IMAGE FORMING DEVICE

FIELD: physics.SUBSTANCE: image forming apparatus comprises a movable endless intermediate transfer belt, a plurality of support rollers including a first support roller and a second support roller for supporting mentioned intermediate transfer belt, a first to fourth photosensitive drums that are positioned along mentioned intermediate transfer belt between the first support roller and second support roller in the following order: mentioned first photosensitive drum, mentioned second photosensitive drum, mentioned third photosensitive drum, and mentioned fourth photosensitive drum from the downstream side towards the downstream side with respect to the direction in which mentioned intermediate transfer belt moves, and wherein the powder images transferred from mentioned first, second, third and fourth photosensitive drums to mentioned intermediate transfer belt in mentioned first, second, third and fourth primary transfer regions, respectively, are transferred from mentioned intermediate transfer belt to the recording material in the secondary transfer region, and wherein the first to fourth primary transfer regions are located in an imaginary region, limited The assumed position of mentioned intermediate transfer belt tensioned by the first support roller and the second support roller in the hypothetical case in which mentioned first to fourth photosensitive drums are not provided, a constant voltage element that is electrically connected between mentioned intermediate transfer belt and the Earth potential and which is supported specified voltage by passing current through it, voltage source adapted to apply a voltage to the transfer member for transferring a powder image from mentioned intermediate transfer belt to a recording material in order to thereby transmit current through mentioned constant voltage element to form a secondary transfer electric field in the secondary transfer region and a primary transfer electric field In the first to fourth portions of the primary transfer and the clamping member provided in contact with the inner peripheral surface of the beforementioned intermediate transfer belt between the second primary transfer region and the third primary transfer portion configured to clamp mentioned intermediate transfer belt from the inner peripheral surface toward the outer peripheral surface of mentioned intermediate transfer belt.EFFECT: allows to reduce the height of the device to a low level while providing the contact length at