RU2000596C1 - Device for photographic printing - Google Patents

Abstract

Usage: for determining exposure and working time during photo printing Summary of the invention: the device comprises a photodetector, a light-current converter, a constant current source, a setting resistor, an adjustment resistor, two threshold elements, a timer, a charging current source, a storage capacitance time, three electronic a key, an indicator element, a switch, a control unit, three mode buttons, two triggers, two logical elements

Description

The invention relates to photographic equipment and can be used to determine exposure and work time in photo printing.

A device is known for automatically adjusting exposure during photo printing from negatives to black and white and color photo paper (see A. S. USSR M; 714342, class G 03 B 27/78, 1980). This device contains a photocell, a block of measuring capacitors, a measuring amplifier comparing a threshold device made in the form of a thyristor optocoupler, and a control circuit for the tubes of the photo magnifier.

The capacitance of the measuring capacitors is charged, depending on the illumination of the photocell, by the light of a photo enlarger lamp that has passed through negative and photo paper. Its potential is amplified by a measuring amplifier and enters the threshold device. Upon reaching

the output of the signal amplifier equal to the threshold, the threshold device extinguishes the photographic enlarger lamp, stopping the exposure.

A disadvantage of the known device is the inconvenience in its use, due to the fact that this device does not allow a preliminary analysis of the negative and measure the exposure value depending on the illumination of the most critical part of the frame, and then use the obtained value of the multiple photo prints to obtain identical pictures in quality , and also set it manually when creative amateur photographer. In addition, the orientation of the photodetector is difficult. Another disadvantage of the device is a significant error when printing from contrasting negatives, due to that. that the photodetector has a large surface area, which is perceived o o o

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It has integrated illumination from a relatively large portion of the frame.

Also known is a light meter on transistors (see G. Fedotov, Electrical and Electronic Devices for Photography. L .: Energoatomizdat. Leningrad Branch, 1991, pp. 77-80). The device contains a photosensor, a light-current converter. a setting resistor to set the sensitivity of the exposure meter depending on the type of paper used, a variable resistor to set the shutter speed, an indicator element to determine when the shutter speed was set correctly by a variable resistor, an operating mode switch, as well as a time setting capacitance and a charge source. The device operates both in exposure mode and in a time interval count mode.

In exposure mode, the remote sensor is placed in the most critical part of the frame. The moment of correct exposure setting is determined by the appearance of a weak glow of the indicator element at a certain position of the movable contact of the variable resistor. In the time interval countdown mode, by pressing the time button, the driver capacitance is connected to the charge current source for its fast charge. The countdown of the time interval starts from the moment the button is released, while the capacitor is discharged through the measuring circuit of the device (variable resistor).

The disadvantages of this device are the inconvenience in use and the low accuracy of measuring and working out the exposure value.

Inconvenience in use is due to the fact. that the circuitry of the device does not allow to cover a wide range of used photo paper. In addition, the process of working out the exposure requires increased attention of the user, since to charge the time of the set capacitance, it is necessary to press the button and keep it pressed for a certain time, and to start the timer, release it. Since the time the button is pressed and the moment it is released are subjectively controlled, errors may occur in practicing the set exposure.

The low accuracy of measuring and working out the exposure is also due to the fact that, due to the nonlinearity of the discharge, the time of the supply capacitance, as well as the bias of the criteria for the correct exposure setting (weak glow of the indicator lamp), errors in determining and working out the measured exposure value are possible.

The closest to the invention in terms of the combination of essential features and the achieved result is a device for photo printing (a.s. USSR No. 1659922, class G 03 B 7/08, 1991). The device comprises a series-connected photodetector and a light-current converter, a timer consisting of the time of the driving capacitance, a charge current source and a threshold element, an adjustment resistor and a switch.

When measuring illumination, the circuit operates on the principle of a bridge. An adjustment resistor sets the balance of the bridge. The value of the resistor set determines the discharge time of the timer capacitance.

0 The disadvantages of this device, as

and the above analogue, there are inconvenience of use and low accuracy of exposure exposure.

Inconvenience of use due to

5 in that the device does not have a constant exposure time scale. This makes it difficult to use with color photo printing, when it is necessary to adjust the exposure time by several percent. The device also does not allow the use of all types of existing photo paper with different sensitivity and contrast, since the threshold device is configured with a constant response threshold. To a small extent, the data of the photographic material used can only be changed by charging the capacitor, and this is due to the use of another (or additional) source of charge. Another disadvantage of using the device is the inability to terminate the exposure process at the request of the user.

Low exposure accuracy

5 is caused by the nonlinearity of the discharge, the time of the master capacitance, and also the fact that the charge time of the capacitance and the moment the timer starts are subjectively controlled by the user, which leads to errors when

0 exposure testing.

In addition, the presence of electromechanical switches in the measuring and timing circuits reduces the reliability and accuracy of the instrument.

