DE2743779B2 - Aperture calculator for computer flash units - Google Patents

Description

The invention relates to an aperture calculator for computer flash units according to the preamble of Claim 1.

Computer flash units only emit the amount of light that is required to properly expose an image. For this it is v, necessary to set the film speed and the camera aperture to the flash unit, because these two factors are decisive for the amount of light emitted.

From DE-OS 17 72 940 an aperture calculator bo known, in which both film speeds and distances are set mechanically and which result from These settings can be read off the working panels on a scale. The setting the distances (or the apertures) is done with this known aperture calculator with the help of a switch lever, the light output of the flash unit is changed when this switch lever is moved. The display of the Working panels are made with numbers on a disc. In this known aperture calculator are one A series of distance values always opposed to a series of aperture values. The display of the straight valid aperture or distance value is given by corresponding indices. It is there possible that the user is unsettled by the many digits and a wrong aperture value reads In addition, the digits are relatively small, as the scales cannot be made arbitrarily large. This makes reading difficult, especially in poor lighting conditions.

From DE-OS 19 17 934 an aperture calculator is also known for computer flash units, in which the value of the distances, film speeds and Aperture corresponding digits are attached to scales. In this known arrangement is each only one aperture value is always displayed in a small window. Here too, the digits are relatively small because the Scales cannot be made arbitrarily large.

From DE-OS 25 52 359 a camera is known in which the photographic exposure values by a digital display device for display in the viewfinder of the camera. With this well-known Arrangement are the digital digit display elements via a photometric arrangement, the one Analog-to-digital converter includes, driven. However, there is no indication in this known arrangement on how the exposure parameters film speed to be taken into account in an aperture calculator and distance can be entered.

The object of the present invention is to create an aperture calculator for computer flash units, which guarantees reliable reading of the relevant data with little switching effort.

The advantage achieved by the invention is in particular that by means of a simple to realizing arrangement for generating signals for controlling digital digit display elements a better readability compared to the known aperture calculators with scales due to strong protrusion of the most important information is obtained, thus avoiding mix-ups and thus the risk of Operating errors are reduced.

Based on an embodiment shown in the drawing, the underlying of the invention is intended Thought to be explained in more detail. It shows

F i g. 1 an aperture calculator with a digital working aperture,

F i g. 2 shows a first circuit arrangement for the digital display of the work panel,

F i g. 3 a second circuit arrangement for the digital display of the work panel,

F i g. 4 shows a third circuit arrangement for the digital display of the work panel,

F i g. 5 shows a fourth circuit arrangement for the digital display of the work panel.

In FIG. 1 shows a plate 1 which is arranged on the rear side of a computer flash unit. This plate 1 essentially has two areas, namely an area 2 for the operation of the flash device without a computer and an area 3 for operating the flash unit with a computer. Area 2 is through a Sliding window 4 covered, so that the scales behind it, which can be designed as in the Braun flash units available on the market 28 BVC, 34 VC and 40 VCR, are not recognizable. These Scales are indicated by the dashed circle 5 only

indicated On the lower frame of the plate 1 is a socket 6 for receiving a Charging plug, an on / off switch 7 and a button 8 for manual triggering of the flash unit.

The right area 3 of the plate 1 has a slide switch 9 for setting the 3 distance range on, the computer being switched off in the lowest position 0 of the slide switch 9 the next position, which is denoted by 10, the close range (z. B. 0-13 m) is set, while in the ι ο following position marked 11, the middle range (e.g. 1.5-4.1 m) is set and in the last position, which is labeled 12, the far range (4.5-30 m) is set in a window 13, which is arranged above the distance information, are z. B. Liquid crystals for the digital display of the Work panel provided.

Before a flash exposure, the sliding window 4 is moved to the right with the aid of a projection 14 so that the scales are released. The film speed can now be adjusted in the usual way. When the slide switch 9 is in position 0, it is possible to take flash photos without a computer in the usual way.

If the sliding window 4 is now pushed to the left and the sliding switch 9 is brought into position 10, so there is computer operation in the vicinity. The set film speed can be changed by a Opening 15 in the sliding window 4 can be seen. Due to the given values of the film sensitivity and the distance range, the aperture that is on the camera is automatically calculated is to be set. This aperture is displayed in the window 13, with the help of additional identifiers, z. B. Point 16, it can be displayed whether at J intermediate values of the film speed set the exact aperture value tends to increase or decrease.

If a test flash is triggered now, you can use a light emitting diode 17 are displayed as to whether the energy present in the flash unit is sufficient to the to meet the set conditions. This is important because in the case of bounced light a great deal of light can be absorbed by dark bodies, so that the existing light energy cannot sufficient to provide proper exposure under the circumstances.

