Dynamic information storage or retrieval – Dynamic mechanism subsystem – Specified detail of transducer assembly support structure
Reexamination Certificate
1997-07-10
2001-01-23
Miller, Brian E. (Department: 2757)
Dynamic information storage or retrieval
Dynamic mechanism subsystem
Specified detail of transducer assembly support structure
C369S247100
Reexamination Certificate
active
06178155
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an optical pickup which is indispensable part for an information reproducing apparatus (disc player) for playing a CD (compact disc) and a DVD (digital video disc).
A compact disc (hereinafter referred to as CD) comprises a plastic layer (having a thickness of 1.2 mm) on which audio or video signals are recorded in the form of numerous information pits, a metal reflecting layer formed on the plastic layer, and a protection layer formed on the reflecting layer.
A digital video disc (hereinafter referred to as DVD) comprises two information layers on each of which signals are recorded in the form of numerous information pits, each having a thickness of 0.6 mm. Such a DVD is capable of recording a much larger amount of information than a CD.
Although a CD and a DVD are different from each other in their specifications, a CD drive of a CD player has many similarities with a DVD drive of a DVD player. Thus, there has been suggested an optical disc player which has two optical pickups adapted to play a CD and a DVD, using only a single disc drive.
However, in the optical disc player designed to play a CD and a DVD, since there are two optical pickups, two sets of moving mechanisms are required to respectively move the two optical pickups in disc radial direction. As a result, it is difficult for a disc player to be made compact.
In view of the above, a more compact player has been demanded which has only a single optical pickup capable of playing not only a CD but also a DVD. For instance, the single optical pickup is made into two-focus pickup capable of emitting an optical beam for playing both a CD and a DVD (whose protection layers are different from each other in thickness). However, in a case where a two-focus optical pickup is employed in a disc player, if there is an inclining angle between the recording surface of an optical disc and the optical axis of the optical beam, a comatic aberration will occur in the optical beam when irradiating an optical disc. in order to correct such a comatic aberration, a pickup including an actuator is moved in disc radial direction or disc tangential direction, thereby eliminating the inclining angle between the recording surface of an optical disc and the optical axis of an optical beam.
On the other hand, since an optical beam for DVD and an optical beam for CD are caused to pass through an identical objective lens with different incident angles, an attempt to eliminate a comatic aberration occurring in one optical beam will undesirably promote a comatic aberration occurring in the other optical beam. Namely, it is difficult to eliminate two kinds of comatic aberration occurring in two optical beams.
In order to solve the above problem, at first the pickup body is caused to incline to some extent to eliminate a comatic aberration occurring in one optical beam. Then, the actuator of the pickup body is caused to incline to some extent in a direction in which a comatic aberration occurs in the other optical beam. Further, it is also possible to have the pickup body inclined to at the same time eliminate the above two kinds of comatic aberration occurring in the above two optical beams.
It is understood from the above explanation that, in order to correct two kinds of comatic aberration occurring in two optical beams, it is necessary to establish a construction where the pickup body of the two-focus pickup may be made inclined with respect to the recording surface of an optical disc. For instance, it is required that the pickup body be divided into a main pickup body and a sub-pickup body, both of which are pivotably connected with each other, such that the main pickup body may be made inclined so as to correct the above comatic aberration.
However, in a construction where the main pickup body and a sub-pickup body are pivotably connected with each other, a resonance phenomenon will occur in both the main pickup body and the sub-pickup body due to a vibration from the outside, resulting in a problem that information can only be reproduced with a deteriorated precision.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved optical pickup capable of reproducing information from an optical disc with a high precision even if there is a vibration from the outside, so as to solve the above-mentioned problems peculiar to the above-mentioned prior arts.
According to the present invention, there is provided an optical pickup for use in an information reproducing apparatus for playing an optical disc, said optical pickup comprising: a main pickup body carrying an objective lens; a sub-pickup body pivotably connected with the main pickup body; a connecting structure formed in connection with the main pickup body for pivotably supporting the sub-pickup body. A groove having a predetermined size is formed between the main pickup body and the connecting structure. The material thickness between the main pickup body and the connecting structure is made thinner by virtue of the formation of said groove.
In detail, the above connecting structure is connected to the sub-pickup body through a support portion of the sub pickup body. The support portion of the sub-pickup body is formed with a screw hole into which a screw is engaged. Similarly, the connecting structure is also formed with a screw hole. Thus, a screw engaged in the screw hole of the support portion of the sub-pickup body is engaged into the screw hole of the connecting structure.
The above objects and features of the present invention will become more understood from the following description with reference to the accompanying drawings.
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patent: 5084854 (1992-01-01), Ikedo et al.
patent: 5124973 (1992-06-01), Igata
patent: 5172361 (1992-12-01), Urushibata et al.
patent: 5703864 (1997-12-01), Miyagi et al.
patent: 5726968 (1998-03-01), Blankers
patent: 7-114735 (1995-05-01), None
Fujinoki Shinichi
Sasanuma Shigeyuki
Suzuki Jun
Ueda Osamu
Fields Kenneth W
Miller Brian E.
Morgan & Lewis & Bockius, LLP
Pioneer Electronic Corporation
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