Patent Application
20080106999
This application claims priority to Japanese Patent Application No. 2006-261534, which was filed on Sep. 26, 2006, the contents of which are incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a semiconductor laser apparatus which is preferably mounted on an optical disk recording/reproducing apparatus, a method for manufacturing the same, and an optical pickup apparatus using the same.
2. Description of the Related Art
The optical pickup apparatus for recording and reproducing data in an optical drive such as a compact disk (CD) drive, or a digital versatile disk (DVD) drive includes a semiconductor laser element as a light source, and a light-receiving element for receiving a reflected light beam from a disk. A laser beam emitted from the light source is adjusted so that a size of its light spot becomes smallest on a recording surface of a CD or a DVD. The laser beam reflected on the recording surface is received on a photodetector in the optical pickup apparatus, and is then converted to data.
Laser beams having wavelengths of 790 nm, 650 nm, and 405 nm are used for CDs, DVDs, and next-generation DVDs such as a blue-ray disk or a high definition digital versatile disk (HD DVD), respectively. The optical pickup drive corresponding to a plurality of standards mounts the plurality of optical pickup apparatuses, or the optical pickup apparatus which incorporates a plurality of laser light sources. Further, there is proposed a special recording medium called a digital versatile disk-random access memory (DVD-RAM), which is capable of recording on lands and grooves thereof.
In a semiconductor laser apparatus according to the related art, an optical element sub-carrier on which a light-emitting element is mounted is surrounded by a frame, and a lower-end face side of a base-lead including a mounted portion of the light-emitting element is in contact with a bottom portion of the frame (refer to Japanese Unexamined Patent Publication JP-A 9-21723 (1997)).
When the semiconductor laser apparatus disclosed in JP-A 9-21728 (1997) operates, the light-emitting element produces heat upon emitting a laser beam. The lower-end face side of the base-lead including the mounted portion of the light-emitting element is in contact with the bottom portion of the frame, and additionally the frame is mounted on the housing. Therefore, the heat generated from the light-emitting element is conducted through the mounted portion of the light-emitting element, the base-lead, and the frame to a main body of the housing, and is discharged from the main body of the housing. However, it is difficult to sufficiently discharge the heat generated from the light-emitting element, only by discharging the heat from the main body of the housing. Therefore, when the semiconductor laser apparatus is used over a long time period, the light-emitting element may possibly be gradually deteriorated, resulting in a reduction of its reliability and its lifetime. In addition, the optical axis of the output light beam emitted from the light-emitting element is deviated under an influence of distortion of the housing through the base-lead and the frame. Therefore, reliability of the semiconductor laser apparatus is reduced.
Further, the semiconductor laser apparatus 20 shown in
An object of the invention is to provide a semiconductor laser apparatus capable of sufficiently discharging heat generated at a semiconductor laser element, of being manufactured in a simple manufacturing step, and of adjusting an optical path length, as well as a method for manufacturing the same.
The invention provides a semiconductor laser apparatus comprising:
a plate for connecting with a housing;
a block connected to one surface of the plate which is perpendicular to a thickness direction thereof; and
a laser chip which is connected to a surface opposite to a surface of the block to which the plate is connected,
wherein the plate is provided with an exposed portion which is partially exposed in the surface of the plate to which the block is connected, and an optical axis of an output light beam of the laser chip is perpendicular to the thickness direction of the plate.
According to the invention, the laser chip is connected to the block, and the block is connected to the plate for connecting with the housing. Therefore, the laser ship is less affected by mechanical distortion of the housing than it is directly connected to the housing. Further, the plate is partially exposed from a connecting surface between the block and the plate, and thereby the semiconductor chip, a circuit board, and the block are inserted from an outside of the housing, and the exposed portion of the plate is connected to an outside surface of the housing. The plate is exposed outwardly from the housing, and thereby heat generated from the semiconductor laser chip in the housing is efficiently discharged through the block to the plate, and to an outside of the housing. Accordingly, deterioration of the semiconductor laser apparatus is prevented, and thereby its reliability is improved, and its lifetime is increased. Further, the laser chip is fixed to a surface parallel to the optical axis of the output light beam, and thereby it is possible to adjust a position on the surface parallel to the optical axis of the output light beam by adjusting a position of the through-hole which is provided in the housing. By adjusting a position as described above, it is possible to adjust an optical path length from a light-emitting position of a laser beam to a light-irradiated position thereof, without changing a size of the housing.
