Abstract: An air purifier includes a cabinet, an electrically driven fan, a replaceable filter element, and an air quality sensor. A display provides a visual indication of the air quality condition. A microprocessor is programmed to control the speed of the fan automatically according to the air quality condition. The microprocessor also computes when the filter element must be changed by totalling the time of operation and its speed (which equals air quality) so that for example the filter element will be changed more often (used for less aggregate time) when the air purifier is operated in a poor quality environment.

Abstract: An air purifier comprises a cabinet an electrically driven fan a replaceable filter element and an air quality sensor A display provides a visual indication of the air quality condition. A microprocessor is programmed to control the speed of the fan automatically according to the air quality condition. The microprocessor also computes when the filter element must be changed by totalling the time of operation and its speed (which equals air quality) so that for example the filter element will be changed more often (used for less aggregate time) when the air purifier is operated in a poor quality environment.

Abstract: In an otherwise well-known electric pop-up toaster, an auxiliary power switch is provided and is arranged to be opened by a timer after each toasting cycle. This ensures, in contrast to the well-known toaster arrangements, that power is interrupted to heating elements even if a carriage supporting slices of toast fails to move up at the end of a toasting cycle.

Abstract: In an otherwise well-known electric pop-up toaster, an auxiliary power switch is provided and is arranged to be opened by a timer after each toasting cycle. This ensures, in contrast to the well-known toaster arrangements, that power is interrupted to heating elements even if a carriage supporting slices of toast fails to move up at the end of a toasting cycle.