System and Method of Obective Lens Selection in a Multiple Lens Actuator

Abstract

The invention relates to a system comprising: a source for generating a light beam (B), an optical element (M) intended to receive said light beam (B), an actuator (AC) in which is mounted a plurality of objective lenses (OL0, OL1 . . . ), translation means for translating said optical element (M) so as to direct said light beam (B) toward a given objective lens taken among said plurality of objective lenses (OL0, OL1 . . . ).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

An embodiment of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating an optical scanning device according to the prior art for dual layer read-out with a dual lens;

FIG. 2 is a schematic diagram illustrating a monolithic dual lens for use in an optical scanning device according to the prior art for dual layer read-out;

FIG. 3 is a schematic diagram illustrating the principle components of an optical storage system according to the prior art;

FIG. 4 is a schematic plan view illustrating the operation of a pole actuator for use in a dual lens optical scanning device according to the prior art;

FIG. 5 is a schematic plan view illustrating the operation of a translation addressing system for use in a dual lens optical scanning device according to the prior art;

FIG. 6 is a known method for mounting a dual lens in respect of an optical storage system;

FIG. 7 is a schematic side view illustrating the operation of a dual lens addressing system in which a polarizing beamsplitter and a polarization switch are provided on the actuator; and

FIG. 8 is a schematic diagram illustrating an optical scanning device according to a first exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 8 depicts an embodiment of a system according to the present invention. This System comprises:

a source for generating a light beam B,an optical element M intended to receive said light beam B,an actuator AC in which is mounted a plurality of objective lenses OL0, OL1 . . . ,translation means for translating said optical element M so as to direct said light beam B toward a given objective lens taken among said plurality of objective lenses OL0, OL1 . . . .

The optical element (M) may advantageously correspond to a reflective element, or to a fold mirror.

By translating the optical element M, by means for example of translation means such as a linear translation motor (not shown) or a sledge guided on axis and moved by an actuator (not shown), the optical element M being located on the so-called ‘fixed world’ (i.e. on parts of the system having a fixed position relative to an optical disc), the light beam is alternatively reflected toward the lens OL1 or the lens OL0.

The actuator AC can move the dual lens assembly in the radial and focus directions. The actuator movement is uncoupled to the optical element displacement. If the optical element M is in position P1, the light beam B is directed to the lens OL1. Translation along the arrow T displaces the optical element M from position P1 to position P0, so that lens OL0 is now addressed. In other words, a translation of the optical element M leads to a translation of the light beam.

Thus, the present invention provides an arrangement in which the lenses of a multi lenses actuator are addressed by means of translation of the beam with respect to the assembly of the lenses in such a way that the means by which such translation is effected are not provided on the actuator itself.

The objective lens to be addressed may be identified by a control signal intended to be applied to the translation means, and reflecting the data layer required to be read or written by the addressed lens, which control signal may simply consist of a logical zero or one.

This arrangement avoids undue complication of the actuator by internally moving parts and also avoids any increase in size and weight of the actuator caused by the provision of such addressing means.

The invention also relates to a method of directing a light beam B toward a given objective lens taken among a plurality of objective lenses OL0, OL1 . . . which are mounted in an actuator AC, said method comprising the step of translating an optical element (M) intended to receive said light beam B so as to direct said light beam B toward said given objective lens.

It will be appreciated that the present invention, while it has been described above in relation to a dual lens actuator arrangement, can be generalised to apply to the addressing of multiple (i.e. >2) lenses.

Such a sytem and method may advantageoulsy be implemented in an optical reading and/or writing apparatus.

It should be noted that the above-mentioned embodiment illustrates rather than limits the invention, and that those skilled in the art will be capable of designing many alternative embodiments without departing from the scope of the invention as defined by the appended claims. In the claims, any reference signs placed in parentheses shall not be construed as limiting the claims. The word “comprising” and “comprises”, and the like, does not exclude the presence of elements or steps other than those listed in any claim or the specification as a whole. The singular reference of an element does not exclude the plural reference of such elements and vice-versa. The invention may be implemented by means of hardware comprising several distinct elements, and by means of a suitably programmed computer. In a device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. System comprising: a source for generating a light beam (B),an optical element (M) intended to receive said light beam (B),an actuator (AC) in which is mounted a plurality of objective lenses (OL0, OL1 . . . ),translation means for translating said optical element (M) so as to direct said light beam (B) toward a given objective lens taken among said plurality of objective lenses (OL0, OL1 . . . ).

2. Optical reading and/or writing apparatus comprising: a source for generating a light beam (B),an optical element (M) intended to receive said light beam (B),an actuator (AC) in which is mounted a plurality of objective lenses (OL0, OL1 . . . ),translation means for translating said optical element (M) so as to direct said light beam (B) toward a given objective lens taken among said plurality of objective lenses (OL0, OL1 . . . ).

3. System according to claim 1, wherein said optical element (M) comprises a reflective element.

4. System according to claim 3, wherein said reflective element comprises a fold mirror.

5. A method of directing a light beam (B) toward a given objective lens taken among a plurality of objective lenses (OL0, OL1 . . . ) which are mounted in an actuator (AC), said method comprising the step of translating an optical element (M) intended to receive said light beam (B) so as to direct said light beam (B) toward said given objective lens.