DE2008317C - Arrangement for automatic exposure time control in single-lens reflex cameras - Google Patents

Description

The invention relates to an arrangement for automatic exposure time control in one-eyed SLR cameras. Such arrangements consist of a circuit with the help of which a Object brightness: identifying information is linked with further information that the film sensitivity and, if necessary, mark the set aperture.

There are two known principles according to which the decisive object brightness can be determined: They differ in that the light-sensitive Element for determining the object brightness in one case is arranged outside the beam path of the camera lens in the front of the camera housing is, while in the other case it is in the image-side beam path of the camera lens.

Both types of light measurement have their specific advantages and disadvantages. Orders starting with a light-sensitive element arranged outside the beam path of the camera lens are characterized by particularly simple ones Construction from. On the other hand, they have the disadvantage that the measurement on which the measurement is based As a rule, the measurement angle is not identical to the image angle of the camera lens especially with high-contrast objects inevitable measurement errors. Such measurement errors, which are based on a lack of agreement between Measurement and image angles are based on

^ Those with a beam path on the south side of the ^ EKainera lens. Arranged photosensitive are equipped, while avoiding this

However, arrangements have the disadvantage

indicates / that the correction signal Kr that of which by the movement of the Kam caused Äb d ^ u

Albeit with single-lens reflex cameras fixed, permeable sucber mirror! known are, so is the overwhelming majority of all single-lens reflex cameras with an «Is the beam path on the floor side φ * Camera lens swing-out viewfinder mirror. . allowed. Since the movement of the mirror also changes the path to the light-sensitive element is, since this is usually arranged in the viewfinder part of the camera, is with cameras with a movable viewfinder mirror a storage device, ung to be provided in which this identifies the object «Kimccenden signal during the interruption of the to d! n, light-sensitive switching element leading Sn ihleneanes must be saved.

) e invention is based on the object of providing an arrangement for automatic exposure time control for single-lens reflex cameras to create dk- 'the specific advantages of both described Process united in itself. The measurement errors caused by the lack of over-inhibition should therefore be eliminated should occur between the angle of view and the measurement angle of the light-sensitive element the electrical circuit has a comparatively

during the period in a p

(^ B- ^ em Kon & nsator) speicheAar is.

This practice of the invention is brought forward ία part with sieve that controlled ^ J ^^ US

Linearity of the storage element

wise related ^^

hemEiugangswideistand) mine

from only vergltfcbswasβ £ <»*" 1 because the 5 signal to be saved is not

brightness ^ t characteristic in omat.or

whose Vanat.onsbere.ch ^slch . ^^ powers extends, but the us inner and outer M ^chtn ^ ^un 8 ao rekmrsignal, which only has a slight Van

owns. _, Frfin-

Other purposeful training of the inventor Application can be found in the subclaims above

men. .cfr.hruniwLheisniele der

In the Zachnung * ^ ™ ⁿ * £ ° ^l ^ ^e £ J_ invention are represented which to their we ..,, cn Ver

^ _from ^ν

»5 In Fig. 1 bt e
Reception within the

ongoing 'OgtoJ ^

_for the inner door ^ n

Objküv ver

^ SS dadu _rch ge, _ö st that besides a first adjustable in the image-side beam path of the camera lens arranged joined photosensitive member. another outside the beam path of the object is in £ eLmJest

appropriate

^ rd, that on the ™ _iS ch _OT the two Uchtempltod. ^ • "^ aÄSÄTÄSeto '«'"Bchen Ele.nen.en autoelenden Merenzspa ^ ong off and ^α χ ^ £ Α» ώ of the iest adjustable

il. ' ^S _e in particular ", Voneil de, inventu ^ according to .5 Resistance ** is ei": ^

"A corrective signal is usually" essential because " . with the

Amplification of the correction signal required

tivs arranged light

Element working

ine bias of the

i given smd h

Eressenden A, sste ^ rbereich given smd 0 "vSdun ^ point of the collector of the transistor