Further, in the invention, it is preferable that the semiconductor laser apparatus further comprises a circuit board which is connected to a surface of the block which surface is opposite to the surface of the block to which the plate is connected, and the laser chip and the circuit board are electrically connected to each other.
According to the invention, the circuit board is further connected to the block, and is electrically connected to the laser chip. By mounting the circuit board on the block, a small-footprint is achieved.
Further, in the invention, it is preferable that the circuit board is a flexible board.
According to the invention, the circuit board is a flexible printed circuit board (abbreviated as a FPC), and the FPC is a flexible board which has a structure that a circuit formed by precisely etching a copper foil is coated with a polyimide film excellent in an insulating property and a heat-resisting property. The FPC is easily machined, and incorporates an electronic circuit in a narrow space. Therefore, electronic apparatuses are downsized, and a degree of freedom with respect to a board shape is improved.
Further, in the invention, it is preferable that the exposed portion is symmetric with respect to a center point of the surface of the block to which the plate is connected.
According to the invention, the exposed portion is symmetric with respect to a center point of the surface of the block to which the plate is connected. Therefore, when the semiconductor laser apparatus is inserted from an outside of the housing and fixed to the housing, the connecting portion with the outside surface of the housing becomes symmetric, thereby further improving stability of the connection.
Further, in the invention, it is preferable that the exposed portion is symmetric with respect to a straight line passing though a center point of the surface of the block to which the plate is connected, and perpendicular to a thickness direction of the plate.
According to the invention, the exposed portion is symmetric with respect to a straight line passing though a center point of the surface of the block to which the plate is connected, and perpendicular to a thickness direction of the plate. Therefore, when the semiconductor laser apparatus is inserted from an outside of the housing and fixed to the housing, the connecting portion with the outside surface of the housing becomes symmetric, thereby further improving stability of the connection.
Further, in the invention, it is preferable that the surface of the block to which the plate is connected is entirely connected to the plate, and an area of the surface of the plate to which the block is connected is larger than that of the surface of the block to which the plate is connected.
According to the invention, the surface of the block to which the plate is connected is entirely connected to the plate, and the area of the surface of the plate to which the block is connected is larger than that of the surface of the block to which the plate is connected. One surface of the block is entirely connected to the plate, and the plate has a wide area, and thereby an efficiency of heat discharge is improved. Moreover, stability of the connection with the housing is improved.
Further, in the invention, it is preferable that the laser chip is connected through a sub-mount member to the block, and the sub-mount has good heat conductivity, good heat discharge capability, and a buffering function.
According to the invention, the laser chip is connected through the sub-mount member to the block, and the sub-mount has significantly high heat conductivity, is excellent in heat discharge capability, and has a buffering function for reducing a breakdown caused by stress produced by a difference in a heat expansion coefficient between the block and the semiconductor laser chip. Therefore, deterioration of the semiconductor laser apparatus is prevented, and thereby its reliability is improved and its lifetime is increased.
Further, The invention provides a group of the semiconductor laser apparatuses comprising:
an elongated plate;
a plurality of blocks which are connected to one surface of the elongated plate which is perpendicular to a thickness direction of the elongated plate in a line at certain intervals in a longitudinal direction of the elongated plate; and
a laser chip which is connected to a surface opposite to a surface of the block to which the elongated plate is connected,
wherein an optical axis of an output light beam of the laser chip is perpendicular to the thickness direction of the elongated plate.
According to the invention, the plurality of blocks which are connected to the surface perpendicular to the thickness direction of the elongated plate of the group of the semiconductor laser apparatuses in a line at certain intervals in the longitudinal direction of the elongated plate, and the laser chip is mounted on each block. By making production and inspection regarding the block connected to the plate as a unit, simplification of production steps can be realized.
