| 摘要 |
PROBLEM TO BE SOLVED: To control the recovery and the discharge of a remaining toner after transfer in a contact electrifying member and to stably maintain a high-quality image output over a long term by providing a contact electrifying means for electrifying an image carrier by bringing the electrifying member on which a voltage is impressed into contact with the image carrier and by using a voltage obtained by superposing an alternating voltage on a DC voltage as a voltage impressed on the electrifying member to specify the value of the alternating voltage. SOLUTION: A contact electrifying means electrifies an image carrier by bringing an electrifying member into contact with the image carrier. A voltage impressed on the electrifying member is a voltage obtained by superposing an alternating voltage on a DC voltage and the alternating voltage satisfies the conditions (a) and (b) at the time of forming an image. The (a) is Vup >Vdown (Tup <Tdown ) and the (b) is VUP×TUP=Vdown ×TDOWN. The Vup is an electrification polarity direction side component of the alternating voltage and is the mean value of a potential difference between the component and an electrifying DC component, the Tup is the rate of the impressed time of the electrification polarity direction side component of the alternating voltage, the Vdown is an electrification polarity reverse direction side component of the alternating voltage and is the mean value of a potential difference between the component and the electrifying DC component and the Tdown is the rate of the impressed time of the electrification polarity reverse direction side component of the alternating voltage. |