A further development of the invention is based on the principle that The Ver? ™ "" g ™ _{idcretands 13 is with} the base

sä =; Äf st · ^! rÄ ^ - ^^ -

tromagnet 16 for closing the shutter is directed towards the object to be photographed. then switches. A power source switch 17 is arranged in such a way that the object light that passes through the lens falls that it has gone through all power supply crises of the battery 3 and is the same as that on the film is common. falls on the photoconductor 1 for the inner light

In the F i g. 2 and 6 denote the same reference S reception, while an external light through the light signs as in Fig. 1 each parts with the same receiving window in the front part of the camera goes and Function. onto the photoconductor 4 for external light reception

In the example of FIG. 2, a diaphragm 18 is in front of the falls. The light receiving surface of the photoconductor 4 for the external In the described state is the

Arranged to receive light and can either be used with the camera in the preparatory state of the photographing process depending on the sensitivity of the film used. In this state, the switch 5 on the odci is set to the set aperture value, the break contact α is closed and the two-pole reversing. A variable resistor 2 ', which in switch 8 is closed so that the terminals of the series with the photoconductor 1 for the inner light capacitor 7 is connected to the connection point, can be connected according to the setting of the 15th X ₁ and Y _x which are each set between Blcndc 18. The emitter resistor see the photoconductors 1 and 4 and the fixed adjustable transistor 10 can also be a variable resistors 2 and 6 respectively. Therefore resistor 12 will be as in the example of FIG. 1, and to the terminals of capacitor 7 the voltage between the points X _x and Y _{x can be} determined according to the sensitivity value ao caused by the change of the resistance value and the aperture value can be set, which, depending on the intensity of the light falling on the photoconductor 1, is not influenced in the above-mentioned setting of the light falling on the photoconductor 1 and 4. As a result of the aperture 18 is received. If such an adjustment is not the optical transmission of the objective the chip is intended to use, a fixed resistance at point X _{x can be applied} slightly lower than that at the point. »5 PuuKt Y _x .

In the example of Fig. 3, the current control transistor is in the first stage when the control is depressed

11 of the example in FIG. 1, between the photo isolator button, the two-pole changeover switch 4 for external light reception and the time-wasted switch 8 from the contacts X _x and Y _x to the contact. mcndcn capacitor 9 is used. clocks X _t and Y _{t turned over} . At the next level

In the example of FIG. 4, the current regulating transistor 30 is when the shutter button is pressed down

11 of the example of Fig. 1 is operated only with the battery 3 shutter release, and synchronously therewith is connected, and an electrical measuring device 19 is switched in the switch S to the side of the contact b . Series switched on in this current control circuit, so that a photocurrent controlled by the photoconductor 4 for the outer of the movable part of the measuring device 19, the opening light reception, flows into the capacitor 9, which is timed in front of the light-receiving surface of the photoconductor 4 35, so that the voltage is applied to the outer Light receiving arranged aperture whose clamps increases over time. As you know, 18 hires. becomes the speed of this voltage rise

In the F i g. 5 and 6 are further Ausfühningsfor- on the terminals by the strength of the photocurrent men of the invention. The object brightness scanned in drive is determined in series with and consequently by the resistance value of the photoconductor 1 for the internal light reception.
connection with the dimming process of the lens as a result of switching the two-pole switching

blendc 20 employed, which is the base input of a high input incidence on the photoconductor 1 ters 8 Lichlmcnpe controls. The transistor 11, which has the light impedance, through the on The receiving surface of the photoconductor 4 for the external voltage <5 across the terminals of the capacitor 7

k The diaphragm U arranged on the left is in the pre-tensioned position and controls the output

Tricbsvcr-connection with the little countercurrent. Hence we "" the Eg £ "of Transtand 6 '. the setting of the variable resistor 12 based on this drive connection in series with the photoconductor 4 and sistors IO is determined by the set resistance value dk; or is switched instead. The trigger point of the rsitrs 10 the OhjcktivMcnde 20 in drive vt b with the related to the nsend voltage on the Kkm diaphragm 18. so that the setting enteched the men of the emeoden Kondenstor 9 is carried out blind value (F i g. S). The opening through this Emtttefspanmmg E »determined,
The front of the Uetttempfangsflaebe of the Photointen4 SS The Trisr 10 becomes conductive when the anstet for the external Lkhtempfang ang ao the terminals of the mtbeten-18 is reached according to the sensitivity of the condenser the trigger point, which in

