JP2002304761A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device constituted in such a manner that all of the luminous fluxes from plural light sources varying in wavelengths are made incident perpendicularly on an objective lens and a costly and small- sized wavelength selection prism having a difficulty in processing is not needed. SOLUTION: This optical pickup device has the plural light sources 1 and 2 consisting of semiconductor laser and varying in the wavelengths and writes and erases and/or reproduces information to and/or from an optical recording medium 7 while irradiating the recording surface on the optical recording medium across optical means for guiding the luminous fluxes from the plural light sources 1 and 2 to the optical recording medium and receiving the return luminous fluxes reflected by the recording surface by a photodetector 9. The optical means for guiding the luminous fluxes from the plural light sources 1 and 2 to the optical recording medium is an optical element 5 having a total reflection film 5-b and a wavelength selection film 5-a and is not integrated with the plural light sources 1 and 2 housed in one package.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical pickup device, and more particularly, to a digital versatile disk (DV).
The present invention relates to an optical pickup device capable of recording or reproducing a plurality of types of optical recording media such as D) media and compact disc (CD) media.

[0002]

2. Description of the Related Art Conventionally, the following technologies are known as optical pickup devices capable of recording or reproducing data on or from a plurality of types of optical recording media. (1) “DVD / CD / CD-R COMPATIBLE PICK-UP WITH TWO-WAVEL
ENGTH TWO-BEAM LASER ”IEEE Transactions on Consume
r Electronics, Vol.44, No.3, AUGUST 1998. A 780 nm semiconductor laser (LD) for reproducing CD-based media and a 6-nm laser for reproducing DVD-based media.
A two-wavelength LD is made by disposing a 35 nm LD in close proximity,
Using a difference in polarization direction between two wavelengths, a Wollaston prism detects a signal with one light receiving element, thereby realizing a two-wavelength compatible optical pickup. However, in the above optical pickup, the cost is increased due to the use of a special LD whose light emitting point is shifted from the center of the chip, and the light incident on the objective lens is obliquely incident because the light emitting point interval remains 150 μm, so that the objective The tolerance for assembling the lens becomes small.

(2) “Module for recording / reproducing device”, JP-A-09-120568. With the above-described optical pickup, a hologram and a light receiving element are shared for two wavelengths, and LD chips of two wavelengths are arranged close to each other.
Pickup module for two wavelengths. However, in this pickup module,
Even if the LD chips are to be arranged close to each other, the size of the LD chip itself cannot be increased, and the distance cannot be increased to about 300 microns. In addition, although the optical axes are aligned using a prism using a wavelength selection film, it is difficult to manufacture a small prism that can be mounted on an LD-PD unit, and there is a disadvantage that the cost increases.

[0004]

In an optical pickup device having a plurality of light sources of different wavelengths, if the light emitting points are far apart, at least one of the light incident on the objective lens will be obliquely incident, and aberration will be reduced. Will occur.
Therefore, accurate recording and reproduction of information cannot be performed. The closer the light emitting point is to the utmost, the less the occurrence of aberration is. However, there is a limit to this, and the aberration does not become zero and the tilt margin of the objective lens becomes small. Therefore, as in the prior art (2), if light is combined by using a wavelength selective film prism to make the optical axes coincide with each other so that both light are perpendicularly incident on the objective lens, no aberration occurs. However, it is difficult to manufacture a small prism that can be mounted on an LD-PD unit, and there is a disadvantage that the cost is high.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and solves the above-mentioned problems of the prior art, in which light beams from a plurality of light sources having different wavelengths are vertically incident on an objective lens. It is another object of the present invention to provide an optical pickup device that does not require a small wavelength selection prism that is difficult and expensive to process. It is still another object of the present invention to provide an optical pickup device having a configuration capable of achieving downsizing and cost reduction in addition to the above objects.

[0006]

According to a first aspect of the present invention, there is provided an optical recording medium comprising: a plurality of light sources having different wavelengths each comprising a semiconductor laser; Irradiating a recording surface on an optical recording medium via an optical means for guiding the light, and writing / erasing / writing information while receiving a return light beam reflected by the recording surface by a light receiving element.
Or in an optical pickup device that performs reproduction, an optical unit that guides light beams from the plurality of light sources to an optical recording medium,
An optical element having a total reflection film and a wavelength selection film, which is not integrated with a plurality of light sources contained in one package. That is, in the optical pickup device according to claim 1, a two-wavelength light source unit including, for example, an LD with a wavelength of 780 nm and an LD with a wavelength of 635 nm or 650 nm as a plurality of light sources having different wavelengths composed of a semiconductor laser (LD). After the luminous flux from the two-wavelength light source unit is converted into substantially parallel light by a collimating lens, the optical axis directions are made coincident by using an optical element having a total reflection film and a wavelength selection film, and both lights are used. This is to form a good spot on the recording surface of the optical recording medium so that the light is incident perpendicularly on the objective lens.

