Abstract: The invention intends to reduce a frequency at which defects occur in a welding region during friction stir welding, and to improve the reliability of the welding region. The invention resides in a friction stir welding apparatus wherein a distance to the surfaces of the workpieces is detected by a detector, a change of the detected distance is found by a signal processing device, and a tool is rotated by a rotation driving device in a state where a vertical driving device is controlled by a control device so as to suppress the found change, whereby a plastic fluidity of the workpieces is caused to accomplish joining of the workpieces.

Abstract: The invention intends to reduce a frequency at which defects occur in a welding region during friction stir welding, and to improve the reliability of the welding region. The invention resides in a friction stir welding apparatus wherein a distance to the surfaces of the workpieces is detected by a detector, a change of the detected distance is found by a signal processing device, and a tool is rotated by a rotation driving device in a state where a vertical driving device is controlled by a control device so as to suppress the found change, whereby a plastic fluidity of the workpieces is caused to accomplish joining of the workpieces.

Abstract: The invention intends to reduce a frequency at which defects occur in a welding region during friction stir welding, and to improve the reliability of the welding region. The invention resides in a friction stir welding apparatus wherein a distance to the surfaces of the workpieces is detected by a detector, a change of the detected distance is found by a signal processing device, and a tool is rotated by a rotation driving device in a state where a vertical driving device is controlled by a control device so as to suppress the found change, whereby a plastic fluidity of the workpieces is caused to accomplish joining of the workpieces.

Abstract: A thermal head which comprises an electrically insulating substrate, a glaze layer laid thereon, a heating resistor layer laid on the glaze layer, a plurality of first layer conductors laid on the heating resistor layer and provided at predetermined distances, a protective film laid on the heating resistor layer, and a plurality of second layer conductors counterposed to the first layer conductors and laid on the first layer conductors through an interlayer insulating film, where the interlayer insulating layer is in a two layer structure of an inorganic insulating material layer having a compressive stress and an organic insulating material layer, and the organic insulating material layer is positioned on the second layer conductor side. The thermal head as structured above is free from a problem of crack formation on the interlayer insulating layer, causing a short circuit and free from a problem of discontinuation of the second layer conductors.