The end of the film is set and the emitter resistance of this weave is caused by the emitter voltage and the

12 of the transistor 10 is driven by raw eieund through the etig of the capacitor 7 the opening setting of the lens end 20 set a difference in activity on the photo

SIdIt (Fig. 6). later 4 iSr the Safieren Lkhtempfang falling The mode of operation of the above-mentioned inventive light and that of the photoconductor 1 for the inner

according to the arrangement is the following:

In the basic example of FIG. 1, where the learned light corresponding to the light is determined, Variable resistor 12 corresponds to the Erap 65 Then the transistor 14 kosest at its base

findKchkeil of the film used or the ciftfc- which at the Veromduagsptnkt of the collector of the trans-

The same blind value is set, the current source transistor 10 and the collector resistor 13 prevail.

switch 17 is closed and the camera is placed on sight, off a conductive

7 ⁸

State in a non-conductive state, so that the sized object brightness information. Therefore, in the case of electromagnet 16, which has prevented the closing of the shutter - this example the rise time of the voltage at ses as a result of the excitation by current supply at the terminals of the time-determining capacitor conductive transistor 14, now loses its corresponding to the already compensated Objekthelig-Maenetkraft and the shutter closed 5 information determined. The predetermined value _w j _r j of this voltage applied to the terminals is released. Therefore, in this basic embodiment, the triggering process on transistor 10 is initiated. The Tranform of the invention the bias of the switching transistor 10 and the following transistor 14 control the sistor by a compensation signal for the from the electromagnet 16 so that it mn a Zjtajh photoconductor for the external light reception i. The information signal for the object brightness is automatically actuated in accordance with the light falling on the film and the night-time shutter table is thereby set where this compensation signal control is carried out. c _{fmmP (} , _ol , i _trP i _e from photoconductor 1 for internal light reception. In the example of F g 4 is in the S rom control loop. w ° d and with this compensation, a of transistor 11 with high input impedance, the Photographing process with the correct exposure 15 from which the compensation signal of the above capacitor 7, which is briefly stored by eTncauTomatic change of the trigger voltage, is controlled in series with an electrical measuring device 19

Terminals of the time-determining capacitor, which drives and sets the diaphragm 18, Cowards aes zeiiDesumimimc _the p _{hotoIeiter4 for externa} ß _ere n

the F1 g. 2 * ^r * ™ »™ P ^ie ° _secured object brightness information is carried out. There-

arranged aperture 18 is «J ^^ ^r JgSg. accomplished. That on the photoconductor 1 for the

possibility of the ^used f ⁿ .. ^ _a ^o _ß ^d ; . ^ denVhoto- 30 internal light reception light falling through dit-

tcn aperture value e.nges eWL so that the J * « ^{n 1} ^. _{affects sen} dimming process. Therefore this is dated

lc.ier 4 falling object light quantities «precnena _{photoconductor} , received object light from the diaphragm

scn, Y ^ert _t ^CI "g ^cscnra " ^kt _H " ^r _e ^d _m ^ _rt ^r Z Information value determined. The opening of the before the photo-

Limitation according to d, csem who * J ^ " _{1ejter 4 arranged for the external} light reception

ntp of the object brightness "™ ™ ^ses ^ _{n In An} . ₃₅ Aperture 18 is in drive connection with the ob-

for the grandiose process ^^ tmmmen _en de _{2Q SQ em} " _{that dje a (] for the photo} _

UK-hsvcrhmdung mit_ diwe; ^ A pJotoSter 1 «gate 4 falling amount of light corresponding to this B-. At the end of 18, the -m series is restricted with the WjJ «aperture value. Therefore they have

for the inner light receiving! lying ^ JJJ _{"d Photo, pus-1 and} 4 correspondingly adjusted Blen Uulcrstand2 set ', so that there ^ ° ™ ^ _ions _ _{4" de} nbedingungen. According to the settings of the

xom capacitor 7 ^^ eUcmT and 4 fade-down 20 and 18 are the variable resistances

sipnal only that of the P " ⁰ « ^ "! ^{1 U} ^ ^ m stands 2 'and 6'. those in series with the photoconductors, 1

keyed object light difference cntspncht * s at sia ^ ^ ^^ _{eingeste "t Bd this together.}

