Abstract: An electromagnetic braking device includes a brake disk, a fixed disk, an armature, a biasing member for biasing the armature, and a stator for attracting the armature. In a stator magnetic circuit member, a first yoke, a permanent magnet, and a second yoke are arranged in this order from one end to the other end of a U shape. In a rotatable state or a rotation braking state, even when the coil energization is OFF, the rotatable state or the rotation braking state is maintained. When a current of a predetermined magnitude flows through the coil in a first direction in the rotatable state, the state shifts to the rotation braking state, and when a current of a predetermined magnitude flows through the coil in a second direction in the rotation braking state, the state shifts to the rotatable state.

Abstract: In an objective lens for an optical head apparatus for reading or writing an information on a recording medium such as optical disc, astigmatism is added on axial wavefront aberration so that off-axis astigmatism is to be cancelled by the axial astigmatism. At least one surface of the objective lens is a toric or cylindrical surface, and a standard deviation of astigmatism component of axial wavefront aberration is defined as Wa is to be restricted in a range of 0<Wa<0.07.lambda. (.lambda. is a wavelength of a light to be used). When the objective lens moves in a radial direction of the optical disc, a light beam enters into the objective lens in an off-axis region where the aberration is compensated by the axial astigmatism.

Abstract: A developing apparatus has a toner reservoir for holding a non-magnetic toner, a toner supply roller including a supply surface for receiving the toner from the toner reservoir and electrifying the toner thereon, an electrostatic latent image carrier including a curved or flat latent image surface on which a latent image formed by an electrostatic voltage distribution thereon is developed by the toner transferred from the supply surface, and a toner seal surface arranged adjacent to the toner supply roller to contact a remaining part of the toner on the supply surface after the latent image development so that the remaining part of the toner is taken into the toner reservoir. The respective frictional coefficients between the toner seal surface and the toner and between the toner particles are selected to prevent a disturbance of toner condition between the toner and the toner seal surface.

Abstract: This invention relates to a carrier for developing electrostatic latent images comprising;carrier core particles having specified physical properties such as mean particle size, a bulk density, ratio of small particles, surface area index and the like, andresin-coating layers formed of specified components at specified content by a sintering process so that the layer resin may have specified physical properties such as ratio of integrated intensity and the like.

Abstract: A resin composition is described consisting essentially of from 0.5 to 100 parts by weight of a water-soluble polyamide and from 0.5 to 100 parts by weight of a vinyl alcohol-based polymer. The resin composition has excellent transparency and can be used, for example, to form light-sensitive resin compositions and adhesives.