US Patent 7283144 Heat developing apparatus and heat developing method

This heat developing method includes a step of forming a latent image on a heat developing photosensitive film sheet and a step of developing the film sheet, while the film sheet on which a latent image is formed is being conveyed, by heating with segmented heaters which are formed by dividing the total heating area into plural segments in the direction perpendicular to the conveyance direction, and which are independently temperature controllable, wherein the film sheet is so conveyed that no film sheets of different sizes are simultaneously in contact with any segmented heater.