5 An object of the invention is to improve usability and accuracy in measuring and developing exposure.

The goal is achieved in that a control unit equipped with buttons is inserted into a photo printing apparatus comprising a photodetector and an illumination-current converter, a current timer, a timer consisting of a set capacitance, a charge source and a threshold element, as well as an adjustment resistor and a switch. mode settings, a second threshold element, the first input of which is connected to the installation resistor, a constant current source, first, second and third electronic keys and an indicator element, and the pickup resistor is equipped with a delay time scale, the outputs of the illumination converter - current and the constant current source are connected to the control resistor and the first and second inputs of the first and second threshold elements, the output of the charge current source is connected to the time of the driving capacitance and the second input of the first threshold element, the first and second inputs of the control unit are connected respectively to the outputs of the second and first threshold elements, the first, second and third outputs of the control unit are connected respectively through the first, second and third electronic switches with the control input transducer illumination - a current source and a DC source and the output of the charging current, and the fourth and fifth n outputs of the control unit are respectively connected with a switch and an indicator element.

The presence in the device of a control unit equipped with mode buttons allows you to organize the operation of the device in three modes by simply pressing the buttons: the Measurement mode, the Timer mode and the Start timer mode, while in the Measurement mode the device operates as an exposure meter, the timer threshold is set in the Timer mode the first threshold element corresponding to the measured exposure time, in the Start timer mode, the measured exposure time is processed by charging the time of the reference capacitance from the source of charge about current.

The presence in the device of the exposure time scale located on the adjustment resistor and which is common for both the exposure meter and the timer allows in the Measurement mode to find the position of the movable contact of the adjustment resistor that corresponds to the illumination of the negative and the given sensitivity of the photo paper, and in the Timer mode set the response threshold corresponding to the value of the exposure time scale, which is then processed in the Start timer mode. At the same time, the user’s functions are minimized, it is possible to change the shutter speed for creative amateur photographers, when switching from black and white to color photo printing, use it as a regular time switch, which increases the usability of the device.

The presence in the device of a light indicator controlled through the control unit

10 by the signal of the second threshold element, it allows to precisely initiate the moment of the correct exposure setting and thereby increase the accuracy of exposure measurement. The exposure working time is determined by the charging time of the drive capacitance from the direct current source according to a linear law, which increases the accuracy of the exposure working, in contrast to the prototype device, where the working time is determined

0 capacity discharge time according to nonlinear law. This eliminates user functions such as pressing a special button to charge the tank for a certain (approximately controlled) time, which also improves usability.

The device allows you to work with all existing types of photo paper; it does not contain electromechanical switches for measuring and timing circuits, which allows to increase the reliability and durability of the device.

The drawing shows a schematic diagram of the claimed device for

5 photo printing.

The device comprises a control unit 1, a photodetector 2 connected in series, and an illumination-current converter 3 — current, a constant source 4

0 current, setting resistor 5, adjustment resistor 6. equipped with a dwell time scale, first threshold element 7. second threshold element 8, timer 9, consisting of a charge source 10 source 10, the output of which is connected to the setting capacitor 11 and the second input the first threshold element 7. The outputs of the Converter 3 and the source 4 of the DC current connected to the regulation resistor

0 6, the first and second inputs, respectively, of the first threshold element 7 and the second threshold element 8, the first input of which is connected to the movable contact of the installation resistor 5, and the output is connected to

5 to the first input of the control unit 1 The second input of the control unit 1 is connected to the output of the first threshold element 7. The first, second and third outputs of the control unit 1 are connected respectively through the first, second and third electronic

switches 12, 13 and 14 with the control inputs of the converter 3. DC source 4 and the output of the charge source. The fourth and fifth outputs of the control unit 1 are connected respectively to the indicator element 15 and the switch 16.

The control unit 1 is provided with pseudo-touch buttons 17. 18 and 19 of the mode setting respectively Measure, Timer, Start timer. In addition, it contains triggers 20 and 21, logic elements 2NE-OR 22 and 23, logic elements 2I-NOT 24 and 25, S-inputs of triggers 20 and 21 are connected respectively with buttons 17 {Measurement) and 19 (Start timer ), and R-inputs - with button 18 (Timer), D-input and C-input of trigger 20 and D-input of trigger 21 are connected to a common button. The direct output of the trigger 20 is connected to the first input of the 2I-NOT 24 element and the first output of the control unit 1, the inverse output of the trigger 20 is connected to the first input of the 2NE-OR 22 element and the second output of the control unit 1. The inverted output of the trigger 21 is connected to the second inputs of the 2HE-OR elements 22 and 23 and the third output of the control unit 1. The output of the 2N-NOT 24 element is connected to the first input of the 2HE-OR element 23. The output of which is connected to the fourth output of the control unit, the output of the 2HE-OR 22 element is connected to the fifth output of the control unit. The second input of 2I-NOT 24 is connected to the first input of the control unit 1, the first and second inputs of 2I-NOT 25 are connected to the second input of the control unit 1, and the output of 2I-NOT 25 is connected to the C-input of trigger 21.

