JPS60143319A - Electric automatic flash system of camera - Google Patents

Abstract

PURPOSE:To obtain an electric automatic flash (AF) function which obtains proper exposure by turning on a stroboscope synchronizing with the opening timing of a shutter blade even when a photographic condition change by providing a correcting value input means which corrects the variation of photographic conditioner. CONSTITUTION:Film sensitive information is preset in a counter 4 which counts an aperture detection value from an aperture detecting circuit 19 through a switch means 11. Then, a counter 16 in which a count-up value is set through a camera sequence control circuit 12 and D type FF13 corresponding to the variation of photographic condition is supplied with the number of pulses which corresponds to a set value from an oscillator 15. Those pulses are supplied to the counter 4 through an OR circuit 18 as well and the count contents of the counter 4 are corrected according to variation of photographic conditions. Then, the stroboscope is turned on according to the shutter blade opening based upon an aperture value corresponding to photographic distance from a decoder to attain the AF which controls proper exposure even when the photographic condition changes.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electric flash auto system for cameras that is capable of determining strobe light emission timing by making corrections corresponding to fluctuations in photographing conditions.

Conventionally, full-flash type strobes used in strobe photography are equipped with means for detecting the aperture position of the shutter blades, and the aperture value determined from film sensitivity information, shooting distance, and guide number of the strobe is detected by the detection means. Electric flash auto (also called electric FA) detects the opening movement and fires a strobe at the same time to obtain the appropriate exposure.
has been proposed in Japanese Unexamined Patent Publication No. 58-42033.

In addition, as an improved version of this model, on the premise that the strobe light is emitted under certain conditions, the aperture detector outputs the aperture from the aperture detector to a counter preset with the decoder output based on the shooting distance information and the film sensitivity information. One conceivable method is to determine the timing of strobe light emission and obtain proper exposure by comparing the output of counting pulses corresponding to the value.

However, in recent years, even in cameras with lens shutters, if the focal length of the photographic lens is as short as 28 to 40M, it is not possible to take a large picture of the subject unless the camera is brought close to the subject. Cameras and the like with two focal lengths have been commercialized. For this reason, it has become possible to eliminate the above-mentioned drawbacks by switching the focal length, but the diameter of the entrance pupil of the photographing lens is the same, and therefore the aperture value indicated by the detection section that detects the aperture position of the shutter blade. As the aperture value changes due to this focus switching, the aperture value no longer corresponds to the same aperture value, making it impossible to use the electric FA system as described above.

Additionally, as the sensitivity of film has become higher, the amount of light emitted by conventional strobes is too large, so when shooting with strobes at short distances, the exposure is too large even at the minimum aperture, making it impossible to obtain an appropriate exposure. there were. Therefore, the amount of light emitted by the strobe may be changed in stages according to the film sensitivity (or distance), but in this case, it becomes impossible to use the electric FA system as described above. Furthermore, there may be cases where the photographer wants to compensate for the exposure caused by flash photography, taking into account light reduction by using a filter or harmonization between the flash light intensity and the surrounding light intensity.However, in these cases, the electric FA aperture Since this cannot be done without correcting the calculation factor, it is not possible to use the conventional electric FA as described above.

Invention 1 In view of the above-mentioned points, this invention has been made to eliminate the above-mentioned drawbacks, and by providing a means for inputting a correction value for correcting fluctuations in photographing conditions in an electric flash auto of a camera, photographing conditions can be adjusted. The purpose of the present invention is to provide an electric flash auto system for a camera that can perform strobe photography even when there is recoil.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a specific embodiment of an electric FA calculation correction circuit according to the present invention. In Fig. 1, reference numeral 1 denotes a shooting distance information generating circuit, which inputs distance information measured by a distance measuring device (not shown) into a counter and outputs it as 4-bit distance information. The distance information is converted by the decoder 2 into comparison information such as the actual distance of the distance information, aperture information corresponding to the aperture value derived from the guide number of the strobe, and film sensitivity information at the time of the guide number. 6 is a magnitude comparator, which outputs the output of the counter 4 which outputs a value counted based on film sensitivity information, bone fluctuation correction information due to changes in imaging conditions, and aperture information, and the above comparison information. The output of the decoder 2 is compared with the output of the decoder 2, and when the former output matches or exceeds the latter output, a "high" level (hereinafter abbreviated as "H" and "L") signal for strobe light emission is output. The counter 4 includes five D-type flip-flops (hereinafter abbreviated as D-FF) 4a~
When two pulses are input to the clock pulse input terminal (hereinafter referred to as CK line terminal) of D-FF4a, which outputs the signal of the least significant bit, the output is It is configured to go up one level. The D-FFs 4a, 4b, 4c, 4a, and 4e are configured to output to the magnitude comparator 6 from their respective Q terminals in this order starting from the lowest order.

