ditolyl 4 4 u2032 biphenyldiamine tpd or tri p tolylamine tta or hydrazones such as n n diethylaminobenzaldehyde 1 1 diphenylhydrazone deh in a typical case two photoconductor drums containing the same formulation were used for analysis initial photo induced decay pid was measured by charging the drum using a charge roll and measuring the discharge voltage as a function of laser energy using a 780 nm laser the pid was obtained as a plot of negative photoconductor voltage u2212 v against laser energy u03bcj cm 2 a duplicate drum was exposed to fluorescent light for about 20 minutes to about 60 minutes and the pid measured immediately in some cases the drums were electrically cycled by repeated charge discharge for 1000 cycles 1 k and the pid measured followed by the measurement of the dark decay dark decay corresponds to the charge lost as a function of time and is represented as v sec in order to evaluate the extent of recovery from the room light exposure the drums were stored in a black plastic bag and a pid curve was obtained after the required recovery time frame the recovery of the photoconductor drum was then compared to the initial charge discharge voltages and the difference corresponds to the fatigue induced in the photoconductor drum due to room light positive fatigue corresponds to photoconductor drums that discharge at lower voltages either on exposure to room light or on cycling repeated charge discharge cycles the drums i e if a drum discharges to u2212 200v and discharges to u2212 150v either on cycling or on exposure to.