Abstract: An image-forming machine having a photosensitive drum disposed in the machine housing, a movable mounting plate disposed in the machine housing so as to be moved toward, and away from, the photosensitive material drum, a developing device detachably mounted on the movable mounting plate from the front side of the machine housing, and a push-operation mechanism for moving the developing device and the movable mounting plate between a push position close to the photosensitive material drum and a push-release position moved away from the push position.

Abstract: A fixing device for an image forming apparatus comprising a heat roller including a hollow roller body and a heater mounted through the roller body. The heater has a plurality of heating portions arranged at equal intervals along the axis thereof. The heater is shifted in the direction opposite to an air flow generated by an exhaust fan with respect to a recording-sheet contact area of the roller body so as to heat the end portion of the roller body located upstream of the air flow sufficiently enough to compensate for the drop of the temperature at the end portion of the recording-sheet contact area located upstream of the air flow cooled below a predetermined temperature by the unheated air flow.

Abstract: A copying machine including an openable original cover, an original holder movably provided on the top of the main body of the copying machine, a locking mechanism provided in the main body of the copying machine and having a projectable lock lever for restricting the movement of the original holder by engaging the receiving parts of the original holder when the original holder is located at a predetermined position, and an ON-OFF detection mechanism for elevating the lock lever a predetermined amount in accordance with the opening and shutting movement of the original cover when the original holder is located at the predetermined position and actuating a switch for driving the detecting means of the original size.