SU1051487A1 - Automatic system for control of camera exposure - Google Patents

Abstract

AUTOMATIC EXPOSURE CONTROL SYSTEM FOR PICTURES contains two logarithmic elements, two transistors, the emitters of which are connected to the common power supply busbar, which connects the first pins of the logarithm elements, resistors of input of the diaphragm, film sensitivity, shutter speeds and settings, as well as, one, one, one, one, one, one, one, one, one for one. output connected to the input of the storage device, the key of which is kinematically connected to the camera's mirror, and the inverting input is connected A collector of the first transistor connected to the second output of the first logarithm, a galvanometer, an electronic gate and a photodetector, one output of which is connected to the second output of the second logarithm and the base of the second transistor, so as to improve accuracy and thermal stability , it introduced two additional differential amplifiers, additional logarithms. a switching element, an additional transistor, three matched pairs of transistors with an opposite main transistor structure, six additional resistors, a source of reference voltage and a two-way switch for two directions, through the first key of which is in position. the photodetector is connected to the power supply bus, and the emitter of the additional transistor is connected via a second switch and through parallel-connected diaphragm resistors and sensitivity of the film to the common power supply source, with which the emitter of the additional transistor is connected through the setting resistor zero, in the position corresponding to the manual control of the shutter speeds of the electronic camera, the second output of the second logarithm element through the first switch and through the first additional resistor with the bus and power supply source, and the emitter of the additional transistor is connected via the second switch and through the input resistor to the common INNA power source, the base of the additional transistor is connected to the power supply bus and with the second output of the additional logarithm element, the first output of which is connected to the common bus of the power source, and the collector is connected via the third additional resistor to the bus 4 regular enrollment meals and non-inverting input of the first additional speakers | a differential amplifier whose inverting input is connected to the output of a voltage source, with a non-inverting input of the main differential amplifier and the inverting input of a main additional differential amplifier, and the output of the first additional differential amplifier is connected to the bases of the first matched pair of transistors, the collector of one of which is connected to the additional emitter transistor, and the collector of the other with the emitter of the second main trans

Description

an eistor whose collector is connected to one output of a fourth additional resistor; another output of which is connected to the power supply bus; and to a non-inverting input of the second additional differential amplifier, an output connected to the bases of the second matched pair of transistors, the collector of one of which is connected to the emitter of the second main transistor, and the collector of the other through a galvanometer, in parallel to which a fifth additional resistor is connected, is connected to the emitter of the first main transistor Ora, the collector of the connection is: the sixth do1tolnitel1, the RSZ:: 1p with the power supply bus, E.YHOD of the storage device, the substrate is connected to the bases of the third transistor, the collector of one of which is connected to the KTop: .v; ii; Ogarayf world and iyo elemeta, and the collector of the other is connected to the input of the electronic device, and the emitters of all are matched:; x pairs of transistors connected to L -; Noahnaya power supply, - and all the logarith- is: irrrrrrrrrrr the elements are made on the thiax-xra-orax, coordinated with the subrn:, cheny.and they are co The corresponding trans-ST mg mx:

The invention relates to instrumentation, namely to film photographic equipment, and can be used in high-end automatic cameras.

A device for automatically controlling the exposure of a camera is known, which contains logarithmic elements, transistors, resistors, inputs, a galvanometer, an electronic shutter, and a GL photodetector.

The drawback of the device is that the resistors for input of exposure parameters must have non-linear characteristics. . , Closest to the invention is an automatic exposure control system for a camera comprising two logarithmic elements, two transistors, the emitters of which are connected to a common power supply bus through appropriate resistors, which are connected to the first terminals of the logarithmic elements of the film, pegs and installation kul, differential amplifier, output connected to the input of the storage device, the key of which is kinematically connected to the mirror fot an .parata and an inverting input connected to the collector of the first tranzis mountain base connected to the second iyvodom logarifmirutoschego first element galvanometer electrons) Shutter fotolriemnik and having one end connected to the second terminal ptor logarithmic element u. with the base of the second transistor 2j.

