GB573316A - Improvements in electrically heated smoothing irons and the like - Google Patents

Abstract

573,316. Electric smoothing-irons. COLDAIR, Ltd., and COMBEN, W. F. Oct. 8, 1943, No. 16502. [Class 39 (iii)] In order to reduce radio frequency disturbances in electric supply lines of electrically heated devices such as smoothing irons of the type having heating resistances 2, 3 separated by a small gap from an earthed conductor 1 and comprising contacts 6, 7 operated for example thermostatically, these contacts are so connected that they interrupt the circuit through the heating element or part thereof at a point such that a substantial proportion of the impedance of the heating element lies between said point and the supply terminals 4, 5; and electrically conducting plate 8 interposed between the heating element and the earthed conductor 1 is insulated from the latter and from most of the heating element but is connected to the heating element near one of the contacts 6, 7. The heating element is in two parts 2, 3 and each of the twoÀ conducting plates 8, 9 is insulated by a thin mica plate 10 from the earthed conductor 1, which may form the sole-plate of the iron. The plates 8, 9 and a sole-plate 1 form a condenser, which may constitute or form part of a spark-quenching condenser. The heating element is flat and covered by mica sheets, except at the ends where it is connected by a short lead to the conducting plate on which it is placed. Each plate 8, 9 may serve as electrical connecting means between a contact and the heating element, which are connected to spaced points on the plate 8 or 9. The plate 8 located beneath heating element 2 may be connected to contact 7, and the plate 9 to contact 6. The heating elements, plates 8, 9 and earthed conductor may be formed as coaxial cylinders. The inner surface of a cover enclosing the elements may form an earthed conductor. Further condensers, resistances or chokes may be added.