JPH06150351A - Movable optical unit - Google Patents

Abstract

PURPOSE:To obtain a movable lens optical unit capable of making a whole optical system thin in structure and having an excellent operating characteristic. CONSTITUTION:In a recording medium 1 having an information track, by irradiating the track with a beam through an objective lens 3, following the track this movable optical unit of an information recording/reproducing device performs recording, reproducing or erasing. This unit comprizes a holding member 4 for objective lens, a suspension 5 for elastically supporting the holding member for objective lens, a balancer for compensating the weight balance of the supported part by the suspension, a magnetic circuit 8, driving coils 6, 7 fixed on the holding member for objective lens and driving the holding member for objective lens in cooperation with the magnetic circuit at least in the direction of the optical axis among the optical axis direction of the objective lens and the direction orthogonal to the optical axis direction and a reflection mirror 10 for deflecting a light beam parallel with the moving direction of the movable optical unit to the optical axis direction of the objective lens. The objective lens fixing part of the holding member for objective lens is projected on the side of the holding member for objective lens and the mirror is arranged in the vicinity just below the objective lens.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording and / or reproducing apparatus, in which an information track of a recording medium is irradiated with a beam for recording and reproducing information, and
The present invention relates to a movable optical unit that controls so as to follow.

[0002]

2. Description of the Related Art In this type of movable optical unit, in order to form a beam spot on a desired track on a recording medium, conventionally, a structure as shown in FIGS. 4 to 6 has been adopted. Here, FIG. 4 shows a plan view of a conventional movable optical unit and a main part of the optical information recording / reproducing apparatus, and FIG. 5 shows a cross section thereof as viewed from the side, In FIG. 6 it is shown from the left side. The objective lens 3 for irradiating a beam to form a beam spot on the disk-shaped recording medium 1 held on the turntable 2 is held by a lens holder 4, and also the lens holder 4
Are supported by the wire spring 5 which is an elastic member.
Then, the lens holder 4 has a focus coil 6,
The tracking coil 7 is fixed, and cooperates with the magnetic circuit 8 to drive the lens holder 4 in the optical axis direction of the objective lens 3 and in a direction orthogonal to that direction.

On the other hand, the light flux emitted from the fixed optical unit 11 is directed in a direction perpendicular to the recording medium surface by a folding mirror 10 mounted on a carriage 9 which guides the movable optical unit movably in the radial direction of the disk. Reflected in. Then, the objective lens 3 converges the beam so that a beam spot having a desired size is formed on a desired track on the recording surface.

Reflected light from the recording medium is returned from the movable optical unit to the fixed optical unit 11 via the objective lens 3 and the bending mirror 10, and is received via optical elements such as various prisms and lenses. It is given to the element and used to detect an error signal of a focal position of a beam spot or a track position and a recording signal.

[0005]

By the way, with the miniaturization of personal computers, the information recording / reproducing apparatus used as a secondary recording apparatus thereof has a small size.
Thinning is required. However, in the configuration of the conventional movable optical unit as described above, since the bending mirror 10 and the lens holder 4 are configured to overlap each other in the height direction, the movable optical unit is about the thickness of the lens holder. The overall height is increased, which in turn increases the size of the information recording / reproducing apparatus in the height direction, which hinders the reduction in thickness of the apparatus.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a movable lens optical unit having a thin optical system and excellent dynamic characteristics.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a lens holder, which is supported by an elastic member, which holds an objective lens and projects laterally from a main body of the lens holder. In addition, a reflection mirror is arranged immediately below the reflection mirror, and a suspension that elastically supports the objective lens holding member is provided.

[0008]

With the above-mentioned means, the light beam coming from the direction parallel to the moving direction of the movable optical unit is bent in the optical axis direction of the lens by the reflecting mirror directly below the objective lens, and the driving coil is biased. The objective lens is driven in the direction of the optical axis and in a direction perpendicular to the direction of the optical axis to focus and follow the beam so as to form a beam spot on a desired track. In addition, the weight can be balanced without increasing the size of the lens holding member.

[0009]

Embodiment An embodiment of the present invention will be described below with reference to the drawings.
This will be specifically described. 1 to 3 show an embodiment of the present invention. Here, the main parts of the movable optical unit and the optical information recording / reproducing apparatus in the present invention are shown. In particular, in this embodiment, the same configurations as those of the conventional example described above are designated by the same reference numerals. Attached. Here, the objective lens 3 for irradiating a beam onto the disc-shaped recording medium 1 on the turntable 2 is held by a lens holder 4, and the lens holder 4 is made of an elastic member 5.
It is supported by the carriage 9. The focus coil 6 and the tracking coil 7 are fixed to the lens holder 4, and the magnetic circuit 8 is attached to each of them.
In cooperation with the lens holder 4, the lens holder 4 is driven in the optical axis direction of the objective lens 3 and in the direction orthogonal to this direction. As shown in FIG. 2, the objective lens 3 is held by the lens holder at a position laterally protruding from the upper part of the coil winding portion. That is, the objective lens 3 is configured as a lens holder at a position offset from driving means such as a focus coil and a tracking coil. Therefore, the folding mirror 10
Can be arranged immediately below the objective lens 3 and on the carriage 9, and the optical axis height of the fixed optical system can be
It can be accommodated within the height of the movable optical unit, and the height of the entire optical system can be reduced. Here, reference numeral 12 is a balance weight, which is the driving force point of the focus coil 6 or the tracking coil 7.
The mass and the position of the driving force are determined so that the driving force point and the center of gravity of the movable portion of the optical system coincide with each other. It is preferable that the objective lens 3 is on a straight line connecting the intersection of the driving force line of the focus coil 6 and the driving force line of the tracking coil 7 and the center of gravity of the objective lens 3 and opposite to the objective lens 3 with the intersection point as the center. A balance weight may be provided at a position on the lens holding member 4. For this reason, even a moving part having an asymmetrical shape can be dynamically balanced, and a dynamic lens tilt of the objective lens, which often causes a problem, can be prevented by a lens actuator of a supporting system using an elastic member. is doing. In this way, according to the present embodiment, the height of the entire optical unit can be reduced without degrading the dynamic characteristics of the movable optical unit.

[0010]

As described above, the present invention provides a lens movable optical unit of a supporting type using an elastic member,
By configuring the objective lens at a position that protrudes to the side of the objective lens holding member and allowing a reflecting mirror to be placed immediately below it, the horizontal optical axis height of the optical system can be moved. Since the height can be within the height of the optical unit, the overall optical system can be thinned. By providing a balancer that corrects the weight balance of the movable part supported by the suspension, the weight balance can be achieved without increasing the size of the lens holding member, which is excellent while making the entire optical system thin. It is possible to obtain a movable optical unit including a lens actuator having dynamic characteristics.

[Brief description of drawings]

FIG. 1 is a plan view showing essential parts of a movable optical unit and an optical information recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 2 is a side sectional view of FIG. 1 seen from below.

FIG. 3 is a side view of FIG. 1 viewed from the left.

FIG. 4 is a plan view showing essential parts of a movable optical unit and an optical information recording / reproducing apparatus according to a conventional example.

5 is a side sectional view of FIG. 4 seen from below.

FIG. 6 is a side view of FIG. 4 as viewed from the left.

[Explanation of symbols]

 1 Disc-shaped recording medium 2 Turntable 3 Objective lens 4 Lens holder 5 Wire spring 6 Focus coil 7 Tracking coil 8 Magnetic circuit 9 Carriage 10 Bending mirror 11 Fixed optical unit 12 Balance weight

Claims (1)

[Claims] 1. A movable optical unit of an information recording / reproducing apparatus, wherein a recording medium having an information track is recorded / reproduced or erased by following / irradiating a beam onto the track with an objective lens. An objective lens holding member, a suspension that elastically supports the objective lens holding member, a balancer that corrects the weight balance of a portion supported by the suspension, a magnetic circuit, and a fixed to the objective lens holding member, A coil that cooperates with the magnetic circuit to drive the objective lens holding member in at least the optical axis direction of the direction orthogonal to the optical axis direction of the objective lens, and a light flux parallel to the moving direction of the movable optical unit. A reflecting mirror that deflects in the optical axis direction of the objective lens, wherein the objective lens fixing portion of the objective lens holding member is Projects to the side of the object lens holding member, the movable optical unit, characterized in that arranged the reflecting mirror in the vicinity immediately below the objective lens.