According to a second aspect of the present invention, there are provided a plurality of light sources having different wavelengths composed of semiconductor lasers, and recording on an optical recording medium through an optical means for guiding light beams from the plurality of light sources to the optical recording medium. The optical pickup device irradiates the surface with light, reflects the return light beam reflected by the recording surface, diffracts the light beam by the diffractive element, receives the light beam by the light receiving element, and writes / erases / reproduces information. The optical means for guiding to the optical recording medium is an optical element having a total reflection film and a wavelength selection film, and is not integrated with a plurality of light sources or light receiving means. That is, claim 2
In the optical pickup device described above, as in the optical pickup according to the first aspect, as the plurality of light sources having different wavelengths composed of a semiconductor laser (LD), for example, an LD having a wavelength of 780 nm and an LD having a wavelength of 635 nm or 650 nm are used. After a light beam from the two-wavelength light source unit is turned into substantially parallel light by a collimating lens, both light beams are objective by using an optical element having a total reflection film and a wavelength selection film. A good spot is formed on the recording surface of the optical recording medium by allowing light to enter the lens perpendicularly. The light receiving element is also integrated with the two-wavelength light source unit and diffracted using a hologram. In this way, the size and cost can be reduced.

The invention according to claim 3 is the invention according to claim 1 or 2
In the optical pickup device described above, the optical element having the total reflection film and the wavelength selection film is arranged on the rising mirror unit. That is, in the optical pickup device according to the third aspect, in addition to the configuration and function according to the first or second aspect, an optical element having a total reflection film and a wavelength selection film is arranged at the position of the rising mirror to start up. The purpose of the present invention is to reduce the number of parts by also using the function of the mirror.

According to a fourth aspect of the present invention, in the optical pickup device according to the first, second or third aspect, the optical element having the total reflection film and the wavelength selection film has a beam shaping function in which a beam shaping magnification varies depending on the wavelength. It is characterized by having. That is, in the optical pickup device according to the fourth aspect,
In addition to the configuration and function of the first, second or third aspect, a beam shaping function is added to an optical element having a total reflection film and a wavelength selection film to enhance light use efficiency.

According to a fifth aspect of the present invention, in the optical pickup device according to the second, third or fourth aspect, the diffraction element comprises:
The hologram has a function of condensing light of each wavelength on substantially the same point of the light receiving element. That is, in the optical pickup device according to the fifth aspect, in addition to the configuration and function according to the second, third, or fourth aspect, the number of light receiving elements can be reduced by enabling light having different wavelengths to be received by the same light receiving element. It is intended to reduce the size without increasing the size and to simplify the circuit of the signal processing system.

According to a sixth aspect of the present invention, in the optical pickup device of the fifth aspect, there are provided two diffraction elements, and light having one wavelength is guided to the light receiving element by being subjected to diffraction twice, and the other. Is subjected to one diffraction action and guided to the light receiving element. That is, in the optical pickup device according to the sixth aspect, in addition to the configuration and the function according to the fifth aspect, it is possible to perform adjustment using two diffraction elements so that light having different wavelengths can be received by the same light receiving element. It is to be.

According to a seventh aspect of the present invention, in the optical pickup device according to any one of the first to sixth aspects,
Among the lights from the plurality of light sources having different wavelengths, a diffraction grating for dividing only light of one wavelength into three is arranged. That is, in the optical pickup device according to claim 7,
In addition to the configuration and function described in any one of claims 1 to 6, the CD system can perform tracking detection by a conventional three-beam method, and can continue to use a detection circuit such as an existing LSI. Is to do so.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on illustrated embodiments.