In Fig.2 tine circuit arrangement is shown, which shows how the screen can be displayed digitally with a liquid crystal element, so with the help of a resistor 18 and a Zener diode 19, which are connected in series to a DC voltage U , a stable reference voltage is first Uref is formed, which is tapped between the resistor 18 and the Zener diode 19. This reference voltage Uref is fed via a switch 20, which is in a first switching position, to a voltage divider, which consists of two resistors 21 and 22. A connection leads from the connecting line between the two resistors 21 and 22 to the "> non-inverting input of an operational amplifier 23, in whose feedback branch two variable resistors 24, 25 are connected. From the inverting input of the operational amplifier 23, which is connected to the aforementioned variable resistors f> 5 24, 25, a connection to ground also leads via a resistor β6. If the voltage rait Ue present at the non-inverting input of the operational amplifier 23 is designated, then this is the output voltage of this amplifier

Ua =

Resistance 74 + resistance
~~ Resistance 26

The variable resistors 24 and 25 are assigned to the film sensitivity or the distance So that certain discrete film speeds or distance ranges can be set exactly can, it is possible to provide different locking positions in which the slide of the resistors can snap into place.

From the formula given above, it can be seen that the output voltage Ua increases the larger the resistor 24 or the resistor 25 becomes. The resistor 24, which is assigned to the film sensitivity, for example, is thus larger if there is a smaller film sensitivity, while the resistor 25, which is e.g. B. associated with the distance, becomes larger as the distance increases. By changing the resistors 21 and 22, the circuit arrangement can be adapted to different lightning guide numbers.

The output voltage Ua is now fed via a resistor 27 to the inverting input of a further operational amplifier 28, at the non-inverting input of which there is a resistor 29 which is connected to the reference voltage Uref and a resistor 30 which is connected to ground whose inverting input connects.

The operational amplifier 28 now forms a voltage which is proportional to the difference between the reference voltage Uref and the output voltage Ua , the gain factor V being formed from the quotients of the resistors 30/29 and 31/27. The voltage is thus at the output of amplifier 28

Up = V (U _Rer -Ua)

at. The voltage Up can be adapted to the input voltage range of the subsequent analog-digital converter 32 by means of the amplification factor V. This analog-to-digital converter supplies, for example, a BCD signal to a supply stage 33 which contains a decoder and a driver in order to control the liquid crystals.

Appropriately, only the aperture values 1 to 32 are displayed directly, while intermediate values, e.g. B. + '/ 3 f-stop or -' / 3 f-stop, through dots 16 (Fig. 1) being represented.

With the switches 20, 35 connections can be made to an external camera system that e.g. controls flash units with the help of a microprocessor. The connection to the The camera system is produced by bringing the switches 20, 35 into the positions shown in dashed lines will.

FIG. 3 shows a variant of the circuit arrangement according to FIG. 2 is shown, in which the output part is changed, while the input part until the output of the voltage Ua with the arrangement of the F i fe. 2 matches. The components of the input part are therefore shown in FIG. 3 summarized for device 36.

The voltage Ua passes from the output of the device 36 to a voltage-frequency conversion

zer 37, which delivers a pulse train proportional to the voltage with the frequency. The pulses are fed to a counter 38 which is incremented by a clock generator 39. Within predeterminable intervals that z. B. be marked by stopping the clock generator 39 , the count of the counter 38 is called up and a decoder and driver circuit 40 which controls a liquid crystal display. The counter readings of the counter 38 can possibly also first be stored in an intermediate memory and only then given to the decoder and driver 40 . When the meter reading information is transferred to the buffer, the meter reading is deleted. The combination counter / memory is known per se and is available on the market as a uniform module.

The with the circuit arrangement according to FIG. 3 advantages achieved consist especially in that the display value fund a clock signal is determined by a frequency, resulting in an easier adjustment option. In addition, only one supply voltage is required.

4 shows a variant in which a binary-coded printed circuit board 41 is provided which, for. B. has five tracks for the film sensitivities 9 ° DIN to 39 ° DIN, which corresponds to thirty-one values. This printed circuit board 41 is mechanically displaceable according to the number and the values of the adjustable work panels, the distance ranges also being taken into account.

The printed circuit board 41 has, for. B. five lines 42-46 and thirty-two columns I-XXXII, of which the five fields of a column are simultaneously picked up by grinders 47-51. With five taps, 2 ⁵ = 32 values can be tapped, so that thirty-two columns are provided if all options are used.

To adjust the distance and to adjust the film speed, the printed circuit board 41 is shifted horizontally, in such a way that a higher film speed causes a shift to the right and a smaller distance a shift to the left. The resultant of the two shifts is then the value that is sampled by the grinders 47-51.

