Abstract: An unevenness correction data generation device suppressing the appearance of color unevenness when turning on R, G and B together includes a pattern generation unit causing red, green and blue images, in which display panel subpixels are turned on at the same gray level, to be displayed, a monochrome camera, a control unit generating first red, green and blue luminance correction data based on shooting data of the monochrome camera, a pattern generation unit causing the display panel to display a white image by causing red, green and blue images corrected with the respective luminance correction data to be displayed simultaneously, a color camera shooting the white image in color, and a control unit generating color correction data for correcting color unevenness based on shooting data of the color camera and generates unevenness correction data based on the red, green and blue luminance correction data and the color correction data.

Abstract: An impeder for use in an apparatus for resistance tube welding by which a strip-shaped skelp continuously formed into a tubular or spirally tubular shape having spaced opposed edge portions defining a gap therebetween has the edge portions heated and pressed together for being welded. The impeder has a generally tubular casing and a core within the casing consisting of a plurality of laminated bodies each consisting of a plurality of substantially flat planar foils of metallic magnetic material, the core, when viewed in cross-section traverse to the central longitudinal axis of the casing, having the transverse cross-sections of the laminated bodies on parts of at least one circle concentric with the longitudinal axis of the casing and having the planes of the foils extending substantially radially outwardly from the longitudinal axis.