DE2463382C2 - Electronic exposure control device - Google Patents

Description

The invention relates to an electronic exposure control device for a camera according to the Preamble of claim 1.

A known camera this / type (DE-OS 21 33 212) is a so-called dual-priority camera in which the Control carried out in each case in the shutter priority device and in the aperture priority device can be. While a user of cameras having such a dual priority mode Can achieve images to his taste, there is a risk for him to take a cheap snapshot to miss, because before the shutter release in such cameras, first a shutter speed or must set an aperture value. Furthermore, a camera having such a device has poor handling characteristics or maneuverability, since either a shutter speed or an aperture value can be set and a beginner can moreover set a shutter speed or an aperture value Set the aperture value that gives an adequate exposure

Such inadequacies can be avoided by, for example, DE-OS 20 31 978 known facility, d. H. by adding a program exposure mode in which a relationship between an aperture value and a shutter speed automatically based on the Brightness of an object can be determined.

However, if such a program exposure control mode is changed to the dual priority mode When the camera is built in, a variety of obstacles will arise which make a practical one Oppose the use of the camera.

As a new mode setting member for setting a program control mode in addition to the two Mode setting members for setting the priority control modes will therefore not only be required The camera, which should have a compact size, is larger but it also becomes the training of the camera more complicated and such a camera requires a high cost, which constitutes significant disadvantages.

Also must when changing from a shutter or aperture priority mode to a program control mode is made, at least two operational measures are carried out. For example, if a shutter priority mode is converted to a program control mode, a program control mode setting member must be provided operated and at the same time an aperture value setting ring from its special position be released. And if this release of the aperture value setting ring is forgotten, it becomes an erroneous one Enter operation and correct exposure control cannot be performed. In contrast furthermore, if there is a change from a state in which a program control into a Shutter or diaphragm priority mode is converted, two operations are also carried out and forgetting these two user actions will naturally result in faulty Lead the way of working.

The object of the invention is to provide an exposure control device while avoiding these disadvantages for a camera in which the addition of a program controller to a camera provides a dual priority function containing conventional camera without adding any new special handling member is realized in which a switching operation between each priority function setting and one Program control setting can be made with a single measure and not a faulty one Operation will take place, as well as all requirements regarding manufacturing costs and thus manufacturing effort on machines and material as well as handling characteristics or maneuverability and Security in error-free use is sufficient.

This object is achieved by the measures characterized in claim 1. The invention has such a structure that a program control mode is set when one for setting a Il aperture priority control mode serving setting member and for setting a shutter priority mode

dus serving setting member are both set and it is therefore not necessary to use a new setting member

Establish a program control mode to be provided. The construction of the camera is therefore simple and one Camera can be manufactured at low cost and can be small in size.

But since the change from a shutter priority control mode or an aperture priority control mode A program control mode can be made in a single step, too will the Handiness and handling characteristics increased Da recording in a program control mode can of course be made, even a beginner in the field of recording technology can easily make a recording and it also increases the fear of missing out on a cheap snapshot opportunity degraded

The invention is to be explained in more detail, for example, with the aid of the drawing. It shows

F i g. 1 is a front view of a single lens reflex camera in which an exposure control device is usable according to the invention;

F i g. 2 is a top view of the camera in FIG. 1;

F i g. 3 is a rear view of the camera in FIG. 1;

F i g. 4A to 4C show a block diagram of an embodiment of a control device according to the invention;

F i g. 5A and 5B show a flow chart for explaining the mode of operation of the control device in FIG. 1; F i g. 6A to 6B are flow charts for explaining the exposure calculation in connection with FIG. 2;

F i g. 7 is a diagram for explaining exposure control in program photography;

F i g. 8 is a block diagram of a single lens reflex camera to which an automatic exposure control device is provided; and

F i g. 9 is a graphic illustration to explain the mode of operation of the program photography of the in F i g. 4 illustrated system.

In Fig. 1 the important parts of a single-lens reflex camera with an exposure meter; ^ ng through illustrated through the lens, a first embodiment of an exposure control system according to FIG of the invention is used

In the camera body 2 are a shutter mechanism, a film advance mechanism, a viewfinder, an exposure control mechanism, etc. Furthermore, a lens 4 is attached to the camera body 2, which has a mechanism to the lens-side information, for example whether the aperture is fully open to transmit the aperture value of the lens, etc., to the camera body 2; further is a Diaphragm adjusting mechanism and a range finder mechanism are provided. By means of a film rewind mechanism 8, the film wound by the film transport mechanism can be rewound. At a setting disk 10, the sensitivity of the film used can be adjusted. By means of a Counter 12, the recordings made are counted Λη an observation window 14 is provided in the viewfinder. A release button 16 is assigned to the shutter mechanism. On the lens 4 there is an aperture setting ring provided, on which the aperture value can be selected and set. Setting marks 20 and 22 respectively indicate the upper and lower limit values for the maximum and minimum aperture value, respectively, if a photographer has decided on the aperture value, which is determined automatically by a calculation will.

