Abstract: An image forming device for connection to first and second external devices, including a control unit having an alternate operation mode for performing alternating communication with external devices by switching communication at a predetermined cycle. During communication with one of such external devices, the control unit enables reception of commands and/or a print-start signal from that external device and refuses reception of commands and a print-start signal from another external device. When communication is changed over from one external device to another external device, the control unit provides an interval in which reception of commands and a print-start signal from both external devices is refused for a predetermined period of time.

Abstract: An image forming device (2) comprises a first connector (3) and a second connector (4) for connecting a printer engine (1) arranged therein, with a first external device (5) and a second external device (6); and a control unit (7) having an alternate operation mode in which the communications between the first external device (5) and the second external device (6) through the first connector (3) and the second connector (4) are alternately performed in a predetermined cycle.

Abstract: A method for developing an electrostatic latent image comprises the steps of attracting a developer comprised of a magnetic toner and a magnetic carrier onto the surface of a sleeve with a magnet roll disposed therein, rotating the magnet roll and the sleeve in the direction opposite to the rotational direction of an image carrier to move the developer in the same direction as the sleeve, and supplying the developer onto the image carrier under an alternating electrical field and an alternating magnetic field to thereby conduct development. An apparatus for effecting the method comprises a casing for accommodating the developer; the magnet roll arranged to be rotated in the direction opposite to the rotational direction of image carrier; the sleeve arranged to be rotated in the same direction as the magnet roll; and an alternating electrical field applying means.