JP3035077B2 - Package for semiconductor laser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor laser package, and more particularly to a semiconductor laser package used for a portable optical disk player requiring a thin optical pickup.

[0002]

2. Description of the Related Art As a conventional semiconductor laser package, a package as shown in FIG. 5 is generally used. As a method of assembling this semiconductor laser package, a circular plate-shaped metal stem 1 having an outer diameter of 5.6 mmφ or 9 mmφ is usually used.
01, a semiconductor laser chip 102 serving as a light source,
A PIN photodiode 103 for monitoring the output light from the semiconductor laser chip 102 is fixed by die bonding.

Next, a glass sealing portion 104 is attached to the stem 101.
The semiconductor laser chip 102 and the PIN photodiode 103 are electrically connected to the lead pins 105 which are insulated and fixed by the metal wires 106, respectively. And
In order to cut off the semiconductor laser chip 102 and the PIN photodiode 103 from the external atmosphere, a metal cap 108 having a glass window 107 for emitting laser light is covered, and the cap 108 is fixed to the upper surface of the stem 101 by resistance welding.

FIG. 6 shows a semiconductor laser package used in a conventional hologram laser unit.
This package consists of a circular metal stem 1
The semiconductor laser chip 111
And a signal reading photodiode 112, and a monitor PIN photodiode 113 on the stem 109,
Both are fixed by die bonding.

Each optical component has a metal wire 11
At 4, it is electrically connected to the lead pin 116 which is insulated and fixed by the glass sealing portion 115 on the stem 109.
Then, the glass window 1 for emitting laser light is
The metal cap 118 provided with the metal cap 17 is covered, and the cap 118 is fixed to the upper surface of the metal stem 109 by resistance welding.

[0006] On the upper surface of the cap 118, the glass plate 11
9 is fixed with an epoxy resin. Glass plate 119
Includes a diffraction grating pattern for generating three beams, and a hologram pattern provided to guide return light from an optical disk (not shown) to the signal reading photodiode 112 in the package.

FIG. 7 schematically shows an optical pickup using the semiconductor laser package of FIG. Semiconductor laser 1 incorporated in housing 120 of optical pickup
The light emitted from 21 passes through a collimator lens 122 and a beam splitter 123 and is then focused on an optical disk 125 by an objective lens 124. The return light from the optical disk 125 is transmitted to the objective lens 124 and the beam splitter 12.
3. The light passes through the convex lens 126, is focused on the signal reading photodiode 127, and is converted into an electric signal. Also,
As a modification of the optical pickup shown in FIG. 7, there is an optical pickup in which a reflecting mirror inclined by 45 ° is added between the beam splitter 123 and the objective lens 124 to make the optical pickup thinner.

FIG. 8 schematically shows an optical pickup using the hologram laser unit shown in FIG. The laser light emitted from the hologram laser unit 129 incorporated in the housing 128 of the optical pickup passes through a glass plate 130 provided with a diffraction grating for beam generation and a hologram pattern for beam deflection, a collimating lens 131, and a reflecting mirror 132. Is focused on the optical disk 134 by the objective lens 133. The return light from the optical disk 134 is focused on the signal reading photodiode in the hologram laser unit 129 through the above-described reverse path,
Converted to electrical signals.

This hologram laser unit 129
When incorporated into the housing 128, the optical disk 13
In order to accurately read the servo signal on the hologram laser unit 4, the entire hologram laser unit 129 is rotated to adjust its mounting position, and then fixed to the housing 128 with resin or the like.

[0010]

However, in a semiconductor laser package used in a conventional hologram laser unit, a semiconductor laser chip, a monitor PIN photodiode, and a signal reading photodiode are contained in one package. Since it is built-in, the number of lead pins of the package increases, and its outer diameter becomes 9 mmφ. When this package is incorporated into an optical pickup of an optical disk player, the thickness of the pickup becomes 9 mm or more. For this reason, the thickness of the portable thin optical disk player body has also been increased, and its handleability and portability have been impaired.

