Abstract: There is described a multi-layer printed circuit board and a method of installing it. The circuit board includes a first signal layer formed on its obverse surface; a ground layer arranged at a position next to the first signal layer; an electronic power source layer arranged at a position next to the ground layer; and a second signal layer formed on its reverse surface. The first and second patterns are formed around peripheral areas of the first and second signal layers, respectively. The first ground pattern and the second ground pattern are electrically coupled to each other by plural through holes, and the multi-layer printed circuit board is installed on an electro-conductive housing in such a manner that a substantially whole area of the second ground pattern electrically contacts a mounting area of the electro-conductive housing, the mounting area being an electro-conductive area continuously coupled to the electro-conductive housing.

Abstract: There is described a multi-layer printed circuit board and a method of installing it. The circuit board includes a first signal layer formed on its obverse surface; a ground layer arranged at a position next to the first signal layer; an electronic power source layer arranged at a position next to the ground layer; and a second signal layer formed on its reverse surface. The first and second patterns are formed around peripheral areas of the first and second signal layers, respectively. The first ground pattern and the second ground pattern are electrically coupled to each other by plural through holes, and the multi-layer printed circuit board is installed on an electro-conductive housing in such a manner that a substantially whole area of the second ground pattern electrically contacts a mounting area of the electro-conductive housing, the mounting area being an electro-conductive area continuously coupled to the electro-conductive housing.

Abstract: An electronic device having a printed circuit board having a ground, an electrically insulating layer provided on a face of the printed circuit board, and an electromagnetic shielding layer adhered to the face of the printed circuit board through the electrically insulating layer. The ground of the printed circuit board and the electromagnetic shielding layer are conducted electrically.

Abstract: An electronic device having a printed circuit board having a ground, an electrically insulating layer provided on a face of the printed circuit board, and an electromagnetic shielding layer adhered to the face of the printed circuit board through the electrically insulating layer. The ground of the printed circuit board and the electromagnetic shielding layer are conducted electrically.

Abstract: A fixing unit for printers or copiers includes a heater, in the fixing unit, for heating a fixing member to fix a toner image on a sheet; a zero-cross detector for detecting zero-cross timings of electric power when a voltage of the electric power is at zero volts; a switching circuit for turning on and off the electric power to the heater; a controller for controlling the switching operation of the circuit so as to provide a first state in which the electric power is continuously supplied to the heater for a second state in which the electric power is not supplied to the heater for a multiple of half-cycles from one of the zero cross timings. In the fixing unit, the electric power is supplied to the heater with an intermittent pattern, including the second state, for a predetermined period after at least one of a turn-on operation of the heater and a turn-off operation of the heater.

Abstract: In a color image forming apparatus, an image retainer, a charger, a plurality of developing devices and a cleaner are made in one unit. The unit is dismountably supported in a housing so that the unit can be moved out from a first position at which the unit is set in the housing to a second position at which jam disposition is conducted. When the unit means is placed at the second position, a part of the apparatus is used to cover the image retaining surface at the transfer section.

Abstract: An image processing apparatus for processing a digital color signal, given from outside the image processing apparatus, into a digital color recording signal, comprising; a color code generator for generating a color code signal representing a color of a digital pixel image signal, and a color reproduction unit for generating a color recording signal by processing another digital pixel image signal, in which these two digital pixel image signals are processed separately.

Abstract: A color image processing apparatus comprises an image reading circuit for reading an original image as three color-separated images, a color code generating circuit for generating a color code indicating whether each pixel of the original image is white, black, or chromatic, a color reproducing circuit for generating density data for each pixel corresponding to each of a plurality of recording colors based on the color-separated images, a marker area detecting circuit for detecting a marker on the original image based on the color code generated by the color code generating circuit and for extracting a marker area enclosed by the marker, a density data sampling circuit for sampling density data of pixels on the marker at a sampling point located at a selected distance, corresponding to a predetermined number of pixels, inside of the edge of the marker, and for determining a density data of the marker based on the sample density data, and a density data conversion circuit for converting the density data of pix

Abstract: A color image processing apparatus wherein a document image is divided into three colors and converted the color separated images into density data that correspond to a recording color by a color reproducing device. The color reproducing device has matrix coefficients for a plurality of linear maskings, a linear masking is selected out of the plurality of linear maskings by the three color separation signals, the linear masking is carried out using the masking coefficients of the selected linear masking, and the color separated images are converted into density data that correspond to the recording color.

Abstract: An image processing apparatus for processing an image signal, comprising a clock for generating a periodical clock signal, a pattern signal generator for generating 2N (where N is a positive integer) pattern signals, each of the pattern signals having a constant wave-form, a wave length of 2N times longer than that of the periodical clock signal and a phase difference 360/2N relative to another one of the pattern signals, a comparator for comparing the pattern signals with the image signal and for generating 2N of comparison signals, and a composition generator for combining said 2N comparison signals and for generating a pulse-duration modulated signal from the combined 2N comparison signals.

Abstract: A method of cleaning an image retainer by removing remaining toner particles from the retainer after transferring a multi-color toner image which is obtained by a multi-color toner image forming process wherein charging, image writing-in, and developing steps are repeated at least twice, abutting a cleaning member against the retainer after a final image writing-in step of the image forming process has been completed, and releasing the cleaning member from abutment after the cleaning has been completed but not during the image writing-in step for forming a next multi-color toner image.

Abstract: A color image forming apparatus wherein a color image is formed by rotating plural times an image retainer and repeating a latent image formation and a development. The start timing of an image forming cycle is controlled by using one of reference signals corresponding to one of a plurality of predetermined positions on the image retainer and the start timing of another image forming cycle is controlled by using another of the reference signal.

Abstract: In a color image processing apparatus according to the invention, a color image signal being photoelectrically obtained by a image reader is separated into red, blue and black color component signals. A laser scanner writes respective latent images corresponding to the color component signals on a cylindrical photoreceptor. Each of the respective latent images are written during one rotation of the photoreceptor. The initial writing positions of the respective latent images are registered by using a drum index signal generated in synchronization with the rotation of the photoreceptor. An optical output starts outputting an optical signal in response to the index signal or an encoder signal selected according to the copy mode.

Abstract: An image recording apparatus wherein image information is developed by converting the image information into an optical signal and by writing the image information on a drum-shaped image retainer with the converted optical signal to provide latent images and by developing the latent images, which are then recorded. A first writing timing is set in a first writing direction with respect to the image retainer and a second writing timing is set in a second writing direction with respect to the image retainer and the number of rotations with respect to the image retainer is calculated in accordance with the settings of the writing timings. The image information is overwritten by a number of times corresponding to the number of rotations to provide a plurality of images which may be entirely or partially or not superposed on one another.

Abstract: An image forming apparatus for conducting writing and developing operations several times on an image retainer and transferring the developed images to a transfer material. An output of a developing bias power source is sequentially distributed to a plurality of developing devices in the order in which the image retainer moves from an image signal writing device and the beginning of the abutment of a cleaning member against the image retainer and the beginning of the release from the abutment fall at timing other than at least the image writing timing.

Abstract: The apparatus includes a vertically movable paper tray that descends to its lowered condition when a copier door is opened for resupply of copy sheets, a switch for detecting the fully raised sheet feeding condition of the tray, and a photosensor for detecting the presence of paper on the tray as the tray is raised toward its fully raised condition. A copier operation enabling signal is generated in response to the position of the door and the photosensor output, with a suitable time delay to prevent copying until the tray has attained its fully raised condition following detection of the presence of paper by the photosensor.