Optical head device having an objective lens holder supported by composite wires and single wires
View Patent ↗An optical head device including a lens holder which holds an objective lens, six wires for supporting the lens holder and a holder support member which movably supports the lens holder by the six wires in a tracking, focusing and tilt direction. The six wires comprise two pairs, each of the pairs comprising a composite wire composed of two wires and a single wire composed of one wire which are respectively disposed on an upper side and a lower side of the lens holder in the focusing direction. The spring constant of the composite wire is set to be approximately equal to a spring constant of the single wire. Alternatively, the six wires may be disposed on the same circumference with respect to a drive center in the tilt direction or the spring constant of one wire of the pair may be set to be smaller than spring constants of the other two wires of the pair.
1. An optical head device comprising:
an objective lens for converging an emitted beam from a light source to an optical recording medium;
a lens holder for holding the objective lens;
a plurality of wires for supporting the lens holder; and
a holder support member for movably supporting the lens holder by the plurality of wires in a tracking direction, a focusing direction and a tilt direction;
said plurality of wires comprising two pairs, each of the pairs further comprising a composite wire composed of two wires and a single wire composed of one wire which are respectively disposed on an upper side and a lower side of the lens holder in the focusing direction, each pair being disposed on both sides of the lens holder in the tracking direction, the base end sides of the composite wire and the single wire being respectively fixed to the holder support member and the front end sides of the composite wire and the single wire being respectively fixed to the lens holder, and a spring constant of the composite wire being set to be approximately equal to a spring constant of the single wire.
2. The optical head device according to claim 1 , wherein the length of single wire and the length of one wire of the composite wire of each pair are set to be approximately equal to each other and the length of the other wire of the composite wire is set to be longer than that of the one wire of the composite wire.
3. The optical head device according to claim 2 , wherein the single wire and the composite wire of each pair are respectively fixed and connected to a wiring pattern of a circuit board which is mounted on the holder support member, the single wire and the one wire of the composite wire being respectively fixed at a same fixing position provided on the lens holder, and the other wire of the composite wire being fixed on the lens holder at a further more front side position than the fixing position provided on the lens holder.
4. The optical head device according to claim 3 , wherein the single wire and the one wire of the composite wire are soldered to wiring patterns of a circuit board provided on a front side of the lens holder, and wherein a fixed position to the lens holder of the other wire of the composite wire is a soldered position to a wiring pattern of a circuit board provided on the front side of the lens holder.
5. The optical head device according to claim 1 , wherein the respective spring constants of the single wires of two pairs are set to be equal to each other.