Optical: systems and elements – Lens – With support
Reexamination Certificate
2000-01-26
2001-04-10
Mack, Ricky (Department: 2873)
Optical: systems and elements
Lens
With support
Reexamination Certificate
active
06215604
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an optical lens which is held by a lens holder, particularly, relates to an optical lens which is capable of being easily fitted in a cavity of a lens holder with high positioning accuracy.
As well known, an electronic data processing equipment such as a personal computer is connected to various peripheral devices which include a memory device. As the memory device, an optical disk memory device can be used.
The optical disc memory device is, for example, a CD-R drive which can write/read data to/From a CD-R (compact disc recordable) as a recording medium by using a laser beam. The CD-R is a write-once optical disc that allows additional writing many times but does not allow erasing data recorded thereon. The CD-R can be used for a CD-ROM or a CD-DA (audio CD) because the data recorded thereon can be read by a normal CD-ROM drive.
The optical disc memory device has an optical pickup to apply the laser beam on a surface of the recording medium and to detect the reflection from the surface. The optical pickup includes a laser beam source for emitting the laser beam, an object or optical lens for gathering the laser beam from the laser beam source on the surface of the recording medium, and a lens holder for holding the object lens.
The lens holder has a through-hole for passing the laser beam through therein. A part of the through-hole serves as a cavity for receiving the object lens. Generally, the cavity is larger than the other part of the through-hole in inner diameter.
In a conventional technique, the object lens is fitted in the cavity of the lens holder by a running (or free) fit method or an interference fit method.
In the running fit method, there is a problem that it is difficult to put the object lens in a desired position of the cavity. In other wards, the running fit method can not position the object lens to the lens holder with high positioning accuracy. This is because there is a gap between a peripheral or outer side surface of the object lens and an inner side surface of the cavity. When the object lens is not in the desired position, it is impossible to obtain desired optical characteristics for the optical pickup.
On the other hand, the interference fit method does not have such a problem as the running fit method. However, the interference fit method has another problem that it is necessary to press the object lens with large pressing force in the cavity. The large pressing force deforms the object lens and deteriorates optical characteristics for the optical pickup.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an optical lens which is capable of being easily fitted in a cavity of a lens holder with high positioning accuracy.
It is another object of this invention to provide a lens holder which is suitable for the above mentioned optical lens.
Other object of this invention will become clear as the description proceeds.
On describing the gist of this invention, it is possible to understand that an optical lens is fitted in a cavity of a lens holder and fixed thereto. The cavity has a predetermined inside diameter.
According to the gist of this invention, the optical lens comprises a lens body having a peripheral surface and an outside diameter smaller than the predetermined inside diameter. A projection is formed on the peripheral surface and protrudes to a radial direction for interfering with a fitting of the lens body in the cavity without resistance.
According to another gist of this invention, a lens holder is for holding the above mentioned optical lens. The lens holder comprises a first section having the cavity with a trench which is for partially receiving the projection when the optical lens is fitted in the cavity. A second section is continuous with the first section and has a hole which is continuous with the cavity and which has an inside diameter smaller than the outside diameter of the lens body.
According to still another gist of this invention, an optical lens has a lens body which has a peripheral surface and an outer diameter. A projection is formed on the peripheral surface and protrudes in a radial direction of the optical lens. A lens holder has a cavity which has an inner diameter larger than the outer diameter to receive the lens body. A method of fixing of the optical lens to the lens holder comprises the steps of placing the optical lens in front of the cavity, and pressing the optical lens in the cavity while deforming the projection thereby.
REFERENCES:
patent: 4662717 (1987-05-01), Yamada et al.
patent: 5024509 (1991-06-01), Kurihara et al.
patent: 5396487 (1995-03-01), Abe et al.
patent: 5608579 (1997-03-01), Nomura
patent: 196 23 418 A1 (1997-12-01), None
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mack Ricky
Mitsumi Electric Co. Ltd.
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