(Embodiment 1) FIG. 1 is a schematic structural view of an optical pickup device showing a first embodiment of the present invention.
Is a semiconductor laser (LD) having a wavelength of 635 nm or 650 nm for a DVD system, 2 is a semiconductor laser (LD) having a wavelength of 780 nm for a CD system, 3 is a beam splitter, 4 is a collimating lens, 5 is a total reflection film according to the present invention. , An optical element having a wavelength selection film, 6 an objective lens, 7 an optical recording medium such as a DVD optical disk or a CD optical disk, 8 a signal detection optical system, and 9 a light receiving element (PD).

In FIG. 1, the wavelength of the light source is 635 nm.
Alternatively, a 650 nm light beam emitted from a semiconductor laser (LD) 1 passes through a beam splitter 3, becomes parallel light by a collimator lens 4, is reflected by an optical element 5 according to the present invention, and is reflected by an objective lens 6 on an optical recording medium 7. The recording surface is irradiated. Here, the light reflected on the recording surface of the optical recording medium 7 returns to the original optical path, is reflected by the beam splitter 3, passes through the signal detection optical system 8, is received by the light receiving element 9, and is detected as a signal. On the other hand, light emitted from the semiconductor laser (LD) 2 having a wavelength of 780 nm similarly passes through the beam splitter 3, becomes parallel light by the collimating lens 4, is reflected by the optical element 5 according to the present invention, and is reflected by the objective lens 6. Irradiates the recording surface of the optical recording medium 7. Here, the light reflected on the recording surface of the optical recording medium 7 returns to the original optical path,
The light is reflected by the beam splitter 3, passes through the signal detection optical system 8, is received by the light receiving element 9, and is detected.

In such a configuration, the optical element 5 according to the present invention plays the following role. Wavelength 63
5 nm or 650 nm semiconductor laser 1 and wavelength 780
If the light emitting point interval of the semiconductor laser 2 of nm is large, the light emitted from the collimating lens 4 travels in an oblique direction as shown in FIG. This is a general 4 as shown in FIG.
When the light is reflected by the rising mirror 15 inclined by 5 °, a light beam inclined obliquely enters the objective lens 6. In order for the optical disk objective lens 6 to form a clear spot on the recording surface of the optical recording medium 7, the inclination of the incident light beam is ± 1 °.
It must be less than or equal. Assuming that the focal length of the collimating lens 4 is 10 mm, 10 × tan1 ° = 0.175 mm, and the light emitting point interval of the LD is 175 mm × 2 = 0.35 mm = 350 μm. Of course, this is the worst case with respect to the objective lens 6, so unless this interval is made smaller, it cannot be put to practical use.

Generally, the outer size of an LD chip is about 25.
Since it is 0 to 350 μm, the distance between the light emitting points is about 25 if two LD chips are bonded in a state where they are almost attached to each other.
It is 0 to 350 μm. Here, the light emitting point is shifted from the center of the outer shape of the LD chip to make the light emitting point interval 115 μm.
The conventional example is narrowed to m so that it can withstand practical use.
This is the configuration of (1). However, since the LD whose light emitting point is shifted from the center of the outer shape of the chip is special and expensive, the optical element 5 of the present invention shown in FIGS.

In FIG. 3, the wavelength is 635 nm or 65 nm.
A light beam of 0 nm from the semiconductor laser 1 is incident on the optical element 5 of the present invention at an angle of about 1 °. The incident light is the wavelength selection film 5
-a, and is reflected by the total reflection film 5-b toward the objective lens 6. At this time, if the total reflection film (total reflection surface) 5-b is tilted by 1 ° in order to correct the optical axis tilted by 1 °, light is incident on the objective lens 6 vertically and a good spot is obtained. Can be. On the other hand, the light beam from the semiconductor laser 2 having a wavelength of 780 nm is incident on the optical element 5 of the present invention while being inclined by about 1 ° in the opposite direction. The incident light is reflected by the wavelength selection film 5-a and travels to the objective lens 6. At this time, if the wavelength selection film 5-a is tilted by 1 ° opposite to the total reflection surface 5-b in order to correct the optical axis tilted by 1 °, light enters the objective lens 6 perpendicularly, and You can get a spot.

As described above, the wavelength selection film 5-a of the optical element 5
By tilting the and total reflection films 5-b at different angles in accordance with the respective incident angles, light of either wavelength can be made incident on the objective lens 6 perpendicularly, and a good spot can be obtained.