Further, the invention provides a method for manufacturing the semiconductor laser apparatus comprising the steps of:
providing the group of the semiconductor laser apparatuses mentioned above; and
dividing the elongated plate of the group of the semiconductor laser apparatuses between the adjacent blocks.
Further, according to the invention, the elongated plate of the group of the semiconductor laser apparatuses to which the plurality of blocks are connected is divided between the adjacent blocks with respect to each block, as individual semiconductor laser apparatuses. The elongated plate is divided after all components necessary for the semiconductor laser apparatus are mounted thereon, thus enabling simplification of production steps and improvement of transporting efficiency.
Further, the invention provides an optical pickup apparatus comprising:
the semiconductor laser apparatus mentioned above; and
a housing having a through-hole,
wherein an area of opening of the through-hole is larger than that of a surface perpendicular to a thickness direction of the block, and at least the laser chip of the semiconductor laser apparatus is inserted into the through-hole so as to be positioned in the housing, and the exposed portion is fixed to an outside surface of the housing so as to partially overlap with each other.
Further, according to the invention, at least the laser chip of the semiconductor laser apparatus is inserted into the through-hole so as to be positioned in the housing, and the exposed portion is fixed to the outside surface of the housing so as to partially overlap with each other. By exposing the plate of the semiconductor laser apparatus outwardly from the housing, heat generated from the semiconductor laser chip is discharged from the plate, and thereby an efficiency of heat discharge is improved compared with heat discharge from a main body of the housing in a conventional manner. Therefore, the heat generated from the semiconductor laser apparatus is sufficiently discharged, and thus deterioration of the semiconductor laser apparatus is prevented, and thereby its reliability is improved and its lifetime is increased.
Further, the laser chip is fixed to a surface parallel to the optical axis of the output light beam, and thereby it is possible to adjust a position on the surface parallel to the optical axis of the output light beam by adjusting a position of the through-hole which is provided in the housing. By adjusting the position as described above, an optical path length from a light-emitting position of a laser beam to a light-irradiated position thereof is adjusted, without changing a size of the housing. Therefore, there is provided the optical pickup apparatus corresponding to various wavelengths.
Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein:
Hereinafter, referring to the drawings, preferred embodiments of the invention will be described in detail.
That is, the plate 1 has a shape which has convex portions 1b projecting in a width direction at four corners of a base body 13 having a rectangular shape, and the block 2 having a rectangular parallelepiped shape is connected to a center portion of the base body 13. That is, the center portion of the base body 13 corresponds to the connection portion 1a. In addition, the laser chip 3 is connected to the block 2 so that an elongated direction of the block 2 is in parallel to the optical axis of the output light beam.
The semiconductor laser apparatus 21 is manufactured by individually dividing the one in which the semiconductor laser apparatuses have been connected to each other in a form of a ladder. Before dividing it, the convex portions 1b of the plate 1 are connected to convex portions 1b of the plate of the adjacent semiconductor laser apparatus. The plate 1 and the block 2 contain, for example, a metal material in order to ensure a discharge capability for heat generated from the laser chip 3.
A laser chip 3 is connected to a block 2, and the block 2 is connected to a plate 1 for connecting with a housing of an optical pickup apparatus. Accordingly, the laser ship 1 is less affected by mechanical distortion of the housing than it is directly connected to the housing. Further, the plate 1 is partially exposed from a connecting surface between the block 2 and the plate 1, and thereby when disposed in the housing, the semiconductor chip 3 and the block 2 are inserted from an outside of the housing, and the exposed portion 11 of the plate 1 is connected to an outside surface of the housing. The plate 1 is exposed outwardly from the housing, and thereby the heat generated from the laser chip 3 in the housing is efficiently discharged trough the block 2 to the plate 1, and to an outside of the housing. Accordingly, deterioration of the semiconductor laser apparatus can be prevented, and thereby its reliability can be improved, and its lifetime can be increased. Further, an optical axis of an output light beam of the laser chip 3 is perpendicular to a thickness direction of the plate 1, that is, in parallel to a ground plane of the housing, and thereby it becomes possible to adjust a position on the surface parallel to the optical axis of the output light beam by adjusting a position of the through-hole which is provided in the housing. By adjusting a position as described above, it becomes possible to adjust an optical path length from a light-emitting position of a laser beam to a light-irradiated position thereof, without changing a size of the housing.