A device for printing works as follows.

Place the photodetector 2 in the most critical part of the frame. Using the setting resistor 5, the sensitivity data of the photo paper used is input. In this case, the set voltage is supplied in the form of a reference signal (threshold) to the first input of the second threshold element 8.

When the user presses the 17 Measurement button, the device acts as an excimeter. In this case, the control unit 1 of the signal from the direct output of the trigger 20 opens the electronic key 12, the signal from the direct output of the trigger 20 opens the electronic key 12, the signal from the inverse output of the trigger 20 through the 2НЕ-OR 22 element includes the switch 16 (controlling the photographic enlarger lamp, not shown) and the signal from the inverse output of the trigger 21 includes an electronic key 14.

In this case, the illumination converter 3 - the current generates a current proportional to the illumination, which, flowing through the adjustment resistor 6, creates a voltage on it, the value of which is proportional to the output current of the converter 3 and the resistance value of the resistor 6. This voltage is supplied from the adjustment resistor 6 to the second output of the second threshold element 8. By moving the movable contact of the adjusting resistor 6, the user achieves a voltage drop thereon equal to the voltage of the threshold threshold of watts of the threshold element 8 is fed to the second input of the 2I-NOT 24 element, at the first input of which there is a single signal from the trigger 20. The output signal of the 2I-NOT 24 element through the 2NE-OR 23 element goes to the indicator element 15, which lights up, indicating by the correct exposure time. The position of the movable contact of the adjustment resistor 6 indicates this value on the exposure time scale.

After determining the exposure time, the device is switched to Timer mode by pressing button 18. In this case, the trigger 20 on the R-input is reset, the electronic key is closed by the signal from its direct output and the indicator element 15 is extinguished through the elements 2I-NOT 24 and 2I-NOT 23. the signal from the inverse output of the trigger 20 through the 2HE-OR element 22 turns off the switch 16 and opens the electronic switch 13, which connects the DC source 4 to the regulation resistor 6. The voltage generated from the regulation resistor 6 is proportional to Installed mode Measure the exposure time. This voltage is applied to the first input of the threshold element 7 and sets its threshold. The electronic key 14 in the Timer mode remains open, the time setting capacitance 11 is discharged.

To work the set holding time, press the 19 Start timer button. In this case, the signal 14 is closed by the signal from the inverted output of the trigger 21. The indicator element 15 is lit through the 2HE-OR 23 element, and the switch 16 is turned on through the 2HE-OR 22 element (the photo-magnifier control lamp is not shown in the drawing). In time, the drive capacitance 11 is connected to the charge current source 10. An increasing voltage is generated on the capacitor 11, which is fed to the second input of the first threshold element 7. At the moment of equal voltage for the time of the setting capacitor 11 and the regulation resistor 6, the first threshold element 7 provides a signal to the first and second inputs of element 2I-NOT 25 of block 1 control, which stops the processing of the exposure time. In this case, the output signal of the element 25 is supplied to the C-input of the trigger 21, the output of which opens the electronic key 14. The switch 16 and the indicator element 15 are turned off. Time setting capacitor 11 is discharged through the electronic key 14.

At the request of the user, the shutter speed mode can be set. To do this, press the 18 Timer button. In this case, the switch 16, the indicator element 15 are turned off by a signal from the inverted output of the trigger 21, the electronic key 14 is opened, through which the time of the setting capacitor 11 is discharged.

Claims (1)

SUMMARY OF THE INVENTION A photo printing apparatus comprising series-connected photodetectors and a light-current converter, a timer consisting of a time of the driving capacitance, charge current sources and a threshold element, as well as an adjustment resistor and a switch, which are incorporated in it a control unit provided with mode setting buttons, a second nopoionoin element, the first input of which is connected to the installation resistor, a constant current source, first, second and third electronic keys and an indicator element, the adjustment resistor provided with a delay time scale and the converter outputs, the adjustment resistor provided the exposure time scale, the outputs of the illuminance converter - the current and the direct current source are connected to an adjustment resistor and the first and second inputs of the first and second threshold of the output elements, respectively, the output of the charging current source is connected to the time of the driving capacitance and the second input of the first threshold element, the first and second inputs of the control unit are connected respectively to the outputs of the second and first threshold elemengs, the first, second and third outputs of the control unit are connected respectively through the first, second, and third electronic keys with control inputs for the illuminance converter — the current of the constant current source and the output of the charging current source, and the fourth and fifth outputs of the control unit ION connected respectively to a switch and indicator member. AND w from 27 - about iRi T fal Sho 25, , /5  g1 g G