(Embodiment 2) Next, an embodiment which is an improvement of the conventional example using a prism to make the light emitting point closer will be described with reference to FIG. FIG. 4 is a schematic configuration diagram of an optical pickup device showing a second embodiment of the present invention, and components denoted by the same reference numerals as those in FIG. 1 are the same components. Also, in FIG.
Reference numeral 0 denotes a hologram, 11 denotes an LD-PD element in which semiconductor lasers (LDs) 1 and 2 of two wavelengths, which are light sources, and a light receiving element 9 are housed in one package. In the configuration of this embodiment, the semiconductor laser (LD) The light beam emitted from 1 or 2 passes through the hologram 10, becomes parallel light by the collimator lens 4, is reflected by the optical element 5 according to the present invention, and is irradiated on the recording surface of the optical recording medium 7 by the objective lens 6. . The light beam reflected by the recording surface of the optical recording medium 7 returns to the original optical path, is diffracted by the hologram 10, is received by the light receiving element 9, and is detected as a signal.

In order to reduce the size of the optical pickup device,
A method of using a hologram to house a light source (LD) and a light receiving element (PD) in one package is often used.
Even in such a case, when a plurality of light sources are used, it is still difficult to narrow the interval between the light emitting points. Therefore, there is a method in which a small prism for synthesizing light from a plurality of light sources is arranged in a package (LD-PD element) containing an LD and a PD, and light is emitted by aligning optical axes (conventional example).
(2)). As a result, the optical axes coincide with each other, so that there is no apparent interval between the light emitting points. However, a small prism is difficult to process and difficult to attach, and if there is an error during the attachment, the light beam will not be perpendicularly incident on the objective lens. Therefore, the optical element 5 of the present invention in FIG. 4 is such that the prism is separated from the LD-PD element and has the same size as a general optical component.

In FIG. 4, LDs 1 and 2 are general LDs simply arranged close to each other, as in the embodiment of FIG. In this case, a tilted light beam comes out of the collimating lens 4, but the tilt is corrected by the optical element 5 of the present invention as in the first embodiment. Spot can be obtained. According to such an embodiment, there is no need to use a small prism which is difficult to process and mount, and since it is arranged in the parallel optical path, astigmatism does not occur due to manufacturing errors and mounting errors.

(Embodiment 3) Although also shown in FIGS. 1 and 4,
By disposing the optical element 5 of the present invention having the wavelength selection film 5-a and the total reflection film 5-b at the position of the rising mirror below the objective lens 6, it can be used as an alternative to the rising mirror. it can. Although the function is the same even if it is not the position of the rising mirror, the rising mirror is present in addition to the optical element 5 of the present invention, and the number of components is increased.

(Embodiment 4) Next, another function of the optical element 5 of the present invention will be described. In the optical pickup device having the configuration shown in FIG. 1 or FIG. 4, the optical element 5 having the total reflection film and the wavelength selection film allows the objective lens 6 to emit light of either wavelength even if the light emitting points of a plurality of light sources are separated. A beam shaping function can be provided in addition to the function of allowing almost normal incidence. As shown in FIG. 5 (a), for example, the wavelength lambda ₁ of the light is reflected, the light of the wavelength lambda ₂ uses a wavelength selection film 5-a which transmits light of the wavelength lambda ₁ is not the beam shaping, wavelength light lambda ₂ will be beam shaping. Further, as shown in FIG. 5 (b), when providing the transmissive surface 5-c for transmitting light in front of the wavelength selection film 5-a, it can also be a beam shaping optical wavelengths lambda _1. In this case, the beams of both wavelengths can be shaped, but the shaping magnifications are different.

As described above, the optical element 5 according to the present invention can have a beam shaping function in which the shaping magnification varies depending on the wavelength. In addition, wavelength 635 nm or 650
Since the aspect ratio and the optimum beam shaping magnification are different between the LD having a wavelength of 780 nm and the LD having a wavelength of 780 nm, a beam shaping function having a different shaping magnification depending on the wavelength as in the present invention is useful.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described. Since the configuration is the same as that of the second embodiment shown in FIG. 4, the configuration will be described with reference to FIG. Wavelength 63 as the light source
A light beam emitted from the semiconductor laser 1 of 5 nm or 650 nm passes through the hologram 10, becomes parallel light by the collimating lens 4, is reflected by the optical element 5 of the present invention, and is recorded on the optical recording medium 7 by the objective lens 6. Irradiated on the surface. Here, the light reflected on the recording surface of the optical recording medium returns to the original optical path and enters the hologram 10. Then, for example, + 1st-order light of the diffracted light diffracted by the hologram 10 is received by the light receiving element 9 and signal detection is performed. On the other hand, light emitted from the semiconductor laser 2 having a wavelength of 780 nm similarly passes through the hologram 10, becomes parallel light by the collimating lens 4, is reflected by the optical element 5 of the present invention, and
The recording surface of the optical recording medium 7 is irradiated by the objective lens 6. The light reflected here returns to the original optical path, is diffracted by the hologram 10, is received by the light receiving element 9, and is detected as a signal.

