Abstract: In a method for manufacturing an optical fiber, a dummy rod is connected to a vicinity of an upper end of a glass preform which includes a diameter-reduced portion at an upper portion thereof, and the glass preform is heated to be melt in a drawing furnace to draw an optical fiber. A cap member is provided at a position of the diameter-reduced portion, and an upper end of the cap member is disposed close to a lower end of the dummy rod. When an orthogonal coordinate axis is set, in which an outer diameter ratio of the cap member to the glass preform is set as a horizontal axis x, and an outer diameter ratio of the dummy rod to the glass preform is set as a vertical axis y, the x and the y satisfy an expression y?0.1527×x?3.103.

Abstract: In a method for manufacturing an optical fiber, a dummy rod is connected to a vicinity of an upper end of a glass preform which includes a diameter-reduced portion at an upper portion thereof, and the glass preform is heated to be melt in a drawing furnace to draw an optical fiber. A cap member is provided at a position of the diameter-reduced portion, and an upper end of the cap member is disposed close to a lower end of the dummy rod. When an orthogonal coordinate axis is set, in which an outer diameter ratio of the cap member to the glass preform is set as a horizontal axis x, and an outer diameter ratio of the dummy rod to the glass preform is set as a vertical axis y, the x and the y satisfy an expression y?0.1527×x?3.103.

Abstract: A self-propelled electronic device comprising: a housing; a drive wheel that enables the housing to travel; a wheel drop sensor that detects loss of contact of the drive wheel with a floor surface; and a travel control unit that controls travel of the housing, wherein, when the wheel drop sensor detects loss of contact of the drive wheel with the floor surface, the travel control unit continues travel of the housing for a predetermined continuous travel time, and if the wheel drop sensor still detects loss of contact of the drive wheel with the floor surface after the continuous travel time has elapsed, the travel control unit stops the rotation of the drive wheel, and then, rotates the drive wheel in a direction opposite to the direction of the rotation for a predetermined reverse travel time, to cause the housing to travel in a reverse direction.

Abstract: A self-propelled electronic device comprising; a housing; a drive wheel that enables the housing to travel; a wheel drop sensor that detects loss of contact of the drive wheel with a floor surface; and a travel control unit that controls travel of the housing, wherein, when the wheel drop sensor detects loss of contact of the drive wheel with the floor surface, the travel control unit continues travel of the housing for a predetermined continuous travel time, and if the wheel drop sensor still detects loss of contact of the drive wheel with the floor surface after the continuous travel time has elapsed, the travel control unit stops the rotation of the drive wheel, and then, rotates the drive wheel in a direction opposite to the direction of the rotation for a predetermined reverse travel time, to cause the housing to travel in a reverse direction.