Electrostatic imaging device capable of producing high-quality image despite variations in ambient conditions

Claim 1

An electrostatic imaging device comprising: a photoreceptor drum for carrying thereon a toner layer having an electrostatic latent image; a transcription roller for transcribing said toner layer onto a recording sheet; a power source for providing a transcription voltage and transcription current to said transcription roller; a voltmeter for measuring said transcription voltage; an ammeter for measuring said transcription current; and a ROM for storing a first data for a first characteristic between said transcription voltage and transcription current and a second data for a plurality of second characteristics between said transcription voltage and said transcription current, said power source providing electrical power to said transcription roller based on said first characteristic during an initialization of said transcription roller, said power source selecting one of said second characteristics based on said transcription voltage and said transcription current measured during said initialization period, said power source providing power to said transcription roller during a normal operation of said transcription roller based on said selected one of said second characteristics.

Claim 6

A method for forming an electrostatic latent image on a recording sheet comprising the steps of: applying a first power source having a first characteristic to a transcription roller, said first characteristic being expressed by I/a+V/b=1, wherein I and V represent a transcription current and a transcription voltage, respectively, and "a" and "b" are constants which are larger than zero; measuring said transcription voltage and said transcription current during an initialization period; selecting one of a plurality of second characteristics based on the measured transcription voltage and the measured transcription current; and applying a second power source having said selected one of said second characteristics to said transcription roller during an operational period.

Claim 7

A method for forming an electrostatic latent image on a recording sheet comprising the steps of: applying a first power source having a first characteristic to a transcription roller, said first characteristic being expressed by I/a+V/b=1, wherein I and V represent a transcription current and a transcription voltage, respectively, and "a" and "b" are constants which are larger than zero; measuring said transcription voltage and said transcription current during an initialization period; selecting one of a plurality of second characteristics based on the measured transcription voltage and the measured transcription current; and applying a second power source having said selected one of said second characteristics to said transcription roller during an operational period.