Electric heating:
This subclass covers not only the electric elements and circuitry designs but also the electric aspects of their arrangement, where these concern cases of general application. Where heating elements are used in specific applications, please see the relevant subclasses.
Electric lighting:
The primary circuits of the above light sources and the elements themselves of the circuits are covered by this subclass. The above light sources when combined with light sources of a different kind are also covered by this subclass.
This subclass is residual for electric lighting.
Uses of electric heat sources, or apparatus incorporating such heat sources, are too numerous to mention and cover all possible areas of technology. Examples of places where such uses or apparatus could be found include A47J (domestic cooking); B21J , B21K (forging by heat); C21 , C22 , C23 (metallurgy); F24 (domestic heating and stoves); F27 (furnaces and ovens). See also the references below.
Uses of electric light sources are also too numerous to mention and cover all possible areas of technology. A comprehensive list of possible places where lighting devices can be found in Note (3) after the title of class F21 .
Class F21 covers the material arrangement of the various electric elements, i.e. their geometrical or physical position in relation to one another, such as the structures or constructional features of lighting devices incorporating a light source, electric or otherwise.
| Regulating electric characteristics of arcs in general | G05F 1/02 |
| Heating or cooling appliances for medical or therapeutic treatment | A61F 7/00 |
| Heating by electric, magnetic or electromagnetic fields for therapeutic purposes | A61N 5/00 |
| Joining of preformed parts by heating of plastics or substances in a plastic state | B29C 65/02 |
| Thermally-actuated switches | H01H 37/00 |
| Electron beam or ion beam tubes for localised treatment of objects | H01J 37/30 |
| Electric discharge tubes | H01J |
| Electric discharge lamps | H01J 61/00-H01J 65/00 |
| Electric incandescent lamps | H01K |
| Semiconductor devices with at least one particular jump barrier or surface barrier, specially adapted for light emission | H01L 27/15 , H01L 33/00 |
| Organic light emitting devices (OLED) | H01L 27/32 , H01L 51/50 |
| Stimulated-emission devices | H01S |
| Plasma torches | H05H 1/26 |
| Measuring of temperature by colorimeter | G01J |
| Control of temperature in general | G05D 23/00 |
| Regulating electric power in general | G05F 1/66 |