A setting disk 24 attached to the camera body 2 is used to select and set the shutter speed Setting markings 26 and 28 respectively indicate the shortest or longest time, ie the so-called maximafe or mininHe exposure time, in peak values when a photographer is interested in the exposure time has decided which one is automatically determined on the basis of a calculation. A selector switch 30 for fully automatic operation can be set to an ON position if the photographing is to take place automatically. This means that if you want to take photos with the so-called priority aperture setting, the required aperture value is selected and set by means of the aperture setting ring 18 and at the same time the exposure time setting dial 24 is moved to the "AUTO" position, thereby automatically determining the exposure time 2u. Finally, the desired maximum or minimum exposure time is also set by means of the setting markings 26 and 28 provided for this purpose. Then, if the exposure time obtained through the calculation is not between the originally set maximum and minimum value, the maximum value (if the result obtained through the calculation is above the maximum value) or the minimum value (if the result obtained is below the minimum value) is used as the newly set exposure time in order to calculate and change the originally set aperture value, so that a suitable exposure time is then finally obtained. If, on the other hand, you want to take photos with the so-called priority exposure time setting, the desired exposure time is selected and set by means of the exposure time setting dial 24 and at the same time the aperture setting ring 18 is brought to the "AUTO" position in order to automatically determine the aperture value; Finally, the desired maximum and minimum aperture values are set by means of the setting markings 20 and 22 provided for this purpose. If the aperture value obtained by the calculation is not between the originally set maximum and minimum value, the maximum value (if the calculated result is above the maximum value) or the minimum value (if the result is less than the minimum value) used as the newly set aperture value to calculate the originally set exposure time and to change μ, so that a corresponding exposure time is then finally obtained.

The program constant can be set and entered by means of a setting device 32. if then both the aperture value setting ring 18 and the exposure time setting ring 24 in the "AUTO" position are set and if only the maximum and minimum value based on the decision of a photographer are set, the optimal aperture value and the optimal exposure time will be according to the previously constant setting made. By pressing a button 34, a so-called automatic exposure, to be carried out; that means when the image which is optically felt, and the picture to be taken differ from each other, the aperture value or exposure time information

Mation, which are determined on the basis of the optical sensing by calculation, retained until the shutter is released or the recording is finished. A self-timer can be set by means of an adjusting lever 36 if photography is to be taken in this way. A power source can be switched on by means of a switch 38, whereby the exposure control mechanism is then switched on.
s In Fig. 4 is a block diagram of one embodiment of the automatic exposure control system for the one shown in FIG. 1 shown camera reproduced. The brightness of an object is sensed by means of a conventional photo-sensing circuit 40, an amplifier 40/4 being connected to the output connection of a photoelectric element 4OC, with a diode 4OD having a logarithmic characteristic connected between its output and input connection. Furthermore, a device 41 for adjusting the photographic

ίο information is provided, which has the following devices: a device SV connected to the focusing screen 10 of the single-lens reflex camera for setting the film speed; means PSA connected to the diaphragm setting ring for setting the diaphragm value; a device PSS connected to the exposure time setting dial 24 for setting the exposure time; a setting device OPF for setting the fully open diaphragm on the lens; devices AMN and AMX connected to the markings 22 and 20, respectively, for setting the minimum and maximum aperture values; devices SMN and SMX connected to the markings 28 and 26, respectively, for setting a minimum or maximum exposure time; a device ST connected to the lever 36 for setting the self-timer time; and a setting device λ connected to the device 32 in order to set a program constant, for example by means of a digital switch, etc.