An object of the present invention is to reduce the size of a package while maintaining the performance of a hologram laser unit having excellent environmental resistance, and to reduce the thickness of a conventional optical pickup which does not use a hologram laser unit to a minimum thickness of 7 mm. An object of the present invention is to provide a semiconductor laser package used for a hologram laser unit for realizing a thin optical pickup.

[0012]

SUMMARY OF THE INVENTION The present invention provides a semiconductor laser chip as a light source, a PIN photodiode for monitoring a laser beam emitted from the semiconductor laser chip, and a photodiode for reading a signal from an optical disk. Are placed on the same plate-like stem, and a cap is attached to the stem so as to cover these optical elements.
In a semiconductor laser package for a hologram laser unit, wherein a glass substrate having a light-deflecting diffraction grating formed on a top surface of a cap is attached, the stem has a flat shape formed by two opposing portions forming a part of a circle. And a substantially elliptical shape surrounded by two opposing arcs and two opposing chords. The mounting surface of the semiconductor laser chip is aligned with the direction of the chords.
Parallel and adjacent to the parallel direction
A package for a semiconductor laser, wherein a package is arranged . In addition, the stem may include a plurality of ribs.
A lead pin, and a part of the lead pin extends in the direction of the string.
A package for a semiconductor laser, wherein the package is arranged in parallel with the semiconductor laser.

That is, in the semiconductor laser package of the present invention, in a metal stem for fixing a semiconductor laser chip, a monitor PIN photodiode and a signal reading photodiode by die bonding, the respective die bonding portions are the same as those of the prior art, and various optical bonding is performed. The arrangement of the elements is the same as the conventional one. Thereby, the basic performance of the hologram laser unit is maintained. Then, the arrangement of the lead pins is changed from the conventional circular shape to a substantially oval shape, and the outer diameter of the stem is formed from the conventional circular shape to a substantially oval shape in accordance with the arrangement of the lead pins, and at the same time, the cap is also changed from the circular shape to a substantially elongated shape. The gist is to form a circular shape. Thus, the package is thinned.

In the semiconductor laser package according to the present invention, since the position of the light emitting point of the semiconductor laser chip coincides with the center position of the stem determined from the arc portion of the substantially elliptical plate-like stem, the servo on the optical disk is The package rotation adjustment for accurately reading the signal can be easily performed. Further, by using the arc portion as a reference position of the semiconductor laser chip, it is possible to easily couple with another optical component such as a lens.

[0015]

The thickness of the optical pickup can be reduced by using the substantially oval portion of the semiconductor laser package in the horizontal direction. At the same time, since the weight of the optical pickup is reduced, the thickness and weight of the optical disk player can be reduced, which is optimal for a portable optical disk player. In addition, by reducing the thickness and weight of the optical pickup, the access speed of the optical pickup can be improved. Further, since the light emitting point of the semiconductor laser chip coincides with the center of the circle of the substantially elliptical semiconductor laser package, the rotation adjustment when the package is incorporated into the optical pickup can be easily performed, and the optical pickup can be assembled. The process can be simplified.

Further, the planar shape of the stem is not a conventional circular shape but a substantially elliptical shape having a straight portion. Therefore, since the stem can be securely fixed when assembling the semiconductor laser chip, the monitor PIN photodiode, the signal reading photodiode, and the like, accurate assembly is possible.

[0017]

An embodiment of the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited by this. In FIG. 1, a hologram laser unit using a semiconductor laser package includes a substantially oval stem 1 made of metal, a substantially oval cap 2, and a glass plate 3 on which a diffraction grating pattern is engraved.

FIG. 2 shows the inside of the stem 1 as viewed from above. The semiconductor laser chip 4, the monitor PIN photodiode 5, and the signal reading photodiode 6 are die-bonded, respectively, and are electrically connected to the lead pins 8 by metal wires 7. The outer diameter is 4.8 mm in the thickness direction of the optical pickup and 8.2 mm in the lateral direction. The light emitting point of the semiconductor laser chip 4 coincides with the center of φ8.2 mm, and when the hologram laser unit is incorporated in the optical pickup, the rotation can be easily adjusted.

