1501927-A is referenced by 17 patents.
1501927 Vacuum cleaners W. J. BATES 26 Aug 1976 [30 May 1975] 23569/75 Heading A4F [Also in Divisions B1 and F4] A vacuum cleaner, e.g. for use in hospitals, comprises a dust bag 4 for collecting dust particles, an electrostatic precipitator, preferably downstream of the dust bag, for removing small particles e.g. bacteria and spores, the precipitator comprising corona producing means 10 for ionizing the small particles and electrodes 12 downstream of the corona producing means for attracting and collecting them, and a fan 6 for drawing air through the dust bag and the precipitator. The fan 6 may be positioned between the dust bag 4 and the electrostatic precipitator or, as shown, at the outlet of the cleaner. If the fan is a tangential fan whose speed can be controlled by a thyristor, the cleaner can also be operated as an air purifier.; Sponge or cellulose fibre filters (e.g. of the Absolute filter type) 8 may be positioned upstream and/or downstream of the electrostatic precipitator. An activated charcoal filter (not shown) may be provided to absorb gases and fumes. Immediately before the air leaves the cleaner there may be an ionizer producing negative ions which are said to be benificial to health.