In such a configuration, the hologram 10
FIG. 6 shows that chromatic aberration is large in a normal hologram.
As shown in (a), the wavelength λ ₁ (635 nm or 65
0 nm) and light having a wavelength λ ₂ (780 nm) have different focusing points. In this case, both lights can be detected by increasing the size of the light receiving element 9, but the focal point is about 300 μm.
Because of the above separation, the light receiving element becomes larger by that amount, which causes a problem that the light receiving element is easily affected by flare and the response speed is not sufficiently fast. In the present invention, since the light emitting points are far apart, light having a wavelength of 635 nm or 650 nm and light having a wavelength of 780 nm
Since the center of the light intensity distribution is shifted from the light of FIG.
A hologram cannot be shared by a method in which a signal is detected by splitting a beam with a light receiving element 9 having a light receiving surface divided into a plurality of parts, such as a push-pull (PP) method or a DPD method as shown in FIG. (Because offset occurs).

In order to cope with the above-mentioned problems, in this embodiment, as shown in FIG. 7B, the hologram 10 is divided into strips, each of which has a wavelength λ ₁ (635 nm or 650 nm). Wavelength λ ₂ (780 nm)
Light holograms are arranged alternately. By doing so, as shown in FIG. 7A, light of both wavelengths can be focused on substantially the same point of the light receiving element 9, and the area of the light receiving element 9 does not need to be increased. In addition, light of wavelength λ ₁ (635 nm or 650 nm) and wavelength λ ₂
(780 nm) can be corrected for the center deviation of the intensity distribution occurring between the light and the light of any wavelength. The two wavelengths are 635 nm or 650 nm for the DVD system and 7 wavelengths for the CD system.
Although 80 nm has been described as an example, a similar effect can be obtained by arranging holograms optimized for each wavelength even when recording / reproducing an optical disk using a blue light source (around 400 nm) such as S-DVD in the future. can get.

(Embodiment 6) FIG. 8 is an explanatory view of a main part of an optical pickup device according to a sixth embodiment of the present invention, in which light sources 1 and 2, a light receiving element 9, and holograms 10 and 13 are shown. 2 shows an arrangement configuration. Other configurations are shown in FIG.
Is the same as In the fifth embodiment, the hologram 10 is divided into strips, and holograms designed to be optimal for each wavelength are arranged alternately.
In addition to the hologram 10, another hologram 13 is provided so that only one wavelength of light is diffracted twice and condensed at substantially the same point as the other once diffracted light. . In this way, the hologram 10 is first positioned so that the light of wavelength λ ₁ is at the optimum position on the light receiving element 9, and then the hologram 13 has the wavelength λ ₂
Can be positioned such that the light of the light comes to the optimum position on the light receiving element 9. That is, the spots of the wavelength λ ₁ and the wavelength λ ₂ can be adjusted independently.

Therefore, even when the two light emitting points are shifted due to the bonding shift of the LD chip or the like, the adjustment can be performed independently, and the manufacturing tolerance of the LD-PD element 11 can be reduced. In order to guide the light diffracted twice to the light receiving element 9 without waste, if the hologram 13 is formed into a blazed or stair-like shape to increase the diffraction efficiency, the signal light component is not wasted and a high S / N is ensured. Can be.

