This invention relates to a method of fixing a laser diode to an optical base and to an optical pickup using the optical base.
As a recording medium for use with an electronic apparatus such as a personal computer, a CD-R (compact disc recordable) and a CD-RW (compact disc rewritable) are known. The CD-R is a recording medium which allows an additional writing operation to be repeatedly carried out. The CD-RW is a recording medium which allows a rewriting operation to be repeatedly carried out. Each of the CD-R and the CD-RW is compatible with a CD-ROM (compact disc read only memory), an audio CD (CD-DA) (compact disc digital audio), a DVD-ROM (digital versatile disk read only memory), and a DVD-RAM (digital versatile disk random access memory). Writing into the CD-R or the CD-RW requires a special apparatus and a writing application program. On the other hand, reading from the CD-R or the CD-RW can be executed by an ordinary CD-ROM drive. In the present specification, the CD-R, the CD-RW, the CD-ROM, the audio CD, the DVD-ROM, and the DVD-RAM may collectively be called an optical disk.
In order to write and read data into and from the optical disk, an optical pickup is used. The optical pickup of the type comprises a laser diode for emitting a laser beam and an optical system for directing the laser beam to the optical disk. Typically, the laser diode and the optical system are fixed to a common optical base.
Existing methods of fixing the laser diode are classified into first through third methods (1)-(3) as follows.
(1) To simply fit the laser diode to the optical base.
(2) To provide the laser diode with a flange and to adjust only angles of the laser diode in several directions (in many cases, only in a horizontal direction).
(3) To position the laser diode by 5 axes 3D adjustment know in the art and to fix the laser diode by the use of an adhesive.
However, the first through the third methods mentioned above have disadvantages which will be described below. In the first method, it is possible to provide a pickup which is simple in structure and low in cost. However, it is difficult to improve the positional accuracy of the laser diode. The second method is excellent in heat release because heat is diffused via the flange. However, this method requires a complicated mechanism so that the adjustment of the laser diode in multiple directions is difficult and a large space is required. The third method is excellent in fixing accuracy but is poor in heat release. Therefore, this method is not suitable for a high-output laser diode.
It is therefore an object of the present invention to provide a method of fixing a laser diode to an optical base, which is capable of easily improving a positional accuracy of the laser diode, which can be implemented by a simple structure, and which does not inhibit heat release.
It is another object of this invention to provide an optical pickup which Is high in positional accuracy of a laser diode, which is simple in structure, and which is excellent in heat release.
Other objects of the present invention will become clear as the description proceeds.
According to an aspect of the present invention, there is provided a method of fixing a laser diode to an optical base. The method comprises the steps of screwing and fixing a plural number of threaded pins to the optical base, facing the laser diode to the optical base in an area between the threaded pins, adjusting a position and an angle of the laser diode with respect to the optical base, and soldering and fixing the laser diode to the threaded pins. The above-mentioned steps are sequentially carried out in this order.
According to another aspect of the present invention, there is provided an optical pickup which comprises an optical base, a plural number of threaded pins screwed and fixed to the optical base, a laser diode faced to the optical base in an area between the threaded pins and adjusted in position and angle with respect to the optical base, and a soldering portion fixing the laser diode to the threaded pins.