Abstract: A hearing aid comprises a battery compartment prepared for receiving a battery (10) and two contacts (4) arranged to draw an electrical current from an inserted battery in order to power electrical parts of the hearing aid. At least one of the contacts (4) is loaded by a pre-stressed spring (1), which comprises a body part (2) and a torque part (3), said body part (2) being arranged in a fixed attachment in a first end from where it extends to the point of battery contact in a second end, where the torque part (3) is adapted to provide a torque to the point of contact (4).

Abstract: A hearing aid comprises a battery compartment prepared for receiving a battery (10) and two contacts (4) arranged to draw an electrical current from an inserted battery in order to power electrical parts of the hearing aid. At least one of the contacts (4) is loaded by a pre-stressed spring (1), which comprises a body part (2) and a torque part (3), said body part (2) being arranged in a fixed attachment in a first end from where it extends to the point of battery contact in a second end, where the torque part (3) is adapted to provide a torque to the point of contact (4).

Abstract: A three dimensional (3D) track ball system includes a housing having top wall with a circular aperture. A track ball is rotatably mounted in the housing so as to protrude through the aperture. In a preferred embodiment, three supporting elements in the housing rotatably support the track ball. The supporting balls are mounted and journalled in positions in which their respective centers are located in a plane that is parallel with the top wall of the housing, and define an equilateral triangle that is coaxially aligned with the aperture. The centers of the supporting balls are located relative to the center of the track ball so as to define an orthogonal coordinate system, including three orthogonal coordinate axes.