(Embodiment 7) Next, FIG. 9 is an explanatory diagram of a main part configuration of an optical pickup device showing a seventh embodiment of the present invention. In this embodiment, the entire optical system is the same as in FIG. 1 or FIG. 4, but there is a difference in that a light beam from a light source of one wavelength is converted into three beams. Generally, a CD system (wavelength λ ₂ = 780
nm) tracking is performed by a three-beam method, whereas tracking of a DVD system (wavelength λ ₁ = 635 or 650 nm) is often performed by a one-beam method. This is because the tracking signal is offset. When two laser chips are arranged close to each other and the light emitting points are close, when a diffraction grating is inserted, light of both wavelengths becomes 3
It will be beamed. Therefore, in the present invention, by making use of the fact that the optical element 5 according to the present invention can correct even if the light emitting point is distant, one beam is converted into three beams and the other is formed as one beam, so that optimum signal detection can be performed. Is to do so. More specifically, as shown in FIG. 9, a diffraction grating 12 for three beams is provided at a position 1.5 mm away from the light emitting point.
If there is, the beam diameter at that point is θ = 10 °
Then, 1.5 × tan10 ° = 0.264 mm. Therefore, if the light emitting points of the two LDs are separated from each other by 264 μm or more, the spots do not overlap. Therefore, the diffraction grating 12 for three beams can be arranged to convert one light into three beams. This is not possible when the interval between the light emitting points is reduced to about 100 μm as in the conventional example (1).

[0032]

As described above, according to the present invention, an optical pickup device having a plurality of light sources can be realized. The optical pickup device according to the present invention can be miniaturized, and does not use a special LD for arranging the light emitting points of the semiconductor lasers (LD) of two wavelengths close to each other or use a small prism for synthesizing the two wavelengths. Therefore, cost reduction can be achieved.

More specifically, in the optical pickup device according to the first aspect, the optical means for guiding the light beams from the plurality of light sources to the optical recording medium is an optical element having a total reflection film and a wavelength selection film. It is characterized by not being integrated with multiple light sources contained in one package.Optical elements having a wavelength selection film and a total reflection surface are not provided in the same package as LD and PD. By arranging after the light becomes parallel, it is not necessary to make an expensive small prism that is difficult to process, and the manufacturing accuracy of the prism can be eased. Also, since it is not necessary to use a special LD to bring the light emitting points close to each other, it is suitable for mass production.

In the optical pickup device according to the second aspect,
In an optical pickup device using a diffractive element (hologram), an optical means for guiding light beams from a plurality of light sources to an optical recording medium is an optical element having a total reflection film and a wavelength selection film. Is characterized by not being integrated, and by arranging an optical element having a wavelength selection film and a total reflection surface in the same package as the LD or PD, after being converted into parallel light by a collimating lens,
The same effect as that of the first aspect is obtained, and components such as the hologram and the light receiving element can be shared, so that downsizing and cost reduction can be achieved.

In the optical pickup device according to the third aspect,
In addition to the configuration and effect of the first or second aspect, by arranging the optical element having the wavelength selection film and the total reflection surface in the rising mirror section for guiding the light from the light source to the objective lens, parts can be shared. It is possible to realize cost reduction. Further, in the optical pickup device according to the fourth aspect, in addition to the configuration and effect of the first, second, or third aspect, the optical element having the total reflection film and the wavelength selection film has different beam shaping magnifications depending on the wavelength. By having the shaping function, the beam of one wavelength can be shaped without beam shaping, and the beam of the other wavelength can be shaped with a different magnification.
Since beam shaping can be performed according to the difference in P), light use efficiency can be optimized. Further, since the beam shaping is performed by the rising mirror section, a thin flat beam in the height direction is passed through the optical element, so that the size of the optical element can be reduced accordingly, and the entire optical pickup can be thinned.

In the optical pickup device according to the fifth aspect,
In addition to the configuration and effect of claims 2, 3 or 4, the diffractive element is a hologram having a function of condensing light of each wavelength on substantially the same point of the light receiving element, for example, for each wavelength of a plurality of light sources. By alternately arranging holograms designed for optimization, the light receiving element can be shared and the light receiving area does not need to be large, so the influence of flare is small,
Signal detection can be performed at high speed. Also, since the number of PDs can be reduced, the circuit system is simplified, and the cost of the drive itself can be reduced. In the optical pickup device according to the sixth aspect,
In addition to the configuration and effect of the fifth aspect, there are two diffractive elements (holograms), and light of one wavelength is guided to the light receiving element by receiving two diffraction actions, and the other light is diffracted once. It is characterized by being guided to the light receiving element by the action, of which two diffracted lights from the hologram with different wavelengths are diffracted by another diffraction grating to enter the light receiving element. Thus, after the hologram is assembled and adjusted for one wavelength, the spot position can be adjusted to be optimal for the other wavelength.
Thereby, the bonding error of the LD chip or the PD chip can be compensated at the time of assembling adjustment. Claim 7
In the optical pickup device described above, in addition to the configuration and effect according to any one of claims 1 to 6, a diffraction grating that divides only light of one wavelength out of light from a plurality of light sources having different wavelengths into three. By using the fact that the distance between LDs does not have to be narrow, and by arranging a three-beam diffraction grating so that only one wavelength of light is converted into three beams, the CD system is Tracking can be detected by the three-beam method, and an existing detection circuit such as an LSI can be used.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram in a case where a light beam from a light source of two wavelengths is reflected by a general rising mirror and is incident on an objective lens.

