Abstract: An optical pickup apparatus comprising a first objective lens that focuses first laser light on an information recording layer of a first optical disc in a first mounting state where the first optical disc is mounted on a turntable; a second objective lens that focuses second laser light on an information recording layer of a second optical disc in a second mounting state where the second optical disc is mounted on the turntable, the second optical disc having an information recording format different from that of the first optical disc; and a lens holder that integrally holds the first objective lens and the second objective lens in an adjacent manner on the outside and inside, respectively, along a radial direction of the first optical disc in the first mounting state and of the second optical disc in the second mounting state, the lens holder being shiftable along the radial direction, a disc surface of the first optical disc in the first mounting state and of the second optical disc in the second mounting

Abstract: An objective lens holding device includes a first objective lens, a second objective lens, and a lens holder, wherein an axis-to-axis distance between a central axis of the first objective lens and a central axis of the second objective lens is set to a distance, depending on a first length and a second length, which distance prevents a second edge portion from butting against a turntable when the first objective lens focuses light from a first laser on an innermost circumference of the information recording layer of an optical disc.

Abstract: A lens driving apparatus comprising: a first lens-barrel having a lens built thereinto; a second lens-barrel; an electromechanical conversion element that applies a driving force f1 to the first lens-barrel and a driving force f2 to the second lens-barrel; and a housing that supports the lateral surfaces of the first lens-barrel and the second lens-barrel such that a lens-barrel body is mounted slidably on the housing in the light axis direction of the lens, the lens barrel body being the first lens-barrel and the second lens-barrel connected via the electromechanical conversion element therebetween, wherein the electromechanical conversion element generates deformation which results in displacement in the light axis direction of the lens by applying a drive voltage, and wherein the first lens-barrel generates an inertia force IF1 and a friction force FF1 with the support surface of the housing by applying the driving force f1, and wherein the second lens-barrel generates an inertia force IF2 and a friction f

Abstract: A yoke constituting a magnetic actuator for driving an objective lens has a plurality of arms arranged in a plane intersecting the optical axis of the lens perpendicular thereto. An optical system including the objective lens is disposed at one side of the yoke and has the outer peripheral portion of the lens positioned partly in the space between adjacent two arms. The lateral width of the device is decreased by an amount corresponding to the lap of the lens over the yoke. A cover plate is secured to the upper surface of the magnetic actuator in intimate contact with the upper end faces of the yoke arms to give enhanced rigidity to the device.

Abstract: A small-sized electric mechanical transducer wherein plates are disposed to surround a bobbin in association with yokes. Magnetic passages are formed among the plates. Each of a pair of magnets drives the bobbin in accordance with the electric signals input into the driving coil. Also, an optical type pickup apparatus positively capable of the signal reading operation in which the lens holder is not out of shape even if the lens holder is driven in the focusing direction and the tracking direction, because the gravity center of the lens holder is conformed to the action point of the resultant force of the forces to be produced by the control signals to be input into the driving coil, and by the magnetic field of the magnetic circuit.

Abstract: A optical type pickup apparatus wherein the center of gravity of the lens holder coincides with the action point of the resultant force of the forces to be produced by the control signals input into the driving coil and by the magnetic field of the magnetic circuit. Thus, this apparatus may be provided which is capable of a signal reading operation wherein the lens holder is not out of shape even if the lens holder is driven in the focusing direction and the tracking direction.

Abstract: An optical pickup device in which a laser light source is so disposed that one of two dividing lines of a photo-detector having at least four sensing portions symmetrically divided by the dividing lines so as to detect focusing deviation of a light beam onto a signal surface of a record disc, is aligned with the tangential direction of the signal track at the portion where the light beam is projected onto the signal surface, whereby the optical pickup is free from a wrong focusing control due to erroneous detection even during track jumping.

Abstract: A diaphragm for a dynamic cone speaker which is composed of a porous metal produced from a metal such as nickel, wherein a layer, such as of aluminum foil, is disposed on a surface of the porous metal to eliminate the gas permeability of the porous metal.

Abstract: A diaphragm for a dynamic cone speaker which is composed of a porous metal produced from nickel powder wherein a vinyl chloride sheet is disposed on the surface of the porous metal to eliminate the gas permeability of the porous metal.