SU321792A1 - PHOTOCOPIRAL DEVICE FOR RECEIVING COPIES FROM ORIGINALS - Google Patents

Description

The present invention relates to film photographic technology.

Photocopiers are known for making copies of originals having non-uniform optical densities and maximum contrast, comprising a laser, a scanning system, a condenser, a lens, and a photoelectric feedback circuit.

In order to increase the luminosity of the imaging system, and to simplify the design, in the proposed device, a photoelectric feedback circuit is made in the form of a light guide, the input end of which is connected to the side surface of one of the objective lenses, and the output end is connected to the photodetector laser.

The drawing shows a schematic diagram of the described device.

A gas optical quantum generator of continuous radiation — a laser 1 consisting of a gas discharge tube with a hemispherical resonator — emits a parallel light beam to the scanning system 2 consisting of a specular twelve-sided prism and a drive for its rotation. Rotating around two axes, the prism scans the light spot in the plane of the original 3, which is a photonegative placed between two glass plates.

The optical system 4, made in the form of a three-lens condenser, projects the exit pupil of the laser onto the entrance pupil of the optical system 5 and creates in the plane of the original a bright light spot. The projection optical system 5 is a standard lens that projects the image of the original 3 into the plane of the printing table 6.

From the perimeter of one of the lenses 7 of the objective 5, fiber optic fibers are bred through the holes in the frame, which are then assembled into a beam 8, transmitting a light signal from the original 3 to a photoelectric converter 9, representing a standard photoelectric multiplier sensitive to laser light.

The electronic amplifier device 0 is a conventional DC amplifier with two amplification stages with a gain of about 60. A cathode repeater is used to match the input of the amplifier to the load of the transducer 9.

The power supply unit 11 serves to maintain the electrical discharge in the gas discharge tube of the laser. For this purpose, a rectifier assembled according to a voltage doubling scheme and providing a voltage of 3.5 kV at an output current of up to 50 mA is used. Current on

The gas discharge tube is fed through a GI-30 modulator lamp.

In the plane of the printing table 6, a photographic material sensitive to laser radiation is attached with a presser frame. The photocopies of the original 3 with corrected densities and (or) contrast are recorded on this photo material. This correction is as follows.

The laser light beam 1 formed by the condenser 4, successively through the scanning system 2 — element by element — illuminates the original .3. The size of the elementary light pad is equal to the size of the light beam and is usually 2-3 mm in diameter. Passing through the original-5, the light beam hits the first lens 7 of objective 5. Due to light scattering in the glass, part of the light energy through the fiber light guide 8 enters the converter 9. The amount of light energy fed to the phototransducer 9 will be proportional to the optical density of the elementary The pad, the original 3 puffs at the moment.

An electrical signal from the converter 9, which is a function of the optical density of this original area, enters the device 10, which amplifies the signal to a value sufficient to control the current of the discharge tube of the laser). Control of the current value. It occurs by applying an amplified signal to the grid of the GI-30 modulator lamp of the power supply unit 11 of the laser. By controlling the current of the gas discharge tube, the laser radiation 1 is modulated. Thus, as it moves through the original 3, the brightness of the light beam changes depending on the optical density of the original, i.e., the exposure of each photocopy element on the printing table 6 is determined

as the optical density of the original 3, and the brightness of the laser 1 at the moment. When a dense area of the original is scanned, the laser brightness increases, and when it is transparent, it decreases. As a result, a copy with reduced unevenness of optical densities and (or) with reduced contrast is fixed on the photo paper in the plane of the printing table 6.

In order to control the brightness of the light as the beam travels along the original 3, in the described projection photocopier, the laser is internally modulated by the current of the gas discharge tube, and for

The light scattering effect in glass is used to remove some of the light energy from the original, for which light energy from the fiber of the optical fibers 8 is directed from one of the objective lenses 5 to the photoconverter 9

to the feedback circuit.

Subject invention

Photocopier for copying originals with non-uniform optical densities and maximum contrast containing a laser scanning

A system, a condenser, a lens and a photovoltaic feedback circuit, characterized in that, in order to simplify the construction and increase the luminosity of the imaging system, the photoelectric feedback circuit is designed as a light guide, the input end of which is connected to the lateral surface of one of the objective lenses, and the output end is connected with a photodetector, the output of which is connected through an amplifier of a laser power supply unit.