Abstract: A defect analysis system for a xerographic print engine includes a residual mass sensor that senses the two-dimensional signature structure of residual mass remaining on a photoconductive or other substrate surface after image transfer. Preferably, the sensor is a full width array that spans substantially an entire width of the photoconductive surface. This information is then processed and analyzed to determine a specific type of transfer defect present. This may include the quantified level of defect for each detected type. The defect analysis system may also include a closed-loop control system that can adjust various xerographic process parameters using feedback based on the identification and optionally magnitude of each specific defect type. The identified print quality defect, such as mottle, streaks, point deletions, graininess, etc.

Abstract: A piezoelectric acoustic transducer, especially for a printer photoreceptor toner transfer assist system, having a mechanical resonance varying over a substantial frequency range, is driven by a driver circuit having an automatically variable frequency electrical power output. The driver circuit initially automatically slowly sweeps over a wide frequency range encompassing the resonance range of the transducer until the resonant frequency is detected from the electrical impedance change of the transducer at resonance. The driver circuit then automatically switches to a frequency control with a phase lock loop system responsive to the phase of the transducer voltage and current, to hold and maintain the driver circuit output at the varying resonant frequency of the transducer. A small frequency range rapid dithering of the driver circuit frequency may be additionally provided above and below the resonant frequency of the transducer.

Abstract: A portable water-purifying device comprises a primary disinfecting chamber (50) and a combined secondary disinfecting chamber and post-filter (30). Water to be purified can be scooped by means of a cover (12) into a receptacle (90) containing a pre-filter media (39) of preferably silvered activated carbon beneath a coarse entry filter pad (102). From that receptacle (90) the water enters the primary disinfecting chamber (50), flowing downwards through nine or so passage-forming segments (22) filled with a microbiocide (56), to effect primary disinfection, that is, to kill a substantial number of pathogenic organisms, but probably not all. Each passage (22) is at least three times longer than it is wide, to prevent channelling of the water through the microbiocide. Disinfectant from the microbiocide (56) enters the water as it passes through.

Abstract: Method and apparatus for providing multiple colors in a single pass of a copy sheet through a transfer station by switching the polarity of a transfer corotron and automatically adjusting the output of the detac corona device. In particular, a single power supply including high voltage switches responds to color selections to change the polarity of a transfer corotron to charge a copy sheet for toner transfer, and a current sense and precision rectifier stage responds to the copy sheet charge to provide a suitable detac charge independent of the transfer corotron polarity.