Abstract: An image forming apparatus includes an image bearing member, a container for containing a developer removed from the image bearing member, a detector for detecting an amount of developer removed from the image bearing member and contained in the container, and a failure detector for detecting a failure of the developer amount detector on the basis of the degree of use of the image bearing member and a detection result of the developer amount detector.

Abstract: A life informing device for a charge body includes a body to be charged, and a charging member for charging the charge body. The charging member is adapted to receive an oscillating voltage and to be in contact with the charge body during the charging operation. Also provided is an informing device for visually or acoustically informing the user whether the charge body reaches the end of the life time thereof, based on an accumulated time of the application time during which the oscillating voltage is applied.

Abstract: While the electric power source is turned on, capacitor 1 is charged to a voltage EO by a direct current constant voltage supplier through transistor 4. When the electric power is disconnected, transistor 4 is switched off to discharge capacitor 1 through resistor R1. When the power source is turned on, the voltage of capacitor 1 is read by A/D converter to be produced and stored in CPU 12 memory. Then transistor 4 is switched on to charge capacitor 1 to the voltage EO. Then transistor 4 is switched off and transistor 5 is switched on to discharge capacitor 1 through resistor R2 and a counter stars. When the voltage of capacitor 1 reduces to the same voltage stored in the memory, transistor 5 is switched off to stop the counter and to obtain the counted value t2. Then transistor 4 is switched on to prepare for the next operation. The time lapse t1 after the power source being turned off is obtained by a formula (R1/R2).times.t2.

Abstract: A color image forming apparatus forms a color image by superposing images of plural colors in plane-sequential manner. In the color image forming apparatus, the amount of aberration between the detection signal for the recording medium for the first color and the horizontal synchronization signal is measured by a counter, and the start timing of image formation of the second and subsequent colors is controlled by a delay device, according to the measured amount of aberration.