Rospieldcr Fig. ··. _η .;, _η ; »ι the process hanging on the Fie 2, the change in resistance takes place . _B J 1 ,,. _{45 in a} geometric row with the common

through the compensation signal the ^ ""f;"_{Faku> r 2 and the} set aperture values of the

time control through the Emaieiiu "i« f-ste wi-diaphragms 20 and 18 lead to step-by-step changes

* voltage carried out precisely. _if «· _{2 the} photoconductors 1 and 4 and accordingly

Mind 12 'caused by the * Τ »" * ^ Λ5ΐη5ηα- w «« «« ¹ step-by-step changes in the values which are caused by the corresponding emwederaer ^ np g ,,,, ^,. ^ Resistances 2' and 6 '. Lchkcit the "applied film or the eing" * e * «^ _Ό ^ _{correspond to the voltage at point X _v, the aperture value set ^ jr ^ S ^ tmms by the resistance values of the photo lever and the setting of the aperture 18 ^beriKKSIC "" ^s V ₇ . _it . of the variable resistance 2 'is determined, dPnn becomes aie tm in the exposure control ^ ^ _Tension ^ _{n Pm | kt Kj} ^ _dereh ^ _νΛ,. "Vstimmung by these two Werteoeoing · stand values of the photoconductor 4 and the modified example, the F i g .: ³ J ^ i ^^ _n ^ idcfl it- loan resistance is determined 6 ', only by i 4 AESS fd ^ ^{ch a} t P ™ ^ J ^ V ^W 1 d 4 b Obkthlli

p J ^ i ^^ _n idcfl ^ it borrowed

conductor 4 for the outer ^ ^ch t ^a P ™ ^ J ^ V ^W ii · the photoconductors 1 and 4 scanned object brightness determining capacitor 9 em * ™ Τ * 7 ", * _kei , o ^ it is that of the capacitor 7 over-

_kei , o ^ e

high Eingangsimpedat «« "^ f ^ hefvorüber- previously stored signal, the signal of the failure controlled the capacitor 7 ^W ^ T ^. _the on« · between the inner and the Uchtempfang äuße-

going as a voltage to * ^ *** 5l- and from the re ight reception as in the example of Fig. 1. Da-Ph «icHeiterlrWdenmiierCTUchtemi ^« «navom ^ ^^ ^ ^ ^^^ ^^^ ^ ^^ ^

PhtMoleiter 4 for the outer _t ^^^ _/ ^ i ₁ ^ _atim . Kchtungszeitsteuerueg durchgefahr «, whereby

with the accompanying B ⁶ ^^ - ^^^! soekhert. the signal of this capacitor 7 ate Kompenltonsdifferenzsignal serves for the ° ^ ^s ^^ l _a ^ 9 flie- «5 sattonsstgnal. Since the resistance value of the

The one in the ^^ ^bes! ^ ^meod ^ _it Zra ^ iwm Tran- PhototeHers4 for external reception, the Sending current is from P " ⁰ ^" * ^ / IyT _dmc h the charging current of the zat-determining capacitor

sistor U controlled and ^eats f ?? Z _t ^ _a a2. compensated, determined by the set aperture value

Photoconductor 1 for the inner Licntenip · »« ^ -i ~

ίο

is, the time determination is directed under the additional rendering object and the difference signal between

Condition of the set aperture value- see the two of the two elements get-

guided. information signals for the object brightness,

In the example of FIG. 6, the difference signal between the

with the stopping down of the lens aperture 20 as with the 5 more precise signal of the inner light reception and the

Example of Fig. 5 the setting of the actuation signal of the external light reception, is used as a compensation

circuit under control of the photoconductor 4 for the sationssignal to correct the timing

external light reception by setting the trig through the information signal for the object brightness,

voltage of the transistor 10 with respect to the time which is due to the external light reception

determining capacitor 9 corresponding to the io responsive element is used, where-

set aperture value carried out. Therefore, information processing for the legal

With this setting the exposure time control is relatively easy. It

according to the set aperture value and also it is therefore possible to use the advantageous functions of

measured the sensitivity of the film used measuring systems with internal light reception and with

be carried out by the opening of the before 15 external light reception effectively combine and

the light receiving surface of the photoconductor 4 for a correct exposure time control

outer light reception arranged aperture 18 according to a relatively simply constructed arrangement

the sensitivity of the film used. Another advantage of the invention

will provide. is that an automatic exposure time

In an arrangement according to the invention, ao control are elted under different information conditions a more responsive to the internal light reception than the object brightness, such as a set diaphragm element and an assessment of the external light reception and sensitivity of the film used, speaking element against which can be carried out to photographic-.

1 sheet of drawings

Claims (1)

008 Patent claims: 1. Arrangement for automatic exposure control in single-lens reflex cameras S with light measurement through the camera lens, characterized in that in addition to a first light-sensitive element (1) arranged in the image-side beam path of the camera lens, a further light-sensitive element (4) arranged outside the beam path of the lens for direct measurement of the object brightness is provided, and that the voltage controlled by the additional light-sensitive element (4) that occurs is »5 the opening of the camera shutter ^; determining control circuit (9 to 16) is supplied with a correction signal, which is derived from the between the two light-sensitive elements (1 and 4) occurring differential voltage is derived. ao 2. Arrangement according to claim 1, characterized in that the said difference voltage derived correction signal for the duration of the by the movement of the Kamcraspiegcls caused the interruption of the first light-sensitive element (1) leading beam path until the expiry of the camera shutter for a period of time in a storage element [e.g. B. a capacitor (7)] can be stored. 3 » 3. Arrangement according to claim 1 or 2, characterized in that said further light-sensitive element arranged outside the beam path of the camera lens (4) one that regulates the intensity of the light incident on its effective surface Aperture device (18, Fig. 2) assigned is. that the opening of this diaphragm device (18) opens onto the working diaphragm of the camera lens and / or the value representing the sensitivity of the film material used is adjustable and that this setting in connection with an operation, likewise the working aperture and / or film speed corresponding change in one influencing the magnitude of the differential voltage mentioned variable resistance (2 ') takes place. 4. Arrangement according to claim 3, characterized in that the variable resistance (2 ″) with the said first arranged in the image-side beam path of the camera lens light-sensitive element (1) is connected in series. 5. Arrangement according to one or more of the preceding claims with a capacitor which determines the opening time of the camera shutter by its Aufladexeit, characterized in that this capacitor (9) in the emitter circuit of a transistor (31, Fig. 3) can be charged, the base electrode of which has said differential voltage can be supplied as a control voltage (by means of 8) and in whose collector circuit the said further 'light-sensitive element (4) can be switched in as a series resistor (by means of S) . 6. Arrangement according to claims 1 and 2, characterized in that the further light-sensitive element (4; a diaphragm device (* 8, FIG. 4; ) is assigned, the Bbw a contact actuated when the camera is triggered (X '" YJ by the said differential voltage can be adjusted (by means of 19) in such a way that the voltage that occurs on the other light-sensitive element (4) changes for the control the control circuit determining the opening time of the camera shutter corrects this opening time immediately. 7. Arrangement according to Ansprocfc 1, % or 5, in which the light measurement is carried out by the camera lens at its working aperture, characterized in that the further outside the beam path of the camera lens arranged light-sensitive element (4) has the intensity of the incident light on its effective surface regulating diaphragm device (18, F i g.5) is assigned, the opening of which is adjustable to a value corresponding to the set working diaphragm (20), and that this diaphragm device (18) with the actuating ring for setting the Kamcraobjeküvblende and two each with the two light-sensitive elements (1 and 4) in series connected variable resistors (2 'and 6') is mechanically coupled in such a way that the changes occurring in them represent the adjustment amounts of the camera lens diaphragm (20).