SU901984A1 - Device for photographic printing - Google Patents

Description

(5if) PHOTO PRINTING DEVICE

one

The invention relates to instrumentation, in particular, to a technique of photographic printing, and can be used, for example, in creating devices for automatically reducing (masking) or increasing (demasking) the overall contrast of negatives when receiving photo prints, for example, printing photocopies in aerial photography, in a special and scientific photo. - „

Known electronic copy

a device, which is a contact printing device, built according to a running beam deployment scheme, in which a cathode ray tube is used as an adjustable light source, on the screen of which a rectangular raster is formed using a deflection system connected to a sweep generator . The device also contains an optical system - projecting engine

The light beam is placed in the plane of the original on a transparent substrate, which is in contact with the photosensitive material on the light-diffusing substrate, a photoelectric converter and a feedback amplifier. A moving light spot creates on the screen of a cathode-ray tube a mask image with a density distribution depending on the optical density distribution of the original tl The disadvantage of this device is a small masking coefficient (the ratio of the width of the original optical density range to the width of the equivalent density range created by the original and mask position) . This disadvantage is due to the limited density range of the mask.

The closest to the proposed technical entity is the Photo Printing Device, which contains a light source, namely, an electron beam tube with a deflecting system associated with a sweep generator and an optical system. The optical system consists of two lenses, a semi-transparent mirror located at an angle of 45 ° to the optical axis of each lens, and an original holder on a transparent substrate with a photosensitive material on a light-diffusing substrate. The optical system is located between the light source and the two photoelectric converters. The optical input of one of them is located on the optical axis of one of the lenses after the original holder with photosensitive material. The optical input of the second photovoltaic converter is located on the optical axis of the secondary lens. The outputs of the first and second photoelectric converters are connected respectively to the inputs of the first and second logarithm. The outputs of the logarithm are connected respectively with the first and second inputs of the subtractor. The output of the subtractor is connected to the input of an amplitude control device, the output of which is connected to the input of a non-linear equalizer. The output of the non-linear corrector. Is connected to one of the inputs of the second subtractor, the output of which is connected through an amplifier to the electrode of the electron-beam tube. The output of the second logarithm is also connected to the input of the sweep generator. The output of the sweep generator is connected to the input of the third logarithm. The output of the third logarithm is connected to one of the inputs of the third subtractor. The second input of the third subtractor is connected to the output of the first logarithm. The output of the third subtractor is connected to the input of the second amplitude control device. The output of the second device for adjusting the amplitude is connected to the second input of the second subtractor 2. A disadvantage of the known device is the low masking and unmasking coefficient, which is caused by the fact that when the output of the first logarithm is connected to the input of the third subtractor, the range of the spot brightness control on the cathode tube decreases by reducing

the range of the signal arriving at the input of the first loragemater from the output of the first photoelectric converter. In addition, when the output of the second logarithm is connected to the input of the sweep generator, the range of adjustment by the scan rate decreases, and the mask distorts the density of the original as well. Decreasing the ranges of modulated parameters (spot brightness on the screen of the cathode ray tube and scanning speed) leads to a decrease in the density range of the mask image on the screen of the cathode ray tube. Thus, the distortions of the mask density versus the original densities and the small mask density range determine the low coefficient of masking to unmasking. Another disadvantage is the impossibility of obtaining a unmasking coefficient comparable to the masking coefficient due to self-excitation in a feedback loop, which must be positive for the unmasking mode to be implemented.

The purpose of the invention is to improve the quality of prints.

The goal is achieved by the fact that the device for photo printing, containing a light source in the form of a cathode ray tube with a deflecting system associated with a sweep generator, an optical system consisting of two lenses, a translucent mirror located at an angle of kS ° to the optical axis of each the lens, the original holder with photosensitive material and located between the light source and photoelectric converters, the outputs of which are connected to the inputs of the corresponding logifiers, the output The second subtractor, a voltage source, an inverter, a switch, three attenuators and two antilogifiers, and one of the outputs of the voltage source are connected to the third input of the first subtractor, and the second output of it is connected to one of the inputs of the second subtractor, two pipe inputs of which are connected to the outputs of logifiers, and its output is connected one of the switch inputs, the second input of which through the inverter is connected to the output of the first subtractor, the output of the switch is connected to the input of the amplitude control device, the output connected through a corrector to the input of the first attenuator, the output connected to the inputs of the second and third attenuators, the outputs of which are connected respectively anti-log to the input of the sweep generator and to the electrode of the cathode ray tube.

The drawing shows a kinematic diagram of the device.