Further, a gate circuit 41 is connected C to the output terminal of the switch, while the output terminal of the gate circuit 41G is connected to a computing device 42, so that the state of each of the aforementioned devices or switch in dependence on the output of a Folgest your circuit 43 transferred to the computing device 42 will. The status of each function in a camera is set by means of a function verification and setting circuit, for example the position in which a mirror is brought or predetermined recording conditions, such as photography with priority setting of the exposure time or aperture value. The circuit 44 has the following switches: a switch SW1, which is switched through when the trigger is depressed; a switch SW2 for storing and holding the optically sensed brightness of an object in a register; a switch SW3 to select either an automatic or a preset iris; a switch SHM, which is switched through when the mirror reaches its upper limit position; a switch SW5 which is turned on when a rear curtain reaches its rear end position; a switch SWS for selecting the priority exposure time setting; a switch SW7 for setting priority setting of the aperture value; a switch SW8 for selecting a fully open sensing operation; and a switch SW9 connected to the selector switch for selecting a fully automatic exposure.

Here, the output terminals of the switch are each connected to the gate circuit G 44.

Furthermore, the output terminal of the gate circuit 44C is connected to a gate circuit 45 so that the gate circuit 44G can selectively output the signal from each of the switches SW1 -SW9 to the gate circuit 45 in accordance with the output of the sequence control circuit 43. The switch SW 1 is designed so that it is locked in the off position when the exposure time and the aperture value are not displayed on the display devices SSD and APD to be described below. The conventional gate circuit 45 has a number of input and output terminals. A function verification or determination circuit consists of the aforementioned setting circuit 44 for function evaluation and the gate circuit 45. The sequence control circuit consists of an SCC determination circuit 43a for retrieving the address of a sequence control counter (hereinafter referred to as SC counter) which the address of the Command conversion circuit (hereinafter referred to as ROM circuit), and the aforementioned SC counter 43b and ROM circuit 43c. Instructions such as addition and subtraction instructions or designation instructions are also included in the ROM circuit to designate the address or part to or from which addition or subtraction is to be performed. If the output from the ROM circuit 43c is other than jump or branch instructions, the determination circuit 43a fetches the next address in the SC counter after the function commanded by the circuit 43c is completed; on the other hand, when a branch or branch instruction is issued from the circuit 43c, the output is fed back to the determination circuit 43a and an address of the SC counter 43b is called in accordance with the branch or branch instructions and the output of the gate circuit.

The operating time of the sequence control circuit 43 is controlled by means of a conventional circuit for generating the reference time. The circuit 46 has an input connection to which the output of a conventional clock pulse generator 47 is applied and a number of output connections. A computing device 42 has a circuit 42a for carrying out the calculation and an ACC circuit 42b which stores digitally represented data. Address designation command is selected, or to add or subtract any photographic information to or from the contents of the ACC circuit 42b when the arithmetic command and the location designation command are issued from the sequence control circuit 43. Furthermore, the computing circuit 42 has a known gate circuit for transmitting the data of the ACC circuit 426 to any register of the data storage device 48 or to any one of the display devices 49; In addition, the circuit 42a has a circuit for adding or subtracting the theoretical value “1” to or from the content of the ACC circuit 426 and a circuit for adding the values “1” or “0” (in the following the values "1" or "0" represent theoretical values) at any desired BIT of the ACC circuit 426.

The circuit 426 comprises a register of, for example, 5 BITS; in the following description this is

lowest BIT with ρ and each of the following BITS with q, r, s and t , respectively. Each register of the data storage device 48 has a register of 5 BITS in accordance with the circuit 420. The data storage device 48 containing the calculation result, the digital-to-analog converter 50 and the circuit 51 judging the calculation result are connected to the output terminal of the arithmetic unit 42, while the setting device 41 for the photographic information, the data storage device 48 and the sequence control circuit 43 are connected to input terminals of the arithmetic unit are connected. The data storage device has a number of registers, namely a register SSR for storing the exposure time, a register APR for storing the aperture value, a register BR for temporarily storing the calculation result and a register BVO for storing the brightness. A conventional comparator 52 has an analog-digital converter (hereinafter referred to as AD converter in such cases) which, together with the DA converter 50 and the computing device 42, converts the analog value of the photo sensing circuit 40 into the digital value. A display device 49 has a display device SSD for the content of the register SSR, a display device APD for the content of the register APR and a display device EVD for displaying the number of error steps EV and a gate circuit 49C to control the display devices in accordance with the output of the sequence control circuit 43 . In a drive or control circuit 53 are an excessive exposure indicator lamp, an insufficient exposure indicator lamp LM 2, a solenoid L 1 for automatically dimming the lens, a solenoid L 2 for raising a mirror, a solenoid L 3 for starting a front one Curtain, a solenoid L 4 for starting a rear curtain and a solenoid L 5 for folding down and flip-flops 1 to 7 are provided. The 1'lip-i'iGpS 1 L / i5 / SiUu ΓΓΐΐΐ uctTi

SiIgSaFiSCiIiUiJ uCT oCuaitüilg jj VCrL / üFiuGfi \ giCiCiiZCiiig! St CiFiC 1 GTSCi ia llung

53 G is provided, via which each of the flip-flops 1 to 7 is controlled with the output of the sequence control circuit 43. The sequence of functions is stored in a circuit 54 that stores the internal state. By means of a reset circuit 55, the contents of all registers and the flip-flops are cleared when the switch 38 assigned to the energy source is switched on. The computing device 42, the data storage device 48 and the sequence control circuit 43 etc. can be combined into one unit.

