Patent ID: 7937001

Claim:
An image forming apparatus for printing color images comprising: an image forming controller for accessing first to Nth (N is a positive integer greater than 1) developing units; first to Nth mounting slots to receive the first to Nth developing units, the first to Nth mounting slots including a first mounting slot non-movably installed in the image forming apparatus to receive the first developing unit at a first mounting location, a second mounting slot non-movably installed in the image forming apparatus to receive the second developing unit at a second mounting location, a third mounting slot non-movably installed in the image forming apparatus to receive the third developing unit at a third mounting location and a fourth mounting slot non-movably installed in the image forming apparatus to receive the fourth developing unit at a fourth mounting location; a switching unit coupled between the image forming controller and the mounting slots for performing a switching operation in accordance with a switching signal; first to Nth clock signal lines for delivering clock signals from the switching unit to the first to Nth mounting slots, the first to Nth clock signal lines including a first clock signal line coupled between the switching unit and the first mounting slot, a second clock signal line coupled between the switching unit and the second mounting slot, a third clock signal line coupled between the switching unit and the third mounting slot, and a fourth clock signal line coupled between the switching unit and the fourth mounting slot; and a data line for connecting the image forming controller to the first to Nth mounting slots; wherein the switching unit performs the switching operation in accordance with switching signal such that one of the clock signals is transmitted to one of the mounting slots corresponding to the switching signal without transmitting the respective clock signal to the remaining mounting slots; and wherein the image forming controller determines whether a developing unit associated with a proper color is mounted on one of the mounting slots corresponding to the switching signal based on a signal received from one of the mountings via the data line.