Abstract: An outer ring case includes an annular guide groove housing an end of each of a plurality of inner rollers. A groove width representing a radial length of the guide groove is greater than a diameter of each inner roller. A radius representing a distance from a bearing axis to an inner wall face of the guide groove that is radially outer is smaller than a distance from the bearing axis to an axial center of each of rollers plus a radius of each inner roller.

Abstract: A speaker includes a main-cone and a sub-cone. Linear thin portions configured to reduce a plate thickness of the sub-cone are formed on a region containing at least any one of an outer side and an inner side of the sub-cone. Each of the linear thin portions has both of a component in a radial direction and a component in a circumferential direction of the sub-cone. First and second linear thin portions cross each other at an intersection. With this configuration, stiffness of the whole sub-cone is reduced to enhance a divided vibration of the sub-cone. In particular, a vibrational displacement of an outer peripheral portion of the sub-cone, from which a sound is mainly radiated, is increased.

Abstract: A speaker includes a main-cone and a sub-cone. Linear thin portions configured to reduce a plate thickness of the sub-cone are formed on a region containing at least any one of an outer side and an inner side of the sub-cone. Each of the linear thin portions has both of a component in a radial direction and a component in a circumferential direction of the sub-cone. The linear thin portion and the linear thin portion cross each other at an intersection. With this configuration, stiffness of the whole sub-cone is reduced to enhance a divided vibration of the sub-cone. In particular, a vibrational displacement of an outer peripheral portion of the sub-cone, from which a sound is mainly radiated, is increased.