3 and 4 schematically show an optical pickup using the semiconductor laser package according to the present invention.
The laser light emitted from the hologram laser unit 10 incorporated into the housing 9 of the optical pickup by rotation adjustment passes through a glass plate 11 on which a beam generation diffraction grating and a beam deflecting hologram pattern are engraved, and then passes through a collimating lens. The light passes through 12 and the reflecting mirror 13 and is condensed on the optical disk 15 by the objective lens 14.

The return light from the optical disk 15 is diffracted by the hologram pattern engraved on the upper surface of the glass plate 11 along the reverse path. Then, the light is collected by the signal reading photodiode 6 of the hologram laser unit and is converted into an electric signal.

As a result, a semiconductor laser package having a conventional thickness of 9 mm can be reduced to a thickness of 4.8 mm. That is, the hatched portion indicated by 16 in FIG. 3 has been deleted, and it has become possible to manufacture an optical pickup having a thickness of 5 mm.

[0022]

According to the present invention, since the outer diameter of the stem can be reduced, it is possible to manufacture an optical disk pickup whose thickness is as thin as possible. Further, since the weight of the optical pickup can be reduced, the access speed can be improved. In addition, since the center of the outer diameter coincides with the position of the light emitting point of the semiconductor laser chip, it is possible to easily adjust the rotation when the hologram laser unit is incorporated into the optical pickup. In addition, since the stem is provided with the straight portion, the alignment between the assembly center of the laser assembly device and the stem center can be easily performed. Further, since the stem can be securely fixed to the assembly device, accurate assembly can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view of a hologram laser unit using a package according to one embodiment of the present invention.

FIG. 2 is a plan view of a stem portion of the package.

FIG. 3 is a schematic structural explanatory view of an optical pickup incorporating a hologram laser unit using the package as viewed from the front.

FIG. 4 is a schematic configuration explanatory view of the optical pickup viewed from a side.

FIG. 5 is a perspective view of a conventional general semiconductor laser package.

FIG. 6 is a perspective view of a conventional package for a hologram laser unit.

FIG. 7 is a schematic explanatory diagram of an optical pickup using a conventional semiconductor laser package.

FIG. 8 is a configuration explanatory view of an optical pickup using a conventional hologram laser unit.

[Explanation of symbols]

 Reference Signs List 1 stem 2 cap 3 glass plate 4 semiconductor laser chip 5 PIN photodiode 6 photodiode 7 wire 8 lead pin 9 pickup housing 10 hologram laser unit 11 glass plate 12 collimating lens 13 reflecting mirror 14 objective lens 15 optical disk

Continued on the front page (72) Inventor Taiji Morimoto 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Shigehiro Yamada 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56 ) References JP-A-4-24978 (JP, A) JP-A-1-313987 (JP, A) JP-A-1-313988 (JP, A)

Claims (2)

(57) [Claims] A semiconductor laser chip serving as a light source, a PIN photodiode for monitoring laser light emitted from the semiconductor laser chip, and a photodiode for reading a signal of an optical disk are formed of the same plate-shaped stem. A semiconductor laser package for a hologram laser unit, which is disposed on a cap attached to a stem while covering these optical elements and a glass substrate on which a diffraction grating for light deflection is formed on the upper surface of the cap, The stem has a substantially elliptical shape whose plane shape is surrounded by two opposing arcs and two opposing chords that can be obtained by removing two opposing arcs that form a part of a circle. And the mounting surface of the semiconductor laser chip is parallel to the direction of the chord.
As a result, a photodiode is placed adjacent to the parallel direction.
A semiconductor laser package characterized by being arranged . 2. The stem has a plurality of lead pins.
A part of the lead pin is arranged parallel to the direction of the string.
The package for a semiconductor laser according to claim 1, wherein: