JP2509333Z - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an objective lens device used for optically reading information recorded on a recording medium such as a disk. (Prior Art) Recently, in this type of objective lens device, there has been a tendency to reduce the size, particularly the thickness of the objective lens device. Are arranged and combined with a reflection member. The proposed objective lens device has a base on which a yoke and a magnet are provided on a bottom surface and a magnetic circuit is formed by the yoke and the magnet, an objective lens is held above the base, and the objective lens is arranged in the optical axis direction of the objective lens. A lens holder movably supported, a focusing coil mounted on the lens holder and moving the lens holder in the optical axis direction of the objective lens in conjunction with the magnetic circuit; A reflecting member that reflects light from a light source incident from a direction perpendicular to the optical axis in the optical axis direction of the objective lens and guides the light to the objective lens, and suppresses the size of the objective lens in the optical axis direction to be small. The overall thickness was reduced. (Problems to be Solved by the Invention) However, in the above-mentioned conventional objective lens device, since the magnetic circuit exists on the bottom surface of the base, the reflecting member is arranged below the bottom surface of the base, and the optical axis of the objective lens is arranged. The optical path of light incident from a direction perpendicular to the direction is secured, and its configuration is a hindrance for reducing the size of the objective lens in the optical axis direction, that is, promoting further reduction in thickness, and it is impossible to further reduce the thickness. Had become something. However, the present invention achieves further reduction in thickness by devising the positions of the reflection member and the magnetic circuit. (Means for Solving the Problems) In order to achieve the above object, the present invention provides a base having a yoke and a magnet on a bottom surface to form a magnetic circuit with the yoke and the magnet, and an objective lens above the base. And a lens holder supported so as to be movable in the optical axis direction of the objective lens, and mounted on the lens holder, and coupled with the magnetic circuit, the lens holder is moved in the optical axis direction of the objective lens. A focusing coil for moving the objective lens, and a reflecting member that reflects light incident from a direction perpendicular to the optical axis of the objective lens in the optical axis direction of the objective lens and guides the reflected light to the objective lens. The magnetic circuit is disposed at a position overlapping the bottom surface of the base and the magnetic circuit when viewed from a direction orthogonal to the optical axis of the objective lens, and the objective lens is incident from outside the apparatus. It is provided at a position that does not hinder light from a direction orthogonal to the optical axis of the laser. (Operation) In the above configuration, when the bottom surface of the base and the magnetic circuit overlap the reflecting member when viewed from a direction orthogonal to the optical axis of the objective lens, the size of the objective lens in the optical axis direction can be reduced, and the overlapping portion is reduced. As the size increases, the width of reduction can be increased. In addition, an optical path from the direction orthogonal to the optical axis of the objective lens to the reflecting member can be ensured, and light can be reflected by the reflecting member and reliably guided to the objective lens. (Embodiment) Hereinafter, an embodiment of the present invention shown in the drawings will be described in detail. 1 and 2, reference numeral 1 denotes a base, a support shaft 2 is provided upright at the center, and an opening 3 through which light passes is formed on the bottom surface. At positions sandwiching the support shaft 2, outer yokes 4 and 4 for focusing are erected, and support pieces 5a and 5b are erected and magnets 6 and 6 for tracking are attached. A lower portion of one of the support pieces 5a is curved to allow light to pass through, and a relief portion 7 is formed. The relief portion 7 is continuous with the opening 3. Reference numerals 8 and 8 denote inner yokes for focusing, and 9 and 9 denote magnets for focusing, which are overlapped with each other to form a magnetic circuit together with the outer yokes 4 and 4. Reference numeral 10 denotes a lens holding cylinder (lens holding body) having an objective lens 11 mounted on the top surface and a bearing hole 12 formed therein. 11 (optical axis direction). Further, a focusing coil 13 is wound around the peripheral surface of the lens holding cylinder 10, and tracking coils 14, 14 are adhered so as to face each other. Reference numeral 15 denotes a prism mirror (reflection member) disposed in the opening 3 on the bottom surface of the base 1 so as to be substantially at the same height as the bottom surface of the base 1, and a part thereof is viewed from a direction orthogonal to the optical axis of the objective lens 11. It is positioned so as to overlap magnets 9, 9 which are components of the magnetic circuit. Thus, the light from the light source enters the prism mirror 15 through the escape portion 7 and the opening 3 from a direction orthogonal to the optical axis of the objective lens 11. The objective lens 11 reflects at right angles to the axial direction.
The magnetic circuit components such as the outer yokes 4 and 4, the inner yokes 8 and 8, and the magnets 9 and 9, which are provided on the bottom surface of the base 1, are arranged in a prism perpendicular to the optical axis of the objective lens 11. The base 1 does not interfere with the light incident on the mirror 15.
Is provided on the bottom surface. As described above, in the above-described embodiment, the prism mirror 15 is connected to the objective lens 11.
Is arranged so as to overlap the magnetic circuit when viewed from a direction orthogonal to the optical axis of the objective lens 11.
Light from the outside of the apparatus, which is incident from a direction perpendicular to the optical axis of the objective lens 11, can be incident on the prism mirror 15 without being hindered by the magnetic circuit, reflected at right angles to the optical axis direction of the objective lens 11, and guided to the objective lens 11. . Therefore, as compared with the conventional objective lens, the dimension of the objective lens 11 in the optical axis direction can be reduced by the thickness of the base 1 and the dimension of the overlapping portion between the magnetic circuit and the prism mirror. Can be further promoted. (Effects of the Invention) As described above, in the objective lens device of the present invention, the magnetic circuit is configured so as not to block light from the direction orthogonal to the optical axis of the objective lens that enters from outside the device. Thereby, without incorporating the light source of the light leading to the objective lens into the objective lens device,
The reflecting member is disposed so as to overlap the bottom surface of the base and the magnetic circuit when viewed from a direction perpendicular to the optical axis of the objective lens, and the light from the direction perpendicular to the optical axis of the objective lens, which is incident from the outside of the device, is transmitted to the magnetic circuit Accordingly, the light can be made incident on the reflection member without hindrance. Therefore, the overall size of the device, particularly, the thickness can be further reduced without lowering the function.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional side view of an objective lens device according to an embodiment of the present invention, and FIG. 2 is an exploded perspective view of the same. DESCRIPTION OF SYMBOLS 1 ... Base, 3 ... Opening, 4 ... Focusing coil, 7 ... Escape part, 8 ... Focusing inner yoke, 9 ... Focusing magnet, 10 ... Lens holding cylinder (Le 13 ... Focusing coil, 15 … Prism mirror (reflective member)

Claims (1)

[Claims for utility model registration] A base on which a yoke and a magnet are provided on a bottom surface and a magnetic circuit is formed by the yoke and the magnet; and a lens holder which holds the objective lens above the base and is movably supported in the optical axis direction of the objective lens. A focusing coil mounted on the lens holder and moving the lens holder in the direction of the optical axis of the objective lens in conjunction with the magnetic circuit; and a focus coil which is incident from a direction perpendicular to the optical axis of the objective lens. A reflecting member for reflecting light in an optical axis direction of the objective lens and guiding the light to the objective lens, wherein the reflecting member is viewed from a direction orthogonal to the optical axis of the objective lens, and a bottom surface of the base and the magnetic circuit. The magnetic circuit is provided at a position where it does not block light from a direction orthogonal to the optical axis of the objective lens, which is incident from the outside of the apparatus, while overlapping with the magnetic circuit. An objective lens device according to.