The device for photo printing contains a cathode-ray tube T with a deflecting system 2. The output of the sweep generator 3 is connected to the input of the deflecting system 2. Before ; The screen of the cathode ray tube 1 is located at the lens D, Behind the lens, a translucent mirror 5 is located on its optical axis. Its plane forms an angle of 5 with both the optical axis of lens A and the optical axis of the second lens 6. After the translucent mirror 5 on the optical axis of the lens 4 the holder 7 of the original 8 is located on a transparent substrate and a photosensitive material 9 on a light-diffusing substrate. The light flux from the photosensitive material 9 on the light-diffusing substrate is fed to the photoelectric converter 10, the output of which is connected to the input of the logarifmator 11. The light flux from the third lens 6 is fed to the photoelectric converter 12, the output of which is connected to the input of the logarifmator 13. The photoelectric converters in the device photomultiplier tubes. The output of each logarithm 11 and 13 is connected to one of the inputs of the subtractors I and 15. The third inputs of the sub switches I and 15 are connected respectively to the first and second outputs of the source 16 of the reference voltage. The output of the subtractor 14 is connected to the input of the inverter 17. The output of the subtractor 15 is connected to one of the inputs of the switch 18, the second input of which is connected to the output of the inverter 17 The output of the switch 18 through the serially connected device 19 for amplitude control, the nonlinear equalizer 20 and the attenuator 21 are connected to the inputs attenuators 22 and 23. The amplitude adjustment device is a series-connected adjustable attenuator and amplifier. The output of the attenuator 22 through the anti-logifier 24 is connected to the input of the sweep generator 3. Attenuator 23 through the anti-logifier 25 is connected to the electrode of the cathode ray tube i.

The device works as follows.

In the masking mode, the luminous flux (signal) from the scanning spot on the screen of the cathode ray tube 1 through the lens 4, reflected from the translucent mirror 5 through the lens 6 enters the photoelectric converter 12. This signal is proportional to the brightness of the spot. The main part of the light flux (signal) from the spot on the screen passes through the lens 4, the translucent mirror 5, the holder 7 of the original 8 n in a transparent substrate and the photosensitive material 9 on the light-diffusing substrate and hits the photoelectric converter .10. This signal is proportional to the product of the luminance of the spot and the transparency of the elementary part of the original.

The light signals are converted by photoelectric converters 10 and 12 into electrical signals, which are logarithmized by logifiers 11 and 13. By subtracting the signals from logifiers 11 and 13 by subtractor 15, a signal is obtained that is proportional to the optical density of the elementary portion of the original. The signal from the output of the 16-reference voltage source arriving at the inlet of the subtractor 15 displaces (assigns one of the boundaries of the density range of the elementary portion of the original to an established fixed value, for example, zero, which is one of the steps of matching this range with adjustable parameter ranges.

Claims (2)

From the output of the subtractor 15, the signal is fed to the input of the device 19 for amplitude control. Due to a certain transfer coefficient of this device to another fixed value, the Other boundary of the density range is brought, which is the third step in matching the original density ranges and the adjustable parameters. The signal is then converted by a non-linear offset 20. The nature of the transformation with the operator chooses the outcome from the special requirements for the fingerprint. After that, the signal is attenuated to some extent by attenuator 21, which determines the magnitude of the masking coefficient. The signal is then applied simultaneously to two attenuators 22 and 23. After each attenuator 22 and 23, the signal is converted by the corresponding anti-logarifiers 2 and 25 and fed respectively to the input of the sweep generator 3 and the electrode of the electron-beam tube 1; In this case, the greater the density of the original corresponds to the greater brightness of the spot and a lower scanning speed. In the demasking mode, the difference is that the subtraction of the signals from the logifiers 11 and 13 is performed by the subtractor 14, with the decrement and subtraction being swapped. Using the signal from the source 16 of the reference voltage and inverting by the inverter 17 leads to zero, unlike the previous mode, the other end of the density range of the original, after which the signal enters the input of the device for controlling the amplitude 19. Otherwise, the device works the same as in previous mode. In this case, a higher optical density of the original corresponds to a lower brightness of the spot and a higher scanning speed. Using a device for photo printing, for example, when creating photo printing devices designed to automatically reduce or increase the overall contrast of negatives when receiving photo prints such as aerophotography, X-ray, special and scientific photography, improves the quality of prints when the optical density range of the original (negative ) with a range of exposures of the photosensitive material. The masking and unmasking coefficients, the magnitude of which determines the possibility of matching the ranges, can be increased in comparison with the known instruments. An image printing device comprising a light source in the form of a cathode-ray tube with a deflecting system associated with a sweep generator, an optical system consisting of two lenses, a translucent mirror positioned at an angle iS to the optical axis of each lens, an original holder with photosensitive material and located between the light source and photovoltaic cells, the outputs of which are connected to the inputs of the corresponding logifiers, the outputs connected to responsive to the first and second inputs of the subtractor, and an amplitude control device and a nonlinear corrector connected in series, characterized in that, in order to improve the quality of the prints, a second subtractor, a reference voltage source, an inverter, a switch, three attenuators and two antilohearifters, one of the outputs of the voltage source is connected to the third input of the first subtractor, and the second output is connected to one of the inputs of the second subtractor, the other two inputs of which are connected to the outputs of the logarithm, and its output is connected to one of the switch inputs, the second input of which through the inverter is connected to the output of the first subtractor, the output of the switch is connected to the input of the device for amplitude control, the output connected through a corrector to the input of the first attenuator, the output connected to the inputs of the second and third attenuators, the outputs of which are connected respectively through the appropriate anti-logifiers to the input of the sweep generator and to the electrode of the electron-beam tube. Sources of information taken into account in the examination 1. Electronic-copying installation Elcop Herdak.MI1itSr-technic, 1967, К 1. c.2if-27. 2. Switzerland Patent No. 453878, cl. 57 a, 8/05, 1968 (prototype).