JPH11149653A - Light emitting device and optical pickup - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify and to enhance general versatility of a manufacture process of a light emitting device employing an integrated laser beam source, to reduce the manufacture cost for the optical pickup employing the light emitting device, and to reduce the cost for photodetector replacement. SOLUTION: The light emitting device 1 is formed by integrating a laser beam source 2, an optical element 3 acting like a grating with respect to a laser beam L emitted from the laser beam source 2, and an optical element 4 acting like a beam splitter with respect to the laser beam L passing through the optical element 3 on a same substrate 5, but a photodetector is not integrated on the substrate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device in which a laser light source is integrated, and an optical pickup provided with such a light emitting device. About.

[0002]

2. Description of the Related Art In an optical pickup mounted on, for example, a CD (compact disk) player or a DVD (digital video disk) player, its components (laser diode, optical system such as grating, beam splitter, objective lens, etc., photodetector) The following methods existed as methods for constructing ()).

(A) All components are installed as individual components without being integrated (discrete). (B) The laser diode, the grating and beam splitter of the optical system, and the photodetector are integrated on the same substrate.

FIG. 3 shows an example of the configuration of an optical pickup employing the above method (a). The laser diode 11 emits a laser beam L having a wavelength of about 780 nm for CD reproduction. The laser beam L emitted from the laser diode 11 (the optical axis of the laser beam is shown as L for convenience in the drawing. The same applies to the return light L ′ to be described later) by the grating 12.
The beam is split into two main beams and two sub beams, passes through the beam splitter 13, and passes through the collimator lens 14.
After being reflected by the mirror 15 and directed to the recording surface of a CD (not shown) to be reproduced, the light is converged by the objective lens 16 and irradiated onto the recording surface.

The return light L ′ from the recording surface of the CD is reflected by the beam splitter 12 again through the objective lens 16, the 45-degree mirror 15, and the collimator lens 14, and the focal position is adjusted by the multi-lens 17. , Incident on the photodetector 18. A signal processing system (not shown) of the CD player detects a tracking error signal and a focus error signal and a reproduction signal based on the light incident on the photodetector 18.

FIGS. 4 and 5 show an example of the configuration of an optical pickup employing the above method (b). In FIG. 5, the same parts as those in FIG. And redundant description is omitted).

This optical pickup is provided with an integrated unit 21 as shown in FIG. The integrated unit 21 emits a laser beam L having a wavelength of about 780 nm for CD reproduction from a position at a predetermined height on a substrate 26 (for example, a silicon substrate or a metal substrate such as iron) in a lateral direction (to the substrate 26). A laser diode 22 for emitting light in a direction parallel to the surface) is integrated on a substrate 26 via an LOP 27, a grating 23 for separating a laser beam L into a main beam and a sub beam, a beam splitter and a multi-lens. A microprism 24 and a photodetector 25 functioning as a unit are integrated on the same substrate 26.

The laser beam L emitted from the laser diode 22 and separated by the grating 23 is emitted from the integrated unit 21 through the microprism 24, and as shown in FIG.
CD (not shown) through mirror 15 and objective lens 16
The recording surface is irradiated. The return light L 'from the recording surface of the CD returns to the integrated unit 21 via the objective lens 16, the 45-degree mirror 15, and the collimator lens 14 again.
The light enters the photodetector 25 via the microprism 24.

[0009]

However, as shown in FIG. 3, the method (a) has a disadvantage that the number of parts is large and the size is large, and that the optical path of the laser beam is long. There was an inconvenience.

On the other hand, in the above method (b), FIG.
Since the number of components is reduced as compared with the method (a) as described above, miniaturization and shortening of the optical path are realized. However, this method also has the following disadvantages.

(1) The micro-prism and the photodetector must be aligned with high accuracy in the semiconductor manufacturing process for producing an integrated unit, which complicates the manufacturing process.

(2) For an optical pickup using different types of photodetectors, an integrated unit in which the same type of photodetectors are integrated cannot be used in common. Therefore, an integrated type in which the respective types of photodetectors are integrated. You must create a unit. (For example, the arrangement of sensor elements in a photodetector is determined by the type of tracking servo system or focus servo system that is used. It is necessary to create an integrated unit in which the photodetectors of the sensor element array are integrated.) Thus, the integrated unit lacks versatility, and as a result, the manufacturing cost of the optical pickup increases.

