Abstract: An image data storing device for an image forming apparatus having a plurality of line buffers to which image data are written from external equipment and from which the written image data are read to form an image. Selectors selectively cause the individual buffers into a read state, write state, and inoperative state. An image forming signal generator generates an image forming signal during one frame of image forming period. During an image forming period, the selectors condition each of the line buffers for any one of the above-mentioned three different states while, during a non-image forming period, they hold the line buffers in the individual states. This allows the line buffers to start operating under the same conditions whenever an image forming period is reached.

Abstract: An apparatus for converting an analog image signal to a digital image signal based on a reference voltage, includes a counter having a control terminal, for counting a first signal and outputting a counted value in digital form, a D/A converter for converting the counted value to an analog voltage signal served as the reference voltage, an A/D converter for converting the analog image signal to the digital image signal based on the reference voltage generated by the D/A converter, and a comparator for comparing in magnitude the digital image signal and a threshold level used for limiting the magnitude of the digital image signal, thereby outputting a control signal based on the results of comparison. The counter continues to count the first signal until the control signal derived from the comparator is supplied to the control terminal of the counter.

Abstract: An image forming apparatus has a control device for controlling an optical output of a semiconductor laser. An operation of controlling the optical output is started with a timing before an incoming signal which indicates an effective image region in a sub scanning direction of a photosensitive body and responsive to a timing signal (or power check start signal) having a predetermined period.

Abstract: A printer structure relies on a laser modulator operating in response to image data cooperates with a rotary deflector for deflecting the modulated laser onto a recording medium with the rotation of the rotary deflector being controlled by a predetermined signal. A synchronizer receives the deflected laser irradiated from the rotary deflector in the vicinity of the recording medium and the synchronizer outputs a signal which defines a timing which the laser modulator uses to begin modulation. At least three memories are used which are each capable of storing the image data corresponding to one line defined by one deflection of the rotary deflector and a memory control device controls the writing of the image data inputted from an exterior of the printer in one memory means after switching the one memory to a write operation in synchronization with the rotary signal defining the one line.