Abstract: A power supply device that applies a voltage in which a direct-current (DC) voltage and an alternating-current (AC) voltage are superimposed on each other to a charging member that charges an image bearer, includes: an AC voltage generation circuit that generates the AC voltage; a DC voltage generation circuit that generates the DC voltage; a DC current detection circuit provided on an output terminal side of the DC voltage generation circuit, which detects an output DC current flowing into the image bearer; and a reduction circuit that reduces an inflow of an AC current to the DC current detection circuit.

Abstract: A thermal development type diazo copying material comprising a support material and a photosensitive layer formed on the support material, which photosensitive layer comprises a diazo compound, a coupling component and a thermo-fusible auxiliary coloring agent, and which coupling component is capsulated by a hydrophobic polymeric material with a softening point ranging from 50.degree. C. to 150.degree. C. selected from the group consisting of hydrophobic polyester resins, hydrophobic cellulose resins, hydrophobic polyamide resins and hydrophobic polyurethane resins.