The operation of the circuit of FIG. 4 described; Furthermore, reference is made to FIG. 5.6 (a) and (b) as well as a table 1 reproduced below to explain the in the F i g. 6 (a) and (b) used Code referenced.

Table 1

30th

code

contents

When exchanging the content of DR and the content of all BITS of Acc.

The content of DR (BR, SSR. APR, S, PSA ... α, etc.) is assigned to the BITS of the Acc.
added; the content of DR is not changed.

The content of Acc is added to the BITS of DR to accommodate the content of
Renew DR.

The content of all of DR's BITS is mapped to or from the content of Acc
added or subtracted and the results are left in Acc . The content
from DR is not changed.

All figures (numbers) of the content of Acc are made 0 (zero ... same below).

All figures (numbers) of the content of Acc are made 1 (zero ... same below).

The BIT i of Acc is made 0 (/ = ρ ■ q ... t).
The BIT / of Acc is made 1 (/ = ρ · q ... t).

The content of Acc is subtracted from 0 to become Acc's complement
save and leave its content in Acc.

The content of SWi (/ = 1-9) is determined, and when the switch is off, the sequence flowing in the direction of the arrow is carried out, while,
when the switch is on, the sequence flowing in the ON direction is executed.

The content of the comparator 52 is filled, and when the output of the
DA converter 50 is smaller than the analog voltage output of the photo sensing circuit, the sequence jumps in the direction of the arrow in FIG.

DR - Apt DR - Apt Apt -DR Apt ± DR 0 - Apt 1 - Apt 0- Ai 1- Ai β- Apt

THE END

AT

40 45 50 55 60 65

continuation

contents

(XXXX J

Flip flops
TO ADJUST

Flip flops
RESET

If the figures (numbers) are moved on when adding or borrowing when subtracting in the arithmetic process that takes place in the
the previous step is carried out, the sequence jumps to the arrow marker 1.

If the BIT content of T of Acc (T = ρ ■ q ■ r · s ■ r ■ pt (all figures)) is 1,
the sequence jumps in the direction of the arrow marking.

Labeled to show continuity in the flow chart.
The flip-flops (n = 1-7) are set.

The flip-flops (n = 1-7) are reset.

/ S. y q P.

16 8 4 2 1

The arrangement of the entire BITS of Acc.

When the switch 38 is switched on, a reset signal is present at the output of the reset circuit 55. This clears all of the registers of the setting device 41 for the photographic information, the function verification and setting circuit 44, the gate circuit, the arithmetic unit 42, the control circuit 53 and the contents of the flip-flops after a certain period of time determined by the sequence control circuit has passed the value "1" is registered step by step in the circuit 42b of the arithmetic unit 42, while it is controlled by the gate circuit 45 and the sequence control circuit 43; the output corresponding to the digital value is converted into an analog variable by means of the DA converter 50. The analog output of the photo sensing circuit 40 and the converted analog quantity are compared in the comparator 52. The amount of light from an object is converted in the computing device 42 from an analog value into a digital value; In this way, the perceived amount of light BV is determined when the film sensitivity information SV soft, the device is set 41 to the switch SV, upon application of the output of the sequence control circuit 43 via the gate circuit 41G is transferred to the computing device 42, then in the Arithmetic means 42 performs an addition between the photo sensing value SV and the film sensitivity information SV, and calculates the exposure value EV (ie, BV + SV) = EV; the exposure value £ V is then transmitted to the register BR of the data storage device 48 together with the time control which is determined by the output of the sequence control circuit and stored.Based on this exposure value EV , the corresponding exposure time and the aperture value are then determined, as will be described below

The following describes each of the four photographing methods, namely, photographing with one priority exposure time setting, with a priority aperture value setting, photography according to a program and by hand.

(1) Photographing with priority exposure time setting, that is, when the exposure time is set in advance and the aperture value is automatically controlled (referred to as the route SSLC in Figs . 5 and 6 (b)).

