a polarization direction different from the polarization direction of the light beam B is formed.

Therefore, in the above configuration, when the light beam A is emitted from the light emitting / receiving unit 1, the light beam A transmitted through the polarizing film 3a of the polarizing beam splitter 3 is used.
Reaches the objective lens 5 ′ through the collimating lens 4 and the opening 7. Here, the light beam A passes through the entire area of the objective lens 5 'and is condensed by the partial lenses 5a' and 5b 'at the positions of the recording surfaces of the optical disks 9 and 10, respectively. Since the focal position is set to, recording or reproduction can be performed only on the recording surface of the optical disc 9.

The light beam B from the light emitting / receiving unit 2
Is emitted, the light beam B reflected on the polarizing film 3a of the polarizing beam splitter 3 reaches the objective lens 5 via the collimating lens 4. Here, the light beam B passes only through the region of the partial lens 5b 'where the polarizing film 21 of the objective lens 5' is not formed.
And recording or reproduction becomes possible.

In this embodiment, similar to the above embodiment, the same effect can be obtained by replacing the polarizing films 3a and 22 with wavelength selecting films having the same characteristics.

In each of the above embodiments,
Although the light beams emitted from the light emitting and receiving units 1 and 2 have different wavelengths, light beams having the same wavelength can theoretically be used except when a wavelength selection film is used.

However, when recording / reproducing an optical disk having two recording surfaces having different depths using the light beam having the same wavelength, when a light beam is applied to a recording surface having one depth, There is a high possibility that the reflected light reflected by another recording surface will adversely affect the reproduction / recording signal. Therefore, utilizing the fact that the refractive index for the same substrate differs depending on the wavelength of the light beam, the amount of change in the focal position due to the difference in disk thickness and the difference in wavelength is added. For example, the partial lens 5b 'of the objective lens 5'
In this case, even when the light beam A forms a spot at the position on the recording surface of the optical disk 10, the possibility of being read as a signal is low because the spot diameter and the like are not appropriate. That is, the influence of another recording surface or the influence on another recording surface can be reduced.

[0044]

As described above, the optical pickup device according to the first aspect of the present invention includes a light source that emits a light beam and a photodetector that receives a light beam that coincides with the optical axis of the emitted light beam. A plurality of light-emitting and light-receiving units each having an optical system for transmitting or reflecting a light beam from each light-emitting and light-receiving unit and guiding the light beam to the condensing unit, and guiding reflected light of the light beam by the recording layer to each light-emitting and light-receiving unit Wherein the plurality of light emitting and receiving units emit light beams having different wavelengths from each other, and are arranged such that the light sources incorporated in each light emitting and receiving unit have different optical distances from the optical system. Configuration.

Therefore, the light beams emitted from the respective light emitting and receiving units have different beam widths when given to the light condensing means, and the focal position changes in the optical axis direction depending on the light beams. Also, the longer the wavelength of the light beam, the focal position is set to an optical distance farther,
Further, the difference between the focal positions is promoted. As a result, it is possible to form an appropriate spot diameter for optical disks having different substrate thicknesses. Moreover,
Since the light emitting and receiving unit incorporating the light source and the photodetector is used so that the optical axis of the emitted light beam coincides with the optical axis of the reflected light to be received, the configuration of the optical system is simplified and the size of the optical pickup device is reduced. In addition, there is an effect that the cost can be reduced.

According to a second aspect of the present invention, as described above, in addition to the configuration of the first aspect, the optical pickup is provided by an optical path length correcting means provided in the optical path of the light beam incident on the optical system. The target distance is different.

Therefore, in addition to the effect of the configuration of the first aspect, the optical path length correction means gives an appropriate difference in the optical distance for each light emitting and receiving unit regardless of the size and layout restrictions of the optical pickup device. Therefore, it is possible to design an optical pickup device in consideration of space efficiency and the like while giving an optimum optical distance difference.

As described above, the optical pickup device according to the third aspect of the present invention includes the light sources for emitting the light beams and the photodetectors for receiving the light beams coincident with the optical axes of the emitted light beams. A plurality of light-emitting and light-receiving units, and an optical system that transmits or reflects the light beam from each light-emitting and light-receiving unit and guides the light beam to the condensing unit, and guides the light beam reflected by the recording layer to each light-emitting and light-receiving unit. The plurality of light emitting and receiving units emit light beams of different wavelengths from each other, while the condensing means has at least the same number of different irradiation areas as the light emitting and receiving units, and each of the irradiation areas is at least The light beam emitted from each light emitting and receiving unit is formed so as to be focused on the recording surface of the corresponding optical disc.

Therefore, when the light beams emitted from the respective light emitting and receiving units irradiate a plurality of irradiation areas of the light condensing means, for example, the focal position, the diameter of the condensed spot, etc. The light beams can be focused differently. That is, with respect to a plurality of types of optical discs having different standards, it is possible to form condensed spots having different aberrations, focal positions, diameters of condensed spots and the like and conforming to the respective standards on the respective recording surfaces. Moreover, since the light emitting and receiving unit incorporating the light source and the photodetector is used so that the optical axis of the emitted light beam and the reflected light to be received coincide with each other, the configuration of the optical system is simplified, and This has the effect of enabling downsizing and cost reduction.