Reference numeral 11 denotes a switch means for inputting film sensitivity information according to a code provided on a film cartridge used for photographing, the input side of which is connected to the power supply side Vc;
When the circuit is activated, it becomes "H"'L.

Reference numerals 8 to 10 are pull-down resistors provided on the output side of the switch means 11, 5 to 7 are AND gates, the - input terminal is commonly connected to the camera sequence control circuit 12, and each of the other input sides is connected to a switch. They are individually connected to the terminals on the output side of the means 11.

Note that the AND gates 5 to 6 input the film sensitivity information of the code provided on the film cartridge to the D-FFs 4b to 4d of the counter 4, respectively, only when the "H" and "L" signals are input from the camera sequence control circuit 12. Connected to input.

16 is a D-FF, which inputs the Q output of D-F'F4d of the counter 4 which inputs the film sensitivity information, and when this Q output is H"L, that is, when the film sensitivity is very high,
One pulse from the camera sequence control circuit 12 is input, the Q output is set to "H" and L, and a signal to be corrected for fluctuation is output. 16 is a counter, which is designed to set the maximum value to be counted, and when the counted value reaches the set maximum value, it outputs a "H" and "L" signal, and the input side outputs this output to an inverter gate. The output inverted by 17, the output of oscillator 15, and the Q output of D-FF1 are inputted via AND gate 14.

Further, the output of the AND gate 14 is inputted to the CK line terminal of the D-FF 4a of the counter 4 via the OR gate 18, so that fluctuation correction information is input to the counter 4 manually. Reference numeral 19 denotes an aperture detection circuit which outputs an aperture pulse for aperture detection obtained from the operation of the shutter blade using, for example, a slit provided in the shutter blade and a fixed photointerrupter.
Aperture information is input to the counter 4 by inputting it to the CK line terminal of the D-FF 4a of the counter 4 through the input terminal 8.

20 is a D-FF that latches that the aperture is open and outputs a permission signal for strobe light emission from its Q terminal;
On the input side, when the circuit is operating, "'H" and "L" are manually input, and the aperture pulse from the aperture detection circuit 19 is input to the CK line terminal. 2
1 is an AND gate that manually compares the Q output of the D-FF 20 with the comparison result of the magnitude comparator 6, and when the aperture opens and the output from the magnitude comparator 3 becomes "H" and "L" as described above, the strobe trigger circuit is activated. "H" and "L" to operate 24 and fire the strobe.
The allowable signal is outputted to the strobe trigger circuit 24 via the OR gate 22. 26 is a shutter abort/second time signal generation circuit, which is composed of a counter, etc., and counts at the same time as the film exposure starts, outputs "'H" and "L" at a predetermined time, and sends this signal to an OR gate. 22 to the strobe trigger circuit 24 to cause the strobe to emit light. This means that even if the shutter is opened and all aperture pulses are output from the aperture detection circuit 19, when the output of the magnitude comparator 6 does not become "'H" or "L", the strobe trigger signal will not be output as it is. Therefore, the shutter abort time signal generating circuit 26 outputs this trigger signal after a predetermined time to cause the strobe to emit light.

Note that the power is turned off when the shutter release operation is completed, and when the shutter release is pressed to the first stroke, the power is turned on again to this circuit, and this circuit is cleared from the initial state by a power-up clear circuit (not shown). The state is now reset.

Figures 2 (a), (b), and (c) are specific numerical examples of film sensitivity information, aperture information based on aperture pulses, and distance information, respectively, and are based on the method of the electric FA calculation correction circuit of the present invention shown in Figure 1. used for. Here, Fig. 2 (a) shows the Q output when the filter and sensitivity information are input to the counter 4, and Fig. 2 (b) shows the count value of the aperture pulse (2 In Fig. 2 (C), the 4-bit information from the left indicates the output of the shooting distance information generation circuit 1, and the 5-bit information in the center indicates the output of the decoder 2. The signal on the right shows the distance from the camera to the subject. The comparison information output from the decoder 2 includes the number of aperture pulses shown in FIG. 2(b), which corresponds to the aperture value when the strobe guide number is divided by the effective distance, and film sensitivity information based on the reference, for example. If it is 15O100, the information added with oo too is the comparison information from the decoder. In the case of this example, the guide number is 10 and the film sensitivity information is 15O100.
This is the output of the decoder when .

Next, the operation of one embodiment of the present invention will be described with reference to FIGS. 1 and 2. When the release button is pressed to the first stroke, the electric FA calculation correction circuit shown in FIG. 1 is reset. Next, camera sequence control circuit 1
2 to 1 pulse "H" and "L" output is AND gate 5 to 7
As a result, film sensitivity information corresponding to low 1 of the film sensitivity on the film cartridge is preset to the D-FFs 4b to 4d of the counter 4. In addition,
Here, the reason why the film sensitivity information is not preset in the D-FF 4a is that, as is clear from FIG. The aperture pulse for each A stage is input from the aperture detection circuit 19 to the counter 4, and distance information for each A stage is output from the decoder 2.
This is because the values for each A stage are compared by the magnitude comparator 6.

For example, if the film sensitivity information is 1SO4, OO, only the left terminal of the switch means 11 is short-circuited by a Pattroy cord (not shown), and only the AND gate 7 among the AND gates 5 to 7 is "H". "L is output, this signal is preset to D-FF4d, and its Q
The output becomes "H" and "L" (However, Iya's D-FF 4a
, 4b, 4c, and 4e are at "low" level (hereinafter abbreviated as 'L''L).

After the film sensitivity information is preset in the counter 4 in this way, the camera sensor control circuit 12
(For example, when there is a change in shooting conditions such as when changing the guide number of a strobe, the correction counter is output so that it moves only when it is necessary to correct the fluctuation, in Figure 1) CK terminal of D-FF13 to “'L”L to l Hl”
Gives the output of L.

At this time, when the D input of the D-FF16 is “H”L, that is,
Preset film sensitivity information D-FF4d Q
The output is “H”L (ISO400 or l5O8
00), the Q output of D-FFi3 becomes "H" and "L". A
The ND gate 14 outputs this signal and the counter 16's "L"
The clock pulse of the oscillator 15 is input to the counter 16 because the inverter gate 17 inverts the output to "HllL".

When the counter 16 counts up to the preset count value for correction, the output of the counter 16 becomes “'H”L.
This is AND through the inverter gate 17.
Since the clock pulses from the oscillator 15 are given as "L" to the gate 14, the counter 16
Do not enter.

The clock pulses input to counter 16 are ORed at the same time.
The counter 4 counts up through the gate 18. Therefore, if you want to increase the contents of counter 4 by two steps, since the count of D-FF4a is at step A,
Since it is sufficient to apply pulses to the CK terminal of the D-FF 4a, the maximum count value set in the counter 16 may be set to 4.

For example, if you want to lower the light intensity of the strobe light by two steps for reasons such as power saving in order to use a film with high film sensitivity as described below, you will need to lower the contents of counter 4 by two steps to compensate for this variation. Must be. At this time, due to the complement relationship, there are 5 stages of counter 4, so 2
By up-counting '-4, that is, 28 clock pulses, it is possible to lower the contents of the counter 4 by two steps.

For example, when the film speed is ISO400, the content of counter 4 is ot ooo, but by up-counting 28 clock pulses, the content becomes o
o too, which is exactly the same as the film sensitivity of ISO 100, which means that the aperture can be increased by two steps, and the contents of counter 4 are lowered by two steps.

This case can be realized by setting the maximum count value set by the counter 16 to 28.

On the other hand, distance information is output from the photographing distance information generating circuit 1, which is converted by the decoder 2 as shown in FIG.

When the release button is pressed to the second stroke,
The shutter blades operate to open, and the aperture detection circuit 19
The aperture pulse is output from. When the first aperture detection circuit 19 outputs the first aperture that detects the opening amount of the shutter blades corresponding to the maximum aperture value 16, that is, D-F.
When the CK terminal of F20 rises from "l L l" L to "H" L, the Q output of D-FF'20 changes to "H" L. Further, the aperture pulse from the aperture detection circuit 19 is input to the counter 4 via the OR gate 18, and is thereby counted up. The contents of the counter 4, which changes from time to time, are given to a magnitude comparator 6 and compared with the comparison information from the decoder 2 described above. When the contents of the counter 4 match or exceed the distance information of the decoder 2, the magnitude comparator 3 outputs “H”.
L is output. At this time, since the AND gate 21 receives this signal as well as the °'H"L signal from the D-FF 20, it outputs 'H"L. This "H" L signal is applied to the strobe trigger circuit 24 via the OR gate 22, which activates the strobe trigger circuit 24 to cause a strobe (not shown) to emit light.

In addition, when all the aperture pulses are output from the aperture detection circuit 19 and the magnitude comparator 6 does not output "H" or "L" even if the aperture is in the open state, the switch is turned on by the second stroke of the release button and the operation starts. The OR gate 2
2 and a strobe trigger circuit 24, the strobe is emitted.

For example, if we give specific numerical values and explain, I S
Using O4QQ film, in order to lower the strobe light output by two steps, the contents of otooo input to the counter 4 are lowered by two steps as described above to 00100, and from the camera to the subject. distance is 2.0
m, the output from decoder 2 is 0110
Therefore, when the shutter blade opens and the aperture value reaches 4.7, that is, after the shutter blade starts operating, the contents of 8 pulses, l1ll, 01.000, enter the counter 4 due to the aperture pulse. , the aforementioned oo
From the information of too, the total count value is 01100
Then, the strobe light emission permission signal (“H” L) coincides with the output of the decoder 2 and is output to the magnitude comparator 6.
It is output from.

Note that it is also possible to use an up/down counter as the counter 4 to count down the correction amount.

Furthermore, the output on the side input to the AND gate l of the switch means 11 may be given as the D input of D −F F'l≦.

Figure $6 is a circuit diagram showing another embodiment of the present invention. 1st
Elements with the same reference numbers as in the figures operate in the same way as in FIG. In the figure, 31 is a pull-down resistor, and 62 is a switch for starting correction for changes in photographing conditions such as focal length conversion, flash light intensity conversion, and exposure correction.One end is connected to the +Vc side of the power supply. , the other end is connected to the pull-down resistor 31 and the p input side of the D-FF 13. 65 is D-
The FF outputs the output from the oscillator 15 to the inverter gate 66.
is input to the CK terminal via the D input side is the power supply +
Input is from the Vc side. 63 is an AND gate which inputs the clock pulse of the oscillator 15 and the summer output of the D-FF 35, and its output is given as an input to the AND gates 5-7. 64 is D −F' F, and oscillator 15
A clock pulse is input to the CK terminal from
The input is the Q output of D-FF35, and its 'Q
It is designed to be given to the CK terminal of the specific output D-FFi3. The other components are the same as those in FIG. 1 and are not shown.

When the release button is pressed to the first stroke, power is applied to this circuit and the initial state is set.

Here, the four outputs of the D-FF 35 are "H"L, and the AND gate 66 which inputs the first clock pulse from the oscillator 15 outputs "H"L, so the film sensitivity information is sent to the counter 4 as described above. is input. At the falling edge of the first clock pulse, that is, at the CK terminal of the D-FF 65, the rising edge of the pulse is input via the inverter gate 66, so at this time, D-FF! ':>35's output becomes "L"L, and the output of AND gate 66 becomes "L".
"L", all the outputs of AND gates 5 to 7 are "L", and the input of film sensitivity information to the counter 4 is terminated.Also, since the Q output of D-FF35 becomes "H"L,
At the rising edge of the second clock pulse from the oscillator 15, the Q output of the D-FF 34 becomes 'H' and L.If the photographer has already turned on the switch 62 to compensate for variations in the photographing conditions. , D input of D-FF16 is 'H''
Therefore, at the time when the Q output of the D-FF 34 rises from "H" to "L", the Q output of the D-FF 13 becomes "I("L. As a result, the count corrected by the counter 16 as described above The number is counted and the calculation of the electric FA is corrected.

The subsequent operations are exactly the same as those described in FIG. 1, and will therefore be omitted. This embodiment has the advantage that correction values based on fluctuations in photographing conditions can be input, regardless of film sensitivity, according to the wishes of the photographer.

FIG. 4 is a circuit diagram of an embodiment of a strobe light whose amount of strobe light emission can be changed. In the figure, 4o is the power supply.
41 is a DC, -DC converter, 42 is a xenon discharge tube, 46 is a first capacitor, 44 is a second capacitor, 45 is a discharge diode, 46 is a thyristor for charge control, 47 is a resistor, 48 is a capacitor, 49
5 is a strobe light emission amount selection device, 50 is a strobe trigger booster circuit, and 51 is a switch. The strobe light emission amount selection device 49 may be configured by inputting a selection signal via an inverter gate (not shown) from the connection point between the resistor 10 shown in FIG. The signal on the output side of 62 may be inputted as a selection signal via an inverter gate (not shown). If the switch 62 is on or the film sensitivity is 15O400 or higher,
Since the level becomes H'''L at this connection point, etc., the strobe light emission amount selection device 49 outputs "L"L to the gate of the thyristor 46 to turn off the thyristor 46.
is off or the film sensitivity is less than ISO 200, the connection point etc. will be "L"L, so the robot light emission amount selection device 49 will set IIH"L to the gate of the thyristor 46.
is output and the thyristor 46 is turned on.

When the battery 40 is connected to the DC-DC converter 41 by turning on the switch 51, a high DC voltage is applied to the strobe trigger booster circuit 50, the xenon tube 42, and the third condenser 9.
-43. When II HII L is output from the strobe light emission amount selection device 49 to the gate of the thyristor 46, the thyristor 46 becomes conductive, and the second capacitor 44 is also charged with the output of the DC-DC converter 41, and the strobe is The amount of light emitted is determined by the first capacitor 46.
and the capacitance of the second capacitor 44. Further, the strobe light emission amount selection device 49 to the thyristor 4
When "L" is output to the gate of 6, the thyristor 46 is in an off state, the second capacitor 44 is not charged, and the amount of strobe light emission is determined by the capacitance of the first capacitor 43. Resistor 47 and capacitor 48 are thyristor 46
This prevents erroneous signals from being input to the gate. By setting the ratio of the capacitances of the first capacitor 43 and the second capacitor 44 to 1:3, the difference between when the thyristor 46 is charged in the on state and when the thyristor 46 is charged in the off state is set to 1:3. The amount of light emitted by the strobe is 1:4, which means that there is a difference of two steps.

The strobe light emission amount selection device 49 turns off the thyristor 46 based on the film sensitivity information when the ISO is 400 or higher, so that even if the light emission amount is two steps smaller than when the ISO is 100, the film sensitivity will be two steps different. By performing correction, the difference in brightness between the subject and the surroundings will be reduced, making it possible to take clear photos while achieving the same effect when shooting, provided the ambient light is the same, and it will also lead to saving energy in the power supply. .

In addition to switching the amount of flash light emitted according to the film sensitivity, it is also possible to switch the amount of light emitted by the strobe independently depending on the conditions.

According to the present invention, it is now possible to add the calculation of conversion of the strobe light emission amount to the calculation of the light emission timing of the electric FA, which has been calculated with the strobe light emission amount being constant.

FIG. 5 