Abstract: An image forming apparatus includes a document size detection device, a copy paper feeder carrying a plurality of copy paper sheets having different sizes, a copying device for copying an image of the document onto the fed copy paper sheet, the copying means having a copy magnification changer, a copy paper size selector for selecting a desired copy paper size from the plurality of copy paper sizes, a copy magnification setting device for setting a desired copy magnification, a copy mode selection device for selecting either a manual mode or an automatic mode, and a controller for controlling the copy paper feeder and the copy magnification changer so as to execute the manual mode, the automatic mode. The automatic mode has an automatic document size priority sub-mode and an automatic copy paper size priority sub-mode which are changed by actuating the copy paper size selector.

Abstract: An electrophotographic copying machine and a method of setting a copy magnification. The machine includes a glass plate on which an original sheet is set, an exposure lamp for scanning the original sheet, a photoconductor, first, second and third mirrors for reflecting in turn the light reflected by the original sheet, a lens refracting the light from the third mirror for imaging on the photoconductor, a first moving frame for carrying the exposure lamp and the first mirror, a second moving frame for carrying the second and third mirrors, an inputting device for inputting a copy magnification, a setting device for setting the inputted copy magnification by moving the lens and fourth mirror system, and a driving device for moving the first and second moving frames, when the original sheet is scanned, to keep a fixed optical length from the original sheet to the lens.

Abstract: A control device in an image forming apparatus whose main body is connected to one or more options through two-way serial lines having feeding and receiving lines, can determine whether the main body of the image forming apparatus and each of the options are not connected or not, or the power supply of the option is off or not on the basis of determination whether a signal level on the receiving serial line is a reference level or less or more over a predetermined constant time period if a response signal from the option is not sent back to the main body and correspondingly, can automatically subject the option to suitable control processing.

Abstract: A specific cassette selection apparatus for use with a copying machine having a plurality of removable paper feeding cassettes. The apparatus includes an identification device, a specific copying mode selection device, and a paper feeding cassette selection device. The cassette selection device responds to paper-size identification signals from the identification device and a copying mode selection signal from the mode selection device to select a cassette for use in a selected copying mode. When either a two-sided copying mode or a continuous copying mode is selected, the paper feeding cassette selection device selects a specific paper feeding cassette containing copying paper of only a specific paper size associated with the two-sided copying and/or the continuous copying modes.

Abstract: An automatic exposure device for a photocopying machine. A signal indicative of exposure light intensity and a signal indicative of the received light intensity from an original are obtained by initially exposing two types of original documents the densities of which are different from each other. A proper exposure light intensity is established corresponding to the density of the original document to be copied on the basis of the above-obtained intensities. If the exposure light intensity changes in accordance with the density of an original document and the exposure light intensity to be changed should exceed an upper limit value or be less than a lower limit value, that limit value is established as the proper exposure light density.

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.

Abstract: A toner density control device comprising a toner density sensor to detect the density of the toner contained in the developer stored in a developing device, toner agitating means to agitate the developer stored in the developing device so as to charge the toner with frictional electricity, control standard value holding means which maintains as the control standard value the toner density that is lower by a specified value than that detected by the toner density sensor under a condition where the developer is agitated for some time by the toner agitating means during the initial stage after the developer is supplied into the developing device, and toner replenishment means which actuates under a condition when the toner density detected by the toner density sensor is lower than the control standard value, thereby controlling the toner density in the developing device in accordance with the control standard value maintained in a manner as stated above.