Abstract: An image forming apparatus includes a laser beam scanning unit for scanning a recording medium in synchronism with a writing clock signal so that a dotted image is formed on the recording medium, a counter for carrying out a count operation in synchronism with the writing clock signal so that one count value or a plurality of count values determining a scanning area is/are obtained, a first controller for activating or inactivating the laser beam scanning unit based on one or the plurality of count values, a dip switch unit for specifying a dotting density, a second controller for controlling the frequency of the writing clock signal and/or a speed of scanning; and a changing unit for changing one or the plurality of count values, which should be obtained by the counter, based on the dotting density specified by the dip switch unit, so that the position of the scanning area with respect to the recording medium is constant even if the frequency of the writing clock signal and/or the scanning speed are changed

Abstract: A modular type image forming system includes a laser printer main unit and a plurality of optional units, such as a both side processing unit, a large quantity paper feeding unit and a mail box unit, each of which is operatively coupled to said main unit through a commonly usable optical fiber cable through a commonly usable connector. Each unit has its own CPU and serial communications between the CPUs of different units may be carried out through the optical cables. The CPU of the main unit may determine the identity of each of the optional units connected thereto through such communications. The main unit also includes an interface circuit through which the main unit is operatively coupled to each of the optional units. The interface circuit includes a port selector which establishes a connection pattern between the main and optional units in accordance with the identity information of each of the optional units connected.

Abstract: An image forming apparatus is provided with sensors for detecting existence of sheets of paper at a plurality of positions in transport paths within the image forming apparatus. A circuit part counts a number of sheets of paper remaining within the image forming apparatus when a transport abnormality occurs based on outputs of the sensors. This number of sheets of paper remaining within the image forming apparatus when the transport abnormality occurs is displayed on a display.

Abstract: A sheet transport apparatus is used in a duplex image forming apparatus which makes two-sided prints. The sheet transport apparatus has a transport path for supplying a recording sheet which is received from a paper supplying unit to an image forming part, a reversing path for reversing side of the recording sheet, and two driving sources for independently driving mechanisms which transport the recording sheet in each of the transport path and the reversing path.

Abstract: A modular type image forming system includes a laser printer main unit and a plurality of optional units, such as both side processing unit, a large quantity paper feeding unit and a mail box unit, each of which is operatively coupled to said main unit through a commonly usable optical fiber cable through a commonly usable connector. Each unit has its own CPU and serial communications between the CPUs of different units may be carried out through the optical cables. The CPU of the main unit may determine the identity of each of the optional units connected thereto through such communications. The main unit also includes an interface circuit through which the main unit is operatively coupled to each of the optional units. The interface circuit includes a port selector which establishes a connection pattern between the main and optional units in accordance with the identity information of each of the optional units connected.

Abstract: An image forming system comprises one or a plurality of image forming apparatuses and a host system coupled thereto. Each image forming apparatus is provided with a control part for reading out status information on the image forming apparatus at an arbitrary time. The obtained status information may be displayed or printed at the image forming apparatus and/or supplied to the host system.

Abstract: A control system for a laser printer and other image recorders stores history data including the number of prints produced by a photoconductive element and occurrences of various kinds of failures, and displays the history data at suitable timings. The control system, therefore, displays data which may be referenced in the event of a failure of the image recorder.