This resultant is now sent via the services 79-83 to a ROM memory 84 which, as it were, contains an assignment table and outputs a digital display value which is permanently assigned to the respective resultant

A connection leads from this memory 84 to a driver 85 which controls a liquid crystal display 86 with the indicated display value.

For this adaptation of the flash device to an automatic camera with flash control, a digital-to-analog converter 87 is also provided, the input of which is connected to lines 79-83 and which controls a camera with its output.

The advantage of the embodiment according to FIG. 4 is that the film speed and the ^r > distance can be easily adjusted and that the display values are not adulterated by conversion errors. A ROM memory could be circumvented by providing a printed circuit board which is encoded in BCD code. However, this would be more

tu require slider tracks than with the arrangement nac!> Fig. 4. In addition, the digital-to-analog converter would be which one should supply a voltage to the camera cannot be realized with simple means.

In Fig. 5 a circuit arrangement is shown,

Ii which differs from the circuit arrangement of FIG. 4, inter alia, in that it has a different Prinlplaue SS. This printed circuit board 88 has six lines 89, 90, 91, 92, 93, 94, which - from bottom to top - have the values 8, 4, 2, 1, ² Ii, U) . Any 6-bit value

2 » corresponds to a film speed value, whereby these values can be represented in 1/3 steps. -

The ends of sliding contacts 95-100 rest on this printed circuit board 88, specifically in such a way that each of the sliding contacts 95-100 is one line of the printed circuit board

r> 88 is assigned. Sliding contacts 95-100 and printed circuit board 88 can be moved relative to one another. If a higher film speed is to be set, the sliding contacts 95-100 are shifted to the left, while with the setting a lower one

«Ι Distance the printed circuit board 88 is shifted to the right.

The values tapped with the aid of the sliding contacts 95-100 are fed to a read memory 101 , which stores the tapped digital values

r> each assigns a specific aperture value and feeds this aperture value (for example 1, 1.4, 2, 2.8...) to a driver 102 which controls a display device 103 .

The values of the sliding contacts 95-100 are also

is also fed to a digital-to-analog converter 104 , which controls a camera (not shown).

Since the digital-to-analog converter 104 can only process binary weighted signals, the 6-bit code of the sliding contacts 95-100 is converted into a 7-bit code with the aid of an additional OR circuit 105

■ «) formed with the weights 8, 4, 2, 1, '/ 2,' / 4, Us , where now the aperture values F + U3 by the approximation F + Ά + '/ β and the values F + ² /) by the Approximation F + V2 + U & are shown. Since '/ 4 + Ve = 0.375 and' / 2 + '/ β = 0.625 one recognizes that the

■> o Approximation caused errors less than ± 0.042 F-stops is.

The logical assignment between the signals of the sliding contacts 95-100 and the signals present at the input of the digital-to-analog converter results from the following table

05
8th

O ₄

"3 2

² ii

O O O O O O O O O O O O O O bj - 0 \ I. O O O O O L. O O O O O L. L. b, = a ,. 2 O O O O L. O O O O O L. O 1 6 (i = fl | i'fl ( 3 O O O L. O O ö O O L. O O O 4th O O O L. O L. O O O L. O L. L. 5 O O O L. L. O O O O L. L. O L.

For this purpose 3 sheets of drawings

Claims (6)

Patent claims: 1. Aperture calculator, for computer flash units, in which both film sensitivities and distances are adjustable and in which the working apertures resulting from these settings can be read, characterized in that the display of the working apertures is done by digits, which are represented by electrically controllable components, that a coding disk (41) and grinder (79-83, 95-100) are provided, each of which can be displaced relative to one another according to the film sensitivities or the distances, and that the signal levels of the grinders (79-83, 95-100) via conversion directions (32, 33,104) control the digital display (34). 2. Aperture computer according to claim 1, characterized in that a digital-to-analog converter (87) is connected to the wipers (79-83), the output of which leads to an automatic camera. 3. Aperture calculator according to claim 1, characterized in that the coding disk is set to five Rows (42-46) and thirty-two columns (47-70) consists 4. Aperture calculator according to claim 1, characterized in that the coding disk (88) has six lines (89-94) , the valence of which is' / 3, ² h, 1, 2,4,8 5. Aperture computer according to claim 1, characterized in that a digital-to-analog converter (104) is connected to the grinders (95-100) , the output of which leads to an automatic camera, the code of the grinder (95-100) is converted into a binary weighted code prior to input into the analog-to-digital converter (104). 6. Aperture computer according to claim 5, characterized in that an OR gate (105) is provided for converting the code, which produces new information from two bits of the grinder code, so that the last three digits of the new code have the weighting ' / 2, '/ 4, ve have.