Iwatsu Electric Company Ltd.

Yousuke Igarashi

Minehiro Sakata

Masanori Kai

Tamio Iwamoto

Satoshi Hisabayashi

Takeo Kadoi

Masahiro Kogiso

Yasuyuki Yokoyama

Youji Koganei

Ikuo Ota

Satoshi Hisabayoshi

Yoshio Horiguchi

Shuichi Kudo

Seiichi Honma

Seiichi Homma

A method of controlling a position of a plate material sheet in a platemaking machine for feeding the plate material sheet in an exposure region and forming a document image on the plate material sheet. A plate material sheet length sensor detects that the plate material sheet to be fed to the exposure region has passed by the sensor. The overall length of the plate material sheet is calculated in accordance with the number of pulses supplied to a plate material sheet drive motor while the plate material sheet length sensor generates an output. Also calculated is a first predetermined number of pulses to be supplied to the plate material sheet drive motor so as to feed the plate material sheet by a first predetermined length within the exposure region. A stop sensor detects a front edge of the plate material sheet, the stop sensor being arranged such that a center thereof is aligned with the axis of the optical system; and the first predetermined number of pulses is supplied to the plate material sheet drive motor after the stop sensor generates an output, so that a center of a first portion of the plate material sheet is aligned with the axis of the optical system.

Method of controlling platemaking positions and errors

An exposure device for a platemaking apparatus has: a plate material feed unit consisting of a suction mechanism for feeding and stopping a plate material on an exposure unit, conveyor belts, drive motors and the like; two shielding curtains respectively rolled at two ends of the exposure unit and selectively extended on the exposure unit; shielding curtain drive units for independently driving the two shielding curtains; a setting unit for setting exposure conditions of a document image to be formed on the plate material; and a control unit for controlling the motors of the plate material feed unit and the shielding curtain drive units in a given relationship in response to the conditions set in the setting means, wherein an identical document image is formed on different positions of a single plate material a plurality of times.

Exposure device for platemaking apparatus

A fixing device is provided for a wet type electrophotographic copying machine in which an electrostatic latent image formed on a photosensitive sheet at its face is developed by a liquid developer, and then the liquid developer attached to the photosensitive sheet is squeezed out by a squeezing device before the developed image is thermally fixed on the sheet. The fixing device includes a heater for heating the photosensitive sheet while the latter is being held at its back against the heater as the sheet moves thereon, the heater having a source of heat such as an infrared lamp or tungsten halogen lamp or nicrome wire rubber heater, and a roller made of air-permeable moisture-absorptive spongy material and located in confronting relation to the heater, the roller being pressable against the face of the photosensitive sheet. With such an arrangement, the developed image on the photosensitive sheet can be fixed reliably and thoroughly without fixing marks.

Fixing device for wet-type electrophotographic copying machines

In a copying machine of the type comprising an image projecting lens movable in a direction of an optical axis thereof for varying a magnifying power, a reflecting mirror interlocked with the lens for effecting focusing, and two groups of light sources for illuminating a manuscript, there is provided an exposure control system comprising variable resistors driven by the projecting lens, oscillators for generating pulse signals of frequencies varying in accordance with resistance variations of the variable resistors and with a variation in a source voltage, counters counting the number of the pulse signals in accordance with an exposure index, and switch means for lighting the light sources during intervals determined by an exposure index.

Exposure control systems for use in copying machine

Disclosed is an improved electrophotographic copying machine in which a black frame eliminating mechanism and a random cutting assembly adapted to cut a roll of photosensitive paper to a required length are incorporated. The black frame eliminating mechanism comprises an original supporting window, the length of which is longer than that of an original, an original depressing plate having a white surface facing and covering over the supporting window, means for depositing a charge over the length of a portion of a photosensitive paper, which length corresponds to that of the original, and means for exposing the paper placed at a predetermined position to the light from the entire area of the supporting window. The cutting assembly comprises first, second and third feed rollers arranged in this order along a paper feed passage, first means for driving the first and second feed rollers so as to feed the paper at a first synchronous feeding speed and second means for driving the third feed rollers so as to feed the paper at second feeding speed which is lower than the first speed, a one-way clutch adapted to allow the second rollers to feed the paper only in a downstream direction and cutting means adapted to cut the paper portion between the first and second rollers, wherein cutting of the paper is effected at the location between the first and second rollers when the drive of the first and second rollers is stopped, feeding of the paper is stopped at a position at the first rollers or upstream thereof, and slack of the paper portion between the second and third rollers, caused by difference between the first and second feeding speeds, is being changed to a tensioned condition.

Electrophotographic copying machines

Growing community of inventors

Tachikawa, Japan

Yousuke Igarashi