In a semiconductor laser apparatus 20 shown in
Further, as shown in
The through-hole 9 is provided to have a long length in the output direction of the light beam, allowing easy movement of the semiconductor laser apparatus 23 in the output direction of the light beam. Accordingly, the adjustment range is further increased to allow easy adjustment. However, in order to allow such movement of the semiconductor laser apparatus 23, it is necessary to provide an exposed portion 11 of the plate 1 in a width direction of the plate 1. In addition, by previously providing the plurality of through-holes 9, selecting the appropriate through-hole 9, and fixing the semiconductor laser apparatus 23 thereto, it becomes easy to adjust the optical path length.
A shape of the exposed portion 11 of the semiconductor laser apparatus 32 shown in
A shape of the exposed portion 11 of the semiconductor laser apparatus 33 is symmetric with respect to a straight line passing though a center point of the surface of the block 2 to which the plate 1 is connected, and perpendicular to a thickness direction of the plate 1. Therefore, when the semiconductor laser apparatus is inserted from an outside of the housing and fixed to the housing, the connecting portion with the outside surface of the housing becomes symmetric, thereby further improving stability of the connection.
In the semiconductor laser apparatus 34 shown in
The elongated plate 12 has a ladder shape, and has a first extended portion 12a and a second extended portion 12b which extend in a longitudinal direction thereof so as to be parallel to each other and provided at an interval in a width direction thereof, and a plurality of third extended portions 12c which are provided at a certain interval in the longitudinal direction between the first extended portion 12a and the second extended portion 12b. The plurality of third extended portions 12c are coupled on the first extended portion 12a and the second extended portion 12b on both sides thereof, respectively. The respective third extended portions 12c become the connection portion 1a of the plate 1. That is, the elongated plate 12 is provided with a plurality of holes 12d at certain intervals in the longitudinal direction, in a middle portion in the width direction, and the blocks 2 having rectangular parallelepiped shapes are connected to portions in which the holes are not provided, that is, the third extended portions 12c. The elongated plate 12 is a base holder having a ladder shape. By means of a production system of the semiconductor laser apparatus, the base holder on which the base is mounted can be linearly moved along a linear rail, and a movement of the base from the base holder to a production processing apparatus, and a movement of the base from the production processing apparatus to the base holder can be carried out by using an arm. Therefore, this production system has a simple structure, sure operation, and a high production efficiency. Further, an optical axis of an output light beam from the laser chip 3 is perpendicular to a thickness direction of the elongated plate 12. The plurality of blocks 2 are connected to a sheet of the elongated plate 12 having a ladder shape, thereby facilitating a series of steps such as a set-up of components or an inspection.
There will be described a method for dividing the group of the semiconductor laser apparatuses between the blocks 2, and manufacturing the semiconductor laser apparatus. First, the group of the semiconductor laser apparatuses 40, as described above, is provided, and finally, the elongated plate 12 of the group of the semiconductor laser apparatuses 40 is divided between the adjacent blocks 2 to obtain the semiconductor laser apparatus. A dividing position of the elongated plate 12 may be selected anywhere as long as it is located between the adjacent blocks 2. The elongated plate 12 is preferably divided at a center position between the adjacent blocks 2. The exposed portions 11 of the plate 1 of the semiconductor laser apparatuses which are obtained after the separation have all the same shapes, allowing a stable supply of products having the same quality. In addition, a shape of the exposed portion 11 becomes symmetric, thereby increasing stability when the semiconductor laser apparatus is disposed in the housing.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-261534 | Sep 2006 | JP | national |