The drawbacks of the device include the complexity of the circuit, limited accuracy, thermal stability, and low processability,

To achieve the decree; -.- targets in the system; the 4th automatic control of the exposure for the camera introduced two additional differential amplifiers, the full-field logarithm: 1T1Y e: emek1. up to one trajectory, three three transistor pairs with a tiny basic transistor structure. LijecTb. Additional: X ..) Ezisto; ooob, kstochmik opsrnogo 1: Apr; keni and two-position switch. Gel on two lines1Jerks J. through the first; {1 key which is in position and corresponds to 1:. the photodetector is connected to the power source, and the emitter is an additional transistor; connected via a second switch and through parallel in 1 and 1 resistors of the BVODD1FD and sensitivity of the film to the bus of the power supply source with which the emitter of the additional transistor is connected via the zero setting resistor directly in the position corresponding to the manual control of the electronic shutter speeds of the camera the second output of the second LOG1 11 element is connected through the first key and through the first additional resistor to the power supply bus, and the emitter of the additional transistor is connected through the second switch and via the resistor input resistor to the common power supply bus, the base of the additional transistor is connected through the second additional resistor to the power supply bus and to the second output of the additional lasarfmming element, the first output of which is connected to the bus power supply through the third and an additional resistor is connected to the tin power source and to the non-inverting input of the first additional differential amplifier, the inverting input of which is connected to the output of the source reference voltage, with a non-inverting input of the main differential amplifier and with a non-inverting input of the second additional differential amplifier, and the output of the first additional differential amplifier connected to the bases of the first matched pair of transistors, the collector of one of which is connected to the emitter of the additional transistor, and the collector of the other with the emitter of the second the main transistor, the collector of which is connected to one output of the fourth additional resistor, the other output cat connected to the power supply source, and with the non-inverting input of the second additional differential amplifier, the output connected to the bases of the second matched pair of transistors, the collector of one of which is connected to the emitter of the second main transistor, and the collector of the other through a galvanometer connected in parallel with the fifth additional resistor connected with the emitter of the first main transistor, the collector connected through the open additional resistor to the power supply bus, I remember the output The device is connected to the bases of the third matched pair of transistors, the collector of one of which is connected to the second output of the first logarithm and the collector of the other is connected to the input of the electronic gate, the emitters of all matched pairs of transistors are connected to the power supply bus, and all the logarithm elements are transistors matched with the associated transistors.

The drawing shows a schematic diagram of the device.

The device contains two logarithmic elements 1 and 2, the first 3 and second 4 transistors, the emitters of which through the corresponding resistors 5 and 6 are connected to the common key of the power supply 7, the diaphragm input resistor 8, the exposure input film resistor 9 / resistor 10 installation zero differential amplifier 12, the output of which is connected to the input of the storage device 13, the key 14 of which is kinematically connected to the mirror 15, and the inverted. The tapering input is connected to the collector of the first transistor 3, the base of which is connected to the first logarizing element 1, galvanometer 16, electronic gate 17, and the photodetector 18, one output of which is connected to the second output of the second logarithm element 2 and the base of the second transistor 4, two additional differential amplifier 19 and 20, additional logarithmic element 21, additional transistor 22, three matched pairs of transistors 23-25 with an opposite structure to the main transistors 3 and 4, six additional resistors 26, 31, the reference voltage source 32 and the two-position switch 33 n two directions, through the first key 34 of which in the position corresponding to the automatic mode of operation, the photodetector 18 is connected to the bus of the power supply 7, and through the second key 35 the emitter of the additional transistor 22 parallel-connected resistors 8 and 9 input aperture and sensitivity of the film is connected to a common bus power source 7, with which the emitter of the additional transistor 22 is connected through the zero setting resistor 11, in the position corresponding to Enikeev manual control of the electronic shutter speeds, the first switch 34 connects the second terminal of the second logarithmic element via a fifth further resistor 26 to a power supply 7 of the second bus switch 35 connects the emitter. Additional transistor 22 through the resistor input resistor 10 to the common power supply 7 bus, the base of the additional transistor 2 is connected to the second output of the additional logarithmic element 21 and through the second additional resistor 27 to the power supply 7 bus, and the collector is connected to the source bus through the third additional resistor 7 and is directly connected to the non-inverting input of the first additional differential amplifier 19, the inverting input of which is connected to the output of the source 32 of the reference voltage, with non-inverting input of the main differential amplifier 12 and inverting input of the second additional differential amplifier 20, and the output of the first additional differential amplifier 19 is connected to the bases of the first matched pair of transistors 23, the collector of one of which is connected to the emitter of the additional I-transistor 22, and the collector Friend: Go - with the emitter of the second main