When the switch SW6 is turned on for the exposure time and selection of the switch SW7 is turned off for selecting the lens aperture setting, a signal is given via the gate 45 to the sequence control circuit 43rd The content of the switch PSS, which sets the exposure time TV , is transmitted to the computing device 42 through the output of the circuit 45. When the output of the sequential control circuit 43 is applied, a subtraction is also carried out between the exposure time TV and the exposure value £ Vin of the arithmetic unit 42 and the aperture value AV is calculated (ie (EV-TV) = AV). At the same time, the content of the arithmetic unit 42 A V. The aperture value Λ 7 is transmitted to the circuit 51 evaluating the calculation result and compared with the minimum and maximum aperture value AMND and AMXD , which are the contents of the switches AMN and AMX of the setting device 41, which are via the computing device 42 have been transferred. If the calculated aperture value A ^ lies between the minimum and maximum aperture value, it is stored in the register APR and at the same time via the arithmetic

device 42 transmitted to the aperture value display device APD , where it is displayed. In this case, the value of the exposure time, which is the content of the switch PSS, is transmitted via the computing unit 42 to the display device SSD and displayed there.

On the other hand, if the subject is too dark or too light and the aperture value A V calculated by the arithmetic unit 42 is compared by the calculation result judging circuit 51, and if the value s A V is out of the range determined by the minimum and maximum aperture values, it will not to the display device APD of the register APR , but instead the content of the switch AMN or the switch AMX is transmitted from the computing device 42 to the register APR and stored there. That is, the content of the register APR becomes the previously set, marginal exposure value. Then, when the automatic operation switch SW9 is turned on, a signal is output to the sequencer circuit 43 through the gate circuit 45. When the output of the circuit 43 is applied, a subtraction between the content of the register BR and the content of the register APR, ie between the aperture value lying at the edge and the exposure value (EV-AMND) or (EV-AMXD) is carried out in the arithmetic unit 42 and in this way the exposure time is calculated. The calculated exposure time is then transmitted to the assessment circuit 51 and compared with the minimum or maximum exposure value SMND or respectively. SMXD compared, which are the contents of the switches SMN and SMX of the setting device 41, which have been transmitted via the computing device 42. If the value lies between the minimum and maximum exposure value, ie within the limit values of the shutter, then the exposure value TV is stored in the register SSR and at the same time transmitted to the display device SSD , Wö 6Γ äfigcZcigi WiFu.

That is, if the switch SW9 is switched on and the object brightness is compared to the set »! Exposure time is too light or too dark and if a corresponding exposure is not obtained even if the calculated aperture value is the marginal value, then the previously set exposure time is automatically set. If the switch SWS is then turned off after one of the peripheral aperture values has been set, the brightness of an object is sensed again and the exposure value EV based on the sensed quantity is stored in the register BR. That is, the content of the register BR is replaced by the new exposure value, ie ZfV by EV '. The above-described operations are then repeated with the new exposure value EV.

(2) Photographing with priority setting of the aperture value will now be described; i.e. if the aperture value is set in advance and the exposure time is controlled automatically (Fig. 5 and Fig. 6 (b)) • This option is called ASLC:

When the exposure time selector switch SW6 is turned off and the aperture value selector switch SW7 is turned on while the aperture value is preset on the switch PSA , photography is carried out with priority aperture setting in the following manner.

By turning off switch SW% and turning on switch SW7 , a Signa! Output via the gate circuit 45 to the sequence control circuit 43. When the output is applied to the circuit 43, the content of the switch PSA, which is set as the aperture value AV , is transmitted to the computing device 42. Likewise, when the output of circuit 43 is applied, the subtraction between the aperture value A. V and the exposure value EVm is carried out by the arithmetic unit and the exposure time TV is calculated (ie (EV-AV) = TV). The content of the computing device 42 then becomes TV at the same time. DLser exposure value TV is transmitted to the assessment circuit 51 and compared with the minimum and maximum exposure value SMXD and SMXD , which represent the contents of the switches SMN and SMX transmitted via the computing device 42. If the calculated exposure value TV are within limits SMND and SMXD, the exposure time TV is stored in the register SSR and n simultaneously over the Reci? Device 42 transferred to the display device SSD where it is displayed. In this case, the aperture value, which is the content of the switch PSA, is transmitted via the computing device 42 to the display device APD and displayed there is not obtained when the exposure time is set to one of the edge values, the preset aperture value is automatically set, and then the operations are performed as in the priority exposure time setting

(3) So-called program photography will now be described, that is, the predetermined combination of the aperture value of a lens and the exposure time is set as the calculation result of the brightness of the object and the film speed is automatically controlled (this is shown in Fig. 6 (b) with the flow PROG ).

