Whole Body Computed Tomography

A screen printing machine comprising a transporting mechanism supporting thereon a material to be printed for transporting the material continuously or intermittently to a printing operation zone is disclosed in which a lifting device is used to bring the material to be printed into contact with a screen and a squeegee member. The printing machine includes a screen disposed in the printing operation zone above a running passage for the material to be printed and a squeegee member disposed to squeeze out a printing paste or ink through the screen onto the material to be printed. The lifting device causes the material to be printed to be lifted and brings it into contact with the screen during the printing step and lowers and separates the material from the screen during the non-printing period by moving the transporting mechanism supporting the material to be printed vertically downward and away from the screen and/or moving the screen and squeegee vertically upward and away from the transporting mechanism supporting the material to be printed. The lifting device includes a partially toothed driving wheel, a partially toothed lifting wheel, and a lifting cam integral with the partially toothed lifting wheel. The partially toothed driving wheel and the partially toothed lifting wheel are engaged with each other inermittently and synchronously so that by the engagement between the two partially toothed wheels the lifting member is caused to move vertically upward or downward and by release of the engagement between the two partially toothed wheels the lifting member is restrained at the elevated or lowered position.