Abstract: A tin oxide carbon monoxide sensor is operated in a manner to exclude effects of ambient temperature and humidity. Resistance of the sensor is measured at a lower temperature and again at a higher temperature. The target gas concentration is determined as a function of the first and second resistances, thereby cancelling the effects of humidity and ambient temperature.

Abstract: An improved photoconductive surface coating is provided having panchromatic sensitivity and increased resistance against spectral response shift upon reuse of the photoconductive layer. The surface coating comprises zinc oxide particles, a minor amount of a group IIB selenide or telluride and a binder in substantially uniform mixture. The selenide or telluride is present either as discrete particles or chemically deposited on the zinc oxide particles. In the latter instance, the resulting particles exhibit bi-chargeability and substantially increased light sensitivity. The selenide or telluride can be deposited chemically in accordance with one embodiment by dispersing zinc oxide particles in a medium such as water and precipitating the selenide or telluride, preferably in situ, on the surfaces of the particles.

Abstract: An improved photoconductive surface coating is provided having panchromatic sensitivity and increased resistance against spectral response shift upon reuse of the photoconductive layer. The surface coating comprises zinc oxide particles, a minor amount of a group IIB selenide or telluride and a binder in substantially uniform mixture. The selenide or telluride is chemically deposited on the zinc oxide particles. The resulting particles exhibit bi-chargeability and substantially increased light sensitivity. The selenide or telluride can be deposited chemically in accordance with one embodiment by dispersing zinc oxide particles in a medium such an water and precipitating the selenide or telluride, preferably in situ, on the surface of the particles.

Abstract: A thin insulative film is applied to be in direct contact with a surface carrying an electrostatic image which has a potential sufficient for adherence by induction of toner to the insulative film but insufficient to discharge when in contact with or upon separation of the toned insulative film. When the surface is photoconductive, it is exposed before or after contact with the insulative film to a pattern of discharging radiation to form an electrostatic image thereon. As one form of image development, toner is applied to the insulative film while in direct contact with the imaged surface. Thereafter, the toner image may be transferred to a support member. Toning and toner transfer is repeated without further charge and without further exposure.