(3) When replacing the photodetector due to a failure or the like, since the entire integrated unit must be replaced, the cost required for maintenance also increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and realizes a simplified and general-purpose manufacturing process of a light emitting device (light emitting unit) in which a laser light source is integrated, and an optical device provided with such a light emitting device. An object of the present invention is to reduce the manufacturing cost of the pickup and the cost of replacing the photodetector.

[0015]

A light emitting device according to the present invention comprises a laser light source, an optical element functioning as a grating for a laser beam emitted from the laser light source, and a laser beam passing through the optical element. And an optical element functioning as a beam splitter integrated on the same substrate.

According to this light emitting device, a laser light source;
Optical element that functions as a grating (optical element that separates a laser beam into a main beam and a sub beam)
And an optical element functioning as a beam splitter are integrated on the same substrate, but a photodetector such as a photodetector is not integrated on this substrate.

By not integrating the light detecting means on the same substrate as described above, the optical element and the light detecting means can be positioned with high precision as in a conventional integrated unit in a semiconductor manufacturing process for producing this light emitting device. Since there is no need to match, the manufacturing process is simplified.

Further, this light emitting device has versatility that it can be used in combination with various kinds of light detecting means.

Next, the optical pickup according to the present invention comprises:
A laser light source, an optical element functioning as a grating for the laser beam emitted from the laser light source, and an optical element functioning as a beam splitter for the laser beam passing through the optical element are integrated on the same substrate. And a light detecting means for detecting return light of the laser beam from the optical recording medium is provided separately from the light emitting device.

According to this optical pickup, the light emitting device according to the present invention described above and the light detecting means for detecting the return light of the laser beam emitted from the light emitting device from the optical recording medium are separately provided. Is provided.

Since the light emitting device and the light detecting means are separated as described above, the same kind of light emitting device can be shared for an optical pickup using different types of light detecting means. The manufacturing cost of the optical pickup is reduced accordingly.

Further, since it is not necessary to replace the light emitting device when replacing the light detecting means, the cost required for maintenance is also reduced.

Further, since the laser light source, the optical element functioning as a grating, and the optical element functioning as a beam splitter are integrated, a certain degree of downsizing and shortening of the optical path are realized.

[0024]

FIG. 1 shows an example of the configuration of a light emitting device according to the present invention. The light emitting device 1 emits a laser beam L having a wavelength of about 780 nm for CD reproduction from a position at a predetermined height on a substrate 5 (for example, a silicon substrate or a metal substrate such as iron) in a lateral direction (the surface of the substrate 5). The laser diode 2 emitting in the direction parallel to the
A grating 3 (for example, made of glass or plastic) that is integrated via OP6 and separates a laser beam L into a main beam and a sub beam.
And a beam splitter 4 having a reflecting surface inclined at a fixed angle (for example, an angle between 45 degrees and 60 degrees) with respect to the optical axis of the laser beam L passing through the grating 3 (the optical axis of the main beam). 5 are integrated.

The photodetector is not integrated on the substrate 5. Each part on the substrate 5 is entirely covered with a transparent member (for example, made of glass or plastic) 7 that transmits the laser beam L. The laser beam L that has passed through the grating 3 is reflected by the beam splitter 4 and is emitted from the light emitting device 1 through the transparent member 7 to the outside.

According to the light emitting device 1, since the beam splitter 4 and the photodetector are not integrated on the same substrate 5, the beam splitter 4 and the photodetector are aligned with high precision in the semiconductor manufacturing process as in the related art. No need. Therefore, the manufacturing process is simplified.

The light emitting device 1 has versatility that it can be used in combination with various types of photodetectors.

FIG. 2 shows an example of the entire configuration of an optical pickup provided with the light emitting device 1 of FIG. 1. The same parts as those of FIG. 3 are denoted by the same reference numerals, and redundant description is omitted.
The laser beam L emitted from the light emitting device 1 is supplied to a collimator lens 14, a 45-degree mirror 15, an objective lens 16
Is irradiated onto the recording surface of a CD (not shown). This C
The return light L ′ from the recording surface of D is again transmitted to the objective lens 16,
After passing through the 45-degree mirror 15 and the collimator lens 14, the light-emitting device 1 returns to the beam splitter 4 as shown in FIG.
, Is emitted from the light emitting device 1 again, passes through the multi-lens 17, and enters a photodetector 18 provided separately from the light emitting device 1. (Note that the multi-lens 17
May be omitted. )

According to this optical pickup, since the light emitting device 1 and the photodetector 18 are separate bodies, the same type of light emitting device 1 can be shared for optical pickups using different types of photodetectors. As a result, the manufacturing cost of the optical pickup is reduced accordingly.

