Ricoh Company, Ltd.

Koichi Asakura

Eiichi Katoh

Yutaka Hasegawa

Toshiro Bando

Tsunehide Takahashi

Hitoshi Hoshi

A control device for a copier is disclosure which detects an error of a drive system and which drives a photoconductive element. The device includes a motor and uses an output of a toner sensor responsive to the density of a toner image which is formed on the photoconductive element. The control device checks the drive system for an error by computing output data of the toner sensor appearing when the photoconductive element is rotated by the drive system and when it is held in a halted mode.

Control device for an image forming apparatus

A controller for controlling a bias power source associated with, for example, a developing unit of an electrophotographic copier such that a bias voltage to be applied to the developing unit for the adjustment of image density is variable in level. The controller includes a central processing unit in which a timer/event counter is built in for delivering a trigger pulse signal to trigger the power source. In order to produce a bias voltage associated with a desired density level, the trigger pulse signal is subjected to pulse width modulation control at a period which is far shorter than an output time consant of the power source.

Bias power source controller for an image forming apparatus

A document size detecting apparatus for a copier and others is disclosed which is capable of identifying the size of a document by use of photosensors the numbers of which is smaller than that of the kinds of documents. A scanner is loaded with a pair of photosensors, or light-sensitive elements, which are spaced from each other in a direction perpendicular to a direction in which a scanner scans a document, the photosensors sensing light which is reflected by a document. A length of a document is determined based on a distance travelled by the scanner from a document scanning start position which is in turn calculated based on a light sensing condition of one of the photosensors, while a width of the document is determined based on a light sensing condition of the other photosensor. Even if a document is placed aslant or in any other dislocated position on a glass platen, its size is identified accurately by positioning the photosensor, which is adapted for the detection of a width, offset relative to a direction which is perpendicular to a scanning direction, or by causing the two photosensors to sense at different timings, or by causing each photosensor to sense twice and deciding outputs of the photosensors valid only when the sensed conditions of the photosensors are identical individually.

Growing community of inventors

Tokyo, Japan

Koichi Asakura