FIG. 3 is a diagram illustrating a case where an optical element having a wavelength selection film and a total reflection film according to the present invention reflects a light beam from a light source of two wavelengths and causes the light beam to enter an objective lens.

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

FIG. 5 is a view showing a fourth embodiment of the present invention, and is an explanatory view in a case where an optical element having a wavelength selection film and a total reflection film has a beam shaping function.

FIG. 6 is an explanatory diagram of a problem that occurs when a hologram is used for a signal detection optical system of an optical pickup device having a light source of two wavelengths.

FIG. 7 is a view showing a fifth embodiment of the present invention, and is an explanatory view of a hologram having a function of condensing light of each wavelength on substantially the same point of a light receiving element.

FIG. 8 is an explanatory diagram of a main configuration of an optical pickup device according to a sixth embodiment of the present invention.

FIG. 9 is an explanatory diagram of a main configuration of an optical pickup device according to a seventh embodiment of the present invention.

[Explanation of symbols]

1: a semiconductor laser (LD) having a wavelength of 635 nm or 650 nm 2: a semiconductor laser (LD) having a wavelength of 780 nm 3: a beam splitter 4: a collimating lens 5: an optical element 5-a: a wavelength selection film 5-b: a total reflection film 5- c: Transmission surface 6: Objective lens 7: Optical recording medium 8: Signal detection optical system 9: Light receiving element (PD) 10: Hologram (diffraction element) 11: LD-PD element 12: 3-beam diffraction grating 13: Hologram ( Diffraction element)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H042 CA01 CA06 CA10 CA14 CA17 2H049 AA03 AA13 AA25 AA57 AA63 AA66 CA05 CA08 CA15 5D119 AA01 AA40 AA41 BA01 BB01 BB04 EC45 EC47 FA08 JA06 JA22 JA26 JA57

Claims (7)

[Claims] A plurality of light sources having different wavelengths each comprising a semiconductor laser, and irradiating a light beam from the plurality of light sources to a recording surface on the optical recording medium via optical means for guiding the light flux to the optical recording medium; In an optical pickup device for writing, erasing, and / or reproducing information while receiving a return light beam reflected by a recording surface by a light receiving element, the optical means for guiding the light beams from the plurality of light sources to an optical recording medium includes total reflection. An optical element having a film and a wavelength selection film,
An optical pickup device which is not integrated with a plurality of light sources contained in one package. 2. A light source comprising a plurality of light sources having different wavelengths comprising a semiconductor laser, and irradiating light beams from the plurality of light sources to a recording surface on the optical recording medium through an optical means for guiding the light flux to the optical recording medium. In an optical pickup device for writing, erasing, and / or reproducing information while diffracting a return light beam reflected by a recording surface by a diffraction element and receiving the light beam by a light receiving element, the light beams from the plurality of light sources are guided to an optical recording medium. The optical means is an optical element having a total reflection film and a wavelength selection film,
An optical pickup device, which is not integrated with a plurality of light sources or light receiving means. 3. The optical pickup device according to claim 1, wherein the optical element having a total reflection film and a wavelength selection film is disposed on a rising mirror portion. 4. An optical pickup device according to claim 1, wherein said optical element having a total reflection film and a wavelength selection film has a beam shaping function in which a beam shaping magnification varies according to a wavelength. Optical pickup device. 5. The optical pickup device according to claim 2, wherein the diffraction element is a hologram having a function of condensing light of each wavelength on substantially the same point of the light receiving element. Pickup device. 6. An optical pickup device according to claim 5, wherein there are two diffractive elements, one of the light having a wavelength is guided to the light receiving element by undergoing two diffraction actions, and the other light is subjected to one light. An optical pickup device, which is guided to a light receiving element by a diffraction effect. 7. An optical pickup device according to claim 1, wherein a diffraction grating for dividing only light of one wavelength out of light from a plurality of light sources having different wavelengths into three is provided. An optical pickup device characterized by being arranged.