Based on the F i g. 7, the principle of exposure control in program photography will first be described. In Fig. 7, the exposure time is plotted on the abscissa (on the X-axis) and the aperture value on the ordinate (on the Y-axis). The well-known diagram of the exposure value (EV ^ characteristics is made up of the exposure values EVO, EV \, EV2 ... EVn . PRG 1 is a program curve and P 1 is a straight line with a slope ac. The straight line P 1 can be expressed by:

Y = ocX (1)

the above-mentioned straight line EVX of the exposure value characteristics can be expressed by:

Y = -X ₊ (EVy) (2)

If the quantities AT are calculated from equations (1) and (2), we get: Ij

i I

(4) 1

d. It can be seen from equations (3) and (4) that the exposure time can be obtained by g

to the output EVy of the photo sensing circuit by the sum of the previously set constants λ plus the §

Constant 1, ie {x + 1) is divided, while the aperture value Y as the product of the exposure time obtained = 8

and the constant λ is obtained. It can thus be seen that the values (X, Y) in program photography ρ

can be obtained by inputting the constant χ into the arithmetic unit 42 so that in this, §j

based on the exposure value EVy, multiplication and division are performed. ψ,

According to the invention, the calculation shown in equation (3) is performed by the arithmetic unit r,

42 and the data storage device 48; after calculating the value X, ie the exposure YY

time is then continued as in the procedure with priority exposure time setting and then w

the same calculation is carried out as in the procedure listed under (1). In this way, the '

corresponding exposure value calculated. That is, when both the switch SW6 for the exposure time selection and the switch SW7 for the aperture value selection are opened, the signal via the

Gate circuit 45 to the sequence control circuit 43 and the output of circuit 43 to the arithmetic unit;

tion <2 delivered. As a result, the exposure value EV T sensed by means of the photo sensing circuit 40 is then transmitted via the computing device 42 to the register APR and the constant cc, which represents the content of the ^: k, switch χ , is registered in the computing device 42 after the value "1" there added: "^;

has been; d. That is, at this time, the content of the arithmetic unit 42 becomes (λ + 1). j i

The exposure value EV stored in the register APR is then determined by the content (x + 1) of the computation Sj

device 42 divided; This division is in a known manner by means of the register in April and Recheneinrich-: '■ processing 42 performed as a result of this division the exposure value TV of the computing device 42 is transferred prior year to the register SSR and stored Likewise, the aperture is in the computing device 42 - ■ ':;

worth AV, based on the exposure time TV, over the way as when photographing with preferred ί ■! Exposure time setting set; the aperture value Λ V is transferred to the register Apr and stored '\ ■ and at the same time the same aperture value V and A are transmitted, the exposure value TV to the display means APD and SPD, where they are respectively angezsigt. ; Since three photographing methods have now been described above, the fourth method will now be ■; -.

photographing by hand is described (this is shown in Fig. 6 (b) under the flow chart MANL- '

hen).

When both the switch SW6 and the switch SWi are turned on, the content of the switch PSS of the setting circuit 41 is transmitted via the arithmetic unit 42 to the register SSR and at the same time to the display device SSD. When the output of the sequence control circuit 43 is applied, the exposure value and the content of the switch PSA are added in the arithmetic unit 42. That is, the calculation PSS + PSA = PEV is carried out. The content of the register BR, ie the exposure value EV, and the preset exposure value PEV are compared with each other and the number of error steps above and below is calculated and displayed
With the method described above, a suitable aperture value and the exposure time are calculated and stored in each of the registers A PR and SSR

If the switch SW2 connected to the button 34 for automatic exposure measurement is not closed, the calculation of a corresponding exposure value in the above-described method is carried out at a certain time interval (each at an interval of several tens of msec) which is determined by the sequence control circuit; Here, the content of each register APR and SSR is renewed and stored again. Even if the switch SW2 is closed, the corresponding exposure value is stored in each register APR and SSR immediately before closing, but after closing, even if the object brightness changes, the content is stored the register no longer renewed

Next, when the shutter release switch 5Wl is turned on, the mechanism of a camera is controlled with a sequence shown in FIG. 2 is shown according to CTRL . First, the time of a self-timer set on the switch ST is transmitted to the arithmetic unit 42 and counted; After the counting, the amount of light BVi is then sensed photoelectronically. The sensed value BVX is then stored in one of the registers not shown in the drawing in the data storage device 48. If the switch SW3 is switched on during the automatic dimming, the flip-flop F provided for this purpose is activated. F3 is set and automatic dimming has started.

