Abstract: Toner powders for developing electrostatic images are provided with improved control of the polarity and the color of the particles by forming them of thermoplastic resin containing in dissolved state therein a normal salt of an organic basic dye, e.g. a Safranine dye, and an organic acid, e.g. a phenoxy acetic acid, having at least 6 carbon atoms and having a dissociation constant less then 4 as measured in water at 25.degree.C.

Abstract: Images of fusible toner particles on flexible sheet material, such as applied to paper sheets in electrostatic photocopying machines, are fixed to the material by feeding it through a heating zone in which the particles are softened without fusing them and then passing the material through the nip between smooth rigid pressure roller surfaces which are constantly pressed together under a force sufficiently great to join the heated toner particles superficially one to another and to the sheet structure without forming them into brittle resinous films. An apparatus for carrying out the fixing comprises a set of smooth rigid feed rollers constantly pressed together, preferably by structures like those used for the pressure rollers, under a selected pressure suited for advancing the material into and through a radiant heating zone at a constant speed and thence into the nip of the pressure rollers which are driven at the same peripheral speed.

Abstract: A photocopying apparatus utilizing an exposure plate on which an original pressed image-side downward is exposed to give a reflex image by light from sources disposed laterally below that plate, is caused to give sharper reflex images of transparent originals by the provision of a transparent layer placed over the original, whereby the edge shadows of opaque image portions of the original are broadened and produce displaced reflection areas of reduced intensity. The transparent layer preferably has a thickness of at least 5 mm., and a roughened, translucent surface contacting the original. It may be a frosted glass plate serving also to press the original against the exposure plate.

Abstract: Electrophotographic sheet material comprising a dye-sensitized photoconductive layer is made resistant to fading of its light-sensitivity by incorporating in the photoconductive layer a nitro-substituted xanthene dye, e.g. safrosin.

Abstract: An improved apparatus is provided for developing an electrostatic charge image on a support being moved through a magnetic brush-forming field between a permanent magnet and a rotating cylinder that transports a powder mixture of toner particles and magnetizable carrier particles into said field from a supply of the mixture held in a tray. A wall of the tray bordering the path of the mixture on the cylinder is formed with an edge over which an excess of powder escapes instead of accumulating objectionably in a region between the support and the cylinder. As toner becomes deficient in the tray it is replenished by fresh powder mixture properly proportioned for use, which mixture is supplied into a shorter part of a trough that also receives the powder returned down the cylinder from the magnetic brush region.

Abstract: For fixing electrostatically formed images of thermoplastic powder on copy sheets, an elastic roller and a heated rigid roller form a nip through which each sheet is passed with its image side engaged by the elastic roller, and the elastic roller has a pliable annular body formed with circumferential surface grooves or ribs which cooperate with organs of complementary form for separating each sheet from the roller surface behind the nip, yet which provide an even roller surface in the nip by being elastically deformed therein. The rigid roller is formed with circumferential surface grooves which also cooperate with complementary sheet separating organs. The separating organs cooperating with grooves may be blades extending into them behind the nip, or wires extending in them through the nip; those cooperating with ribs may be blades having profiled edges held almost in contact with ribbed regions of the elastic roller surface.

Abstract: Reproduction elements coated with organic photoconductors are made with improved and/or more widely selectable electrophotographic properties by employing in the photoconductive coating a donor-acceptor complex composed of a known organic electron donor having photo- or semiconductor properties, e.g. a poly-N-vinylcarbazole or polyvinylpyrene, and a N-(fluoren-9-ylidene)-aniline compound as an activating electron acceptor. Especially effective as the electron acceptor are certain new compounds, namely, p- and m-nitro-N-(2,4,7-trinitrofluoren-9-ylidene)-aniline and p-methylsulfonyl-N-(2,4,7-trinitrofluoren-9-ylidene)-aniline.