As described above, the optical pickup device according to the fourth aspect of the present invention, in addition to the configuration of the first or third aspect,
Each of the light emitting and receiving units emits a light beam having a different polarization direction, and a polarization filter that selectively transmits or reflects the light beam according to the polarization direction of the light beam is provided as the optical system.

Therefore, in addition to the effect of the first or third aspect, the light beam emitted from a certain light emitting / receiving unit passes through the optical system provided with the polarizing filter.
The reflected light reflected by the light beams emitted from the different light emitting and receiving units has different polarization directions, and is reflected by the polarizing filter in the optical system. That is, there is an effect that the light beams can be surely separated without receiving the reflected light by the light beams emitted from the different light emitting and receiving units.

As described above, the optical pickup device according to the fifth aspect of the present invention, in addition to the configuration of the first or third aspect,
The optical system has a configuration in which a wavelength filter that selectively transmits or reflects according to the wavelength of the light beam is provided.

Therefore, in addition to the effect of the structure of claim 1 or 3, the fact that the wavelength of the light beam is different makes it possible to reliably separate the light beam by the wavelength filter as in the case of claim 4. It is possible to select the reflected light from the optical disk. In addition, in the case of the present invention, since it does not depend on the polarization direction of the light beam, there is an effect that the error factor in manufacturing can be reduced.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of an objective lens and an optical disk irradiation site in FIG. 1;

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

4 (a) is an enlarged view of an objective lens and an optical disk irradiation site in FIG. 3, and FIG. 4 (b) is a plan view of the objective lens viewed from the direction of arrow X in FIG. 4 (a). It is.

FIG. 5 is a schematic configuration diagram showing a configuration of an optical pickup device according to still another embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a configuration of an optical pickup device according to still another embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a configuration of an optical pickup device according to still another embodiment of the present invention.

8 (a) is an enlarged view of an objective lens and an optical disk irradiation site in FIG. 7, and FIG. 8 (b) is a plan view of the objective lens viewed from the arrow X direction in FIG. 7 (a). It is.

[Explanation of symbols]

 Reference Signs List 1 light emitting / receiving unit 2 light emitting / receiving unit 3 polarizing beam splitter (optical system) 3a polarizing film (polarizing filter) 4 collimating lens (light collecting means) 5 objective lens (light collecting means) 5 'objective lens (light collecting means) 5a' Partial lens (light collecting means / irradiation area) 5b 'Partial lens (light collecting means / irradiation area) 6 Aberration compensating element (optical path length correcting means) 9 Optical disk 10 Optical disk 11 Flat glass (optical path length correcting means)

Claims (5)

[Claims] 1. An optical pickup device having a light condensing means for converging a light beam on a recording layer of an optical disk, comprising: a light source that emits a light beam; and a light beam that coincides with an optical axis of the emitted light beam. A plurality of light-emitting and light-receiving units each having a photodetector that transmits and reflects light beams from each of the light-emitting and light-receiving units to guide the light to the light condensing unit, and to reflect the light beams reflected by the recording layer into respective light-emitting and light-receiving units. An optical system that guides the light emitting and receiving unit, wherein the plurality of light emitting and receiving units emit light beams of different wavelengths, and the light emitting and receiving unit that emits a light beam with a longer wavelength, the light source built in each light emitting and receiving unit An optical pickup device, wherein an optical distance between the optical pickup and the optical system is shortened. 2. An optical pickup device according to claim 1, wherein said optical distance is made different by an optical path length correcting means provided in an optical path of a light beam incident on said optical system. 3. An optical pickup device having a light condensing means for condensing a light beam on a recording layer of an optical disk, wherein the light pickup emits a light beam and receives a light beam coincident with the optical axis of the emitted light beam. A plurality of light-emitting and light-receiving units each having a photodetector that transmits and reflects light beams from each of the light-emitting and light-receiving units to guide the light to the light condensing unit, and to reflect the light beams reflected by the recording layer into respective light-emitting and light-receiving units. An optical system for guiding the unit, the plurality of light-emitting and light-receiving units emit light beams of different wavelengths from each other, and the light-collecting means has at least the same number of different irradiation areas as the light-emitting and light-receiving units, Each of the irradiation areas is formed so that at least a light beam emitted from each of the light-emitting and light-receiving units is focused on the recording surface of the corresponding optical disc. The optical pickup apparatus characterized by being. 4. Each of the light-emitting and light-receiving units emits a light beam having a polarization direction different from each other, and a polarization filter for selectively transmitting or reflecting the light beam according to the polarization direction of the light beam is provided as the optical system. The optical pickup device according to claim 1, wherein the optical pickup device is provided. 5. The optical pickup device according to claim 1, wherein a wavelength filter that selectively transmits or reflects according to the wavelength of the light beam is provided as the optical system.