JP-A-2000-112302 and JP-A-2003-316128 disclose an image forming apparatus which detects abnormality produced in a charger.
The image forming apparatus disclosed in JP-A-2000-112302 1 includes one photosensitive member which is charged in the image forming time and transfers a toner image onto a paper sheet. In this image forming apparatus, a charge-side leak detection circuit is provided on an output side of a high-voltage power supply part connected to a primary charger, which charges the photosensitive member uniformly at a predetermined potential. The charge-side leak detection circuit detects occurrence of leak. Further, a static eliminator-side leak detecting circuit is provided on an output side of a high-voltage power supply part connected to a separation static eliminator, which eliminates transfer electric charge on the back surface of a paper sheet thereby to separate the paper sheet attached on the photosensitive member from the photosensitive member. The static eliminator-side leak detecting circuit detects occurrence of leak.
The image forming apparatus disclosed in JP-A-2003-316128 includes four high-voltage power supply parts and four chargers correspondingly to photosensitive drums of four colors. Each high-voltage power supply part is provided with a leak detection circuit which detects leak of charging bias.