transistor 4, the collector of which are coefficients with one output of the fourth additional resistor 29, the other output of which is connected to the power supply source bus 7 and the non-inverting input of the second additional differential amplifier 20, the output of which is connected to the bases of the second matched pair of transistors 24, the collector of one of which connected to the emitter of the second main transistor 4, and the collector of the other through a galvanometer 16, in parallel with which is connected the fifth additional resistor 30, is connected to the emitter of the first core ovnogo transistor 3, whose collector is via the sixth additional resistor 31 is connected to a power source 7 bus. the output of the storage device 13 is connected to the bases of the third matched pair of transistors 25, the collector of one of which is connected to the second output of the logarithmic element 1, and the collector of the other is connected to the output of the electronic gate 17, and the emitters of all matched pairs of transistors 23-25 are connected to the power supply 7 bus and all logarithmic elements are filled with transistors matched with the corresponding transistors connected to them.

The device works as follows.

The difference in voltage drops across the emitter transitions of matched transistors is determined by their collector currents.

bV-q) -En-llii | lKa.

where Cpj is the temperature coefficient.

This device is built on this property of matched pairs of transistors.

Since all logarithmic elements are made on transistors matched with the corresponding transistors connected to them, the emitters of transistors 3,4 and 22 will have a voltage determined by the logarithm of the ratio of the logarithmic element to the collector current of the resistor connected to it, which in turn is maintained constant by an appropriate differential amplifier, since their outputs through matched pairs of transistors 23-25 control the potentials of the emitters of the transistors corresponding to enno 22.4 and 3.

Thus, the collector currents of transistors 4.3 and 22, respectively, are equal ..

 yy e2 2

.

23

18

s "

where Vi2 is the output voltage of the source 32 of the reference voltage (correspond to the position number of the circuit element).

The currents through the logarithm elements correspond to the collector currents of the transistors, on the CS) -: o) OFJH are built, i.e. collector: the currents of the transistors 2 and 21 are produced by the voltage of the source 7. The power tt is the resistance of the resistors and their circuit. In the automatic exposure control mode, a photoresistor 18 is connected to the l::; 1 arithmic element on the tramistre 2, the current through which is | g - V ;. fc, ::. ie К some coefficient, К -: .. 1 luminance, J 0,5 + 0,9,

Sweet transks-233s perform the function of current multipliers, since the collector currents of the transistors included in them are equal.

So you can write

P "

M1 4124)

where .24 caller: s. matching matched resistors 23 and 24,

t „12

 -tn - 43

 -22

where Rg is the resistance of parallel-connected resistors 8, 9 and 11 of the input of the diaphragm, the sensitivity of the photo: materials and installation. Consequently,

M), Chz

gy

24-R,

-i,

Moreover, the current is the input current of the electronic shutter 17,

Thus, we can write the equation

RC KE fig, -g l 25

PM, - 4 days g, -; -.,

as a result

(-E / l4 r / r6

.1 / l22 R B

By changing the value of the resistor, the exponent indicator under illumination can be increased to 1.0 and a linear connection can be provided, current 175 with illumination on the sensitive area of the photoresistor 18.