Further, since it is not necessary to replace the light emitting device 1 when replacing the photodetector 18, the cost required for maintenance is also reduced.

Further, since the laser diode 2, the grating 3, and the beam splitter 4 are integrated, a certain degree of miniaturization and a shortened optical path can be realized.

Although the grating 3 and the beam splitter 4 are separately arranged on the substrate 5 in the above example,
For example, one holographic element having one surface functioning as a grating and the other surface functioning as a beam splitter is disposed on the substrate 5 (that is, an optical element functioning as a grating and an optical element functioning as a beam splitter). One holographic element may also be used).

Further, in the above example, each part on the substrate 5 of the light emitting device 1 is entirely covered with the transparent member 7, but at least a portion where the laser beam L is emitted from the light emitting device 1 and a return light L 'beam splitter. 4 may be covered with a transparent member, and the other part may be covered with an optically opaque member.
Alternatively, on the contrary, each part on the substrate 5 of the light emitting device 1 may not be covered with any member.

In the above example, a laser diode for emitting a laser beam for reproducing a CD is integrated, but a laser for emitting another appropriate laser beam (for example, a laser beam for reproducing a DVD having a wavelength of about 650 nm) is integrated. The diode may be integrated.

In the above example, both the optical element functioning as a grating and the optical element functioning as a beam splitter are integrated on the same substrate as the laser light source. If it is not necessary to separate the laser beam into the laser beam and the sub beam, only the optical element functioning as a beam splitter may be integrated on the same substrate as the laser light source.

The present invention is not limited to the above embodiment,
It goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0037]

As described above, according to the light emitting device of the present invention, the laser light source, the optical element functioning as the grating, and the optical element functioning as the beam splitter are integrated on the same substrate. The light detecting means is not integrated on this substrate. Therefore, in the semiconductor manufacturing process for producing the light emitting device, it is not necessary to align the optical element and the light detecting means with high accuracy as in the conventional case, and the manufacturing process can be simplified. Also,
This light emitting device has versatility that it can be used in combination with various types of light detecting means.

Next, according to the optical pickup of the present invention, the light emitting device of the present invention and the light detecting means for detecting the return light of the laser beam emitted from the light emitting device from the optical recording medium are provided. Are separate, the same type of integrated unit can be shared for optical pickups using different types of light detecting means, thereby reducing the manufacturing cost of the optical pickup. it can.

Further, when replacing the light detecting means due to a failure or the like, it is not necessary to replace the light emitting device, so that the cost required for maintenance can be reduced.

Further, since the laser light source, the optical element functioning as a grating, and the optical element functioning as a beam splitter are integrated, it is possible to realize a certain degree of downsizing and shortening of the optical path.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an example of a configuration of a light emitting device according to the present invention.

FIG. 2 is a diagram illustrating an example of an overall configuration of an optical pickup provided with the light emitting device of FIG.

FIG. 3 is a diagram illustrating an example of the entire configuration of a conventional optical pickup.

FIG. 4 is a diagram showing an example of a configuration of a conventional integrated unit.

FIG. 5 is a diagram illustrating an example of the overall configuration of a conventional optical pickup.

[Explanation of symbols]

Reference Signs List 1 light emitting device, 2,11,22 laser diode, 3,12,23 grating, 4,13 beam splitter, 5,26 substrate, 6,27 LO
P, 7 Transparent member, 18, 25 Photodetector, 14 Collimator lens, 15 45 degree mirror, 16 Objective lens, 17 Multi lens, 2
1 integrated unit, 24 microprisms

Claims (2)

[Claims] 1. A substrate comprising: a laser light source; an optical element functioning as a grating for a laser beam emitted from the laser light source; and an optical element functioning as a beam splitter for a laser beam passing through the optical element. Light emitting device integrated on top. 2. A substrate comprising: a laser light source; an optical element functioning as a grating for a laser beam emitted from the laser light source; and an optical element functioning as a beam splitter for a laser beam passing through the optical element. An optical pickup comprising: an integrated light emitting device provided thereon; and light detecting means for detecting return light of the laser beam from an optical recording medium provided separately from the light emitting device.