During automatic dimming, the amount of light from an object that still passes through the aperture is felt and further dimmed until the perceived amount of light is BCX -APR . As stated above, when the sensed amount of light becomes BV2 , that is, BC 1 -APR - BV2, a reset signal is output from the sequencer circuit and the flip-flop F.F3 is reset; in this way the stopping down is then ended

Thereafter, if a preset shutter mechanism has been used as usual, the switch SW3 is switched over during the automatic dimming. As a result, the aperture value is set in accordance with the APR register.However, it is possible that the preset aperture value is not set to a suitable aperture value due to a mechanical error in the automatic dimming mechanism.

is assumed governed according is to the invention when the preset aperture value is completed, again performed based on this aperture value, a photoelectric measurement The exposure time is then measured at that point in time based on the measured amount of light BV2 and the result of calculation is in the register SSR saved This means that if the aperture value is set by the preset automatic dimming mechanism, the calculated exposure time is corrected accordingly

When the above-described operation is completed, a signal to raise the mirror is output from the sequencer circuit 43. This sets the flip-flop F.F4 and the solenoid L 2 is excited, whereupon the mirror flips up; Then, if after raising the level of the switch SW is turned on 4, the flip-flop F.F3 is set the solenoid LZ energized and the forward curtain moves Thereafter, the contents of the register SSR is counted and then the flip-flop RF6 by the output the sequencer circuit 43 is set. This energizes the solenoid L 4 and then moves the rear curtain. When the rear curtain reaches its prescribed end position, the switch SWS is turned on and the flip-flop FS1 is set. This then energizes the solenoid L 5 and the mirror again folded down; this then ends the recording

If there are any specific numbers due to a photographer's choice for the fade-down number and the is Exposure time are not set, the system works in program mode. Though taking photos is selected according to the program to finally by automatic selection of a predetermined combination of Aperture value and the exposure time for the lens as a result of the calculation of the object brightness and rjer Film speed to obtain an appropriate exposure, this calculation method is used below based on Fig. 9 described.

In Fig. 9, the exposure time 7V is plotted on the abscissa and the aperture value Λ κ on the ordinate. Since the value Tv is equivalent to the squinting ranges of the numerical code from "000" to "240", the zero point of the abscissa in the numerical code is set to "000", ie on the peak value "-8", in order to initiate the practical calculations. The exposure value Ev is also shown as a straight £ V line, so that the points at which the sum of the aperture value Λ ν and the exposure time Tv in the numerical code become the same are connected to one another in the range from EvOOOs to 370g ff. The straight Ev line therefore has a position which is determined by the size of the exposure value Ev obtained from the photoelectric information. In the diagram, the straight lines Pq to Pt have an inclination from «o to aj and the straight line is defined in the numerical code by:

30 Av - «" Tv (15)

There is also the relationship expressed by the equation

Tv - Ev-Av (16)

can be obtained from the equation (14), the following reference equations can be obtained from the equations (15) and (16) are obtained:

(17)

Tv = - £ v (18)

as a result, a predetermined combination of the aperture value Av and the exposure time Tv can be obtained in comparison with the exposure value Ev obtained from the photoelectrically measured data by setting Ct _n accordingly. In this example, the angles of inclination α " to αη de-. Straight line so P ₀ to Pi given by 0.1 / 7.1 / 3.3 / 5.1.5 / 3.3.7 by adding the expression

equivalent value is selected by the input device PRCNaIs the program constant in whole numbers from 0 to 7; consequently, a photographer's choice can be made to some extent even in a program mode by changing the combination of the aperture value Λ ν and the exposure time Tv.
Then, if the program constant is represented by PCA / and inserted into the following equation: & o

= _lfs_ (19)

l + a "

the fade-out number can be determined by the following calculation:

Av -PCN- ^ - (20)

Although in the foregoing, whether or not the f-number A vs determined in this way is set between the maximum and minimum aperture values AMX and AMN by a photographer, if the aperture value Av obtained from a calculation exceeds the maximum aperture value AMX , the latter becomes is substituted into the equation (16) as the determined aperture value Av , while the minimum aperture value AMNm is substituted into the equation (16) when the calculated aperture value Λ ν is smaller than the minimum aperture value AMN. In this way, the exposure time Tv for correct exposure can then be obtained. Although the maximum and minimum values are used for the exposure time Tv , if the exposure time Tv obtained by calculation is not within the set maximum and minimum exposure time TMX or TAiN, the exposure cannot of course be taken with the correct one

ίο exposure to be carried out. The aperture value Av and the exposure time Tv required for proper exposure can therefore be finally determined by each of the above-described modes.