The current through the galvanometer 1C in this device is og 1; it is consumed by the expression

t -lo.enil

b-r, r ,, i,

9 Ib

where, is the resistance of the copper coil of the galvanometer, which, like cpc, has a temperature coefficient of + 0.3C, i.e. they compensate each other and the readings of the galvanometer do not depend on the temperature.

In the mode of manual control of the camera shutter speed, the switch 34 to the input of the logarithmic element 2 connects a resistor. 26, and to the emitter of the transistor 22 there is an exposure input resistor 10, by varying the resistance of which the exposure is adjusted.

When you press the shutter-release button of the camera to the device, the galvanometer is powered, it will show the expected shutter speed regardless of the mode of operation. In this case, the mirror 15 is in the initial position and the contacts

key 14 in the storage device 13 are closed.

When the gate is triggered, the pendant 15 rises and opens the contacts 14, resulting in an output current

0 Ijg retains its value until the return of the mirror 15 to the initial state.

The proposed device is much simpler. In its implementation, it has a higher accuracy over a wider range and allows to reduce the error in the temperature range from -20 to + 50s to 0.2 steps without any special thermal compensating circuits.

Claims (1)

AUTOMATIC EXPOSURE CONTROL SYSTEM FOR A PHOTO APPARATUS, containing two logarithmic elements, two transistors, the emitters of which are connected through the corresponding resistors to a common bus of the power supply, to which the first outputs of the logarithmic elements are connected, resistors for diaphragm input, film sensitivity, shutter speed, zero and differential output connected to the input of the storage device, the key of which is kinematically connected to the mirror of the camera, and the inverting input is connected to the the lecturer of the first transistor, the base connected to the second output of the first logarithmic element, a galvanometer, an electronic shutter and a photodetector, one output of which is connected to the second output of the second logarithmic element and the base of the second transistor, characterized in that, in order to increase accuracy and thermal stability, two additional differential amplifiers, an additional logarithmic element, an additional transistor, three matched pairs of transistors with the opposite main transistor, are introduced m structure, six additional resistors, a reference voltage source and a two-way switch, through the first key of which in the position corresponding to the automatic mode of operation, the photodetector is connected to the power supply bus, and the additional transistor emitter is connected through the second key and through parallel input resistors aperture and film sensitivity with a common power supply bus, to which the emitter of an additional transistor is connected through a zero-setting resistor directly, in the position corresponding to manual control of the shutter speeds of the electronic shutter of the camera, the second output of the second logarithmic element is connected through the first key and through the first additional resistor to the power supply bus, and the emitter of the additional transistor is connected through the second key and through the exposure input resistor with the common clay of the power source , the base of the additional transistor is connected through a second additional resistor to the bus of the power source and to the second output of the additional logarithm about the element, the first output of which is connected to the common bus of the power source, and the collector through the third additional resistor is connected to the bus of the power source and with a non-inverting input of the first additional differential amplifier, the inverting input of which is connected to the output of the reference voltage source, with a non-inverting input of the main differential amplifier and the inverting input of the main additional differential amplifier, and the output of the first additional differential amplifier is connected to Zami first matched pair transistors, a collector of which is connected to the emitter of the additional transistor and the collector to the emitter of the other second main tranSU,. "1051487 10 51-187 an eistor, the collector of which is connected to one terminal of the fourth additional resistor, the other terminal of which is connected to the bus of the power source, and to the non-inverting input of the second additional differential amplifier, the output connected to the bases of the second matched pair of transistors, the collector of one of which is connected to the emitter of the second main transistor, and the collector of the other through a galvanometer parallel to which the fifth additional resistor is connected, is connected to the emitter of the first main transistor pa chereva sixth collector coupled to the bus heezistor additional power source, the output memory is coupled to the bases of the third matched pair of transistors, a collector of which is connected with s: t-; output of the first logarithmic element, steam - The flowing OPAX, to the gate IM, and the collector of the other is connected by an input; the electronic emitters of all matched transistors are connected to a power supply ·· - and all the logarithmic elements are made for that agreed with the connection-stages: · corresponding to