Abstract: A toner density control method and apparatus of a copying device for copying continuously from a plurality of documents onto recording sheets optically detect the density of a patch image of a reference density plate formed on the surface of a photosensitive drum of the copying device so as to control the toner density. The patch image is formed prior to formation of an image of a first one of a plurality of the documents, the density of the patch image is detected, and a toner replenishment amount during a copying operation of the plurality of documents is maintained constant on the basis of the detected density.

Abstract: A toner density control apparatus wherein an image density of a reference image on a photosensitive member is compared with a predetermined level to control a toner density, a voltage to be applied on a light-emitting element is controlled according to a difference between an output of a light-receiving element when it receives a light reflected from a non-image surface region on the photosensitive member and correction reference data, and a signal is supplied to the outside when the voltage is increased more than a predetermined value.

Abstract: A recording apparatus includes an electrostatic image support and a fixing device. The toner image formed on the electrostatic image support is transferred onto a copy paper, and the copy paper is separated from the surface of the electrostatic image support and then fed to the fixing device to fuse the toner image, for example by heat. A device is provided for distinguishing the relation in the length between the distance (A) from the separating position at which the copy paper is separated from the electrostatic image support to the fixing position of the fixing device, and the length (B) of the copy paper in the transport direction. A control device controls the relative circumferential speeds of the electrostatic image support and the copy paper transport apparatus provided inside the fixing device as a function of the distinguished relation between said lengths (A) and (B).

Abstract: In a copying apparatus having a photosensitive member such as a drum, good reproductivity and image density results from applying a proper charging potential to the photosensitive substance on the drum. The optimum charging potential for each drum can be predetermined and a code or indicia representative of such optimum potential may be attached or otherwise appended to the drum. This code is read by a suitable sensor which in turn controls the charging potential applied to the drum.

Abstract: An apparatus for detecting a residual quantity of toner remaining in the supply hopper of a copying machine includes a piezoelectric vibrating element disposed in a wall of the hopper and having a surface normally positioned in contact with toner in the hopper, and an electronic circuit for causing vibration of the element at a predetermined frequency and for detecting changes in operating characteristics of the element as representative of a decrease in the amount of toner in the hopper to operate a warning device.

Abstract: A method of controlling image density in an electrophotographic copying machine includes operating a first detector to measure the density of a blank region on a photosensitive member, operating a second detector to measure the density of a reference toner image formed on a portion of the blank region, comparing the measured densities of the blank region and the reference toner image, and controlling the density of a developed image of an original in accordance with the results of the comparison. An apparatus in accordance with the invention includes a pair of optical density detecting sensors positioned in opposition to the photosensitive member and in juxtaposition to each other in the direction transverse to the direction of movement of the member.

Abstract: Apparatus for controlling the density of a reproduced image of an original to be copied in an electrophotographic copying machine by maintaining a fixed, predetermined image-developing bias voltage during development of a reference patch image and controlling the bias voltage in response to settings of image density selectors during the development of the original image.

Abstract: An apparatus for controlling the toner concentration in electrophotographic copying machines produces a toner concentration signal in response to the density of a reference patch image formed on a moving electrophotosensitive medium. The patch image density is detected at a time corresponding to a predetermined extent of movement of the electrophotosensitive medium following receipt of a signal indicating scanning of the original to be copied.