If a correct exposure is to be obtained without either the aperture value or the exposure time having been set, i.e. so-called program photography is to be initiated, then both the aperture ring 18 and the exposure time setting disc are set to the "AUTO" position without special values are chosen; The maximum and minimum exposure times TMX and TMN as well as the maximum and minimum aperture value AMXand AMN are set.Furthermore, a program constant PCN, which represents an element to determine the combination of the aperture value Av and the exposure time Tv , and both values are calculated automatically

Now only the maximum and minimum values are to be set both for the aperture value Av and for the exposure time Tv . At this point in time the control flow passes over into the program flow, and the calculations, such as

Av = PCN ^ -

then take place with the program constant PCN, which is entered with the setting device 32, and with the exposure value Ev, which is previously obtained on the basis of the photoelectric measurement; in this way the aperture value becomes A behavior. The thus obtained diaphragm value A ν is then compared with the arsprünglieh set minimum aperture value AMN, and if it is smaller than the value of AMN, the minimum aperture value AMNaIs the aperture value used when it is greater than the minimum aperture value AMN, it will be with the maximum aperture value originally used AMX compared and if it exceeds this, is det maxiiE-de aperture value AMX used as the aperture value as stated above, is then obtained, the aperture value Av, which according to the predetermined program constants PCN is computed within the Ben "ehs between the originally set maximum and minimum aperture value The control flow then passes into the flow for priority aperture value setting and the exposure time Tv results from the fact that the obtained aperture value Av is used as the set value If the obtained exposure time Tv is not between the originally set maximum and mi is below the minimum value, the control flow returns to the starting point, as stated above. If fully automatic operation is selected by means of the switch, the control flow changes to the flow for priority exposure time setting, the set maximum or minimum value of the exposure time then being used as the originally set exposure time.

In the event that the switch for fully automatic operation is selected, that the exposure time or the aperture value for a corresponding exposure cannot be obtained under the set conditions, and that under these circumstances there is a mode change compared to the exposure value Ev obtained by the photoelectric measurement the flip-flop is reversed and reset both in the data flow for priority aperture value setting and in that for priority exposure time setting; the control flow then returns to the starting point based on the assessment of the on / reset status of this flip-flop.

As mentioned above, when the aperture value A ν and the exposure time Tv required for proper exposure cannot be obtained within the set conditions and the control flow returns to the starting point, an underflow or overflow display is made and the photographer can determine this in the search field; As a result, he can either change the conditions used or switch to manual operation, whereby an aperture value A ν and an exposure time Tv can then be obtained at which a recording can be initiated. If a corresponding exposure becomes possible by changing the conditions under the conditions now set, the above-mentioned underflow or overflow display disappears.

In addition 12 sheets of drawings

Claims (2)

Patent claims: 1. Electronic exposure control device for a camera, with a first setting device for Selection of an automatic exposure with aperture preselection, with a second setting device for Selection of an automatic exposure with time preselection, as well as with an exposure control circuit that automatically determines the exposure time if the automatic exposure with aperture selection by the first setting device is selected, and which automatically determines the aperture if the automatic Exposure with time preselection is selected by the second setting device, characterized in that that the exposure control circuit (43 in Fig. 4A and 42, 48, S1, 53 and 54 in Fig. 4B) one ίο Exposure value generated for a further programmed operating mode, if the automatic exposure is with Aperture preselection by the first setting device (24 in FIG. 1) and at the same time the automatic exposure is selected with time preselection by the second setting device (18 in FIG. 2) 2. Electronic exposure control device for a camera according to claim 1, characterized in that that the first setting device (24 in FIG. 1) has a first setting position ("AUTO"? 24 in FIG. 1) for identification automatic attention with aperture preselection and a second setting position (60 to 2000; 24 in F i g. 1) for selecting the exposure time has that the second setting device (18 in FIG. 2) has a first Setting position (»AUTO« 18 in Fig. 2) to identify the automatic exposure with time preselection and a second setting position (1.4 to 22; 18 in Fig. 1) for selecting the aperture value, and that at Adjustment of the first setting device (24 in FIG. 1) and the second setting device (18 in FIG. 2) their first setting the exposure control circuit generates the exposure value