Abstract: A method of cleaning a process tube and a wafer boat, comprising the steps of, carrying wafers out of the process tube, controlling the temperature in the process tube saw as or lower than a process temperature and higher than a boiling point of ClF.sub.3, said process temperature being kept in the process tube when the process of forming film on the wafers is carried out in the process tube, and supplying ClF.sub.3 -contained cleaning gas into the process tube to react the cleaning gas with the film of the silicon oxide adhering to the inner wall of the process tube and the wafer boat.

Abstract: An image processing apparatus for processing an image signal, comprising a clock for generating a periodical clock signal, a pattern signal generator for generating 2N (where N is a positive integer) pattern signals, each of the pattern signals having a constant wave-form, a wave length of 2N times longer than that of the periodical clock signal and a phase difference 360/2N relative to another one of the pattern signals, a comparator for comparing the pattern signals with the image signal and for generating 2N of comparison signals, and a composition generator for combining said 2N comparison signals and for generating a pulse-duration modulated signal from the combined 2N comparison signals.

Abstract: Present invention provides an image forming apparatus capable of forming an image on various kinds of photosensitive material by subjecting the photosensitive material to an image forming process having at least imagewise exposing, developing, and fixing process on a process condition determined in accordance with a kind of the photosensitive material. While processing certain kind of photosensitive material, a kind discriminator detects a new kind of photosensitive material being subjected a current image forming process, CPU inhibits a new image forming process until judging a predetermined process of the current image forming process as being completed from a signal of a process monitor.

Abstract: An image forming apparatus is disclosed, in which silver halide color photographic light-sensitive materials are used. The apparatus has a scanning exposure system and a processing system for the photographic materials. Two types of photographic materials, reflective type and transparent type, can be used interchangeably. Conditions of the exposure and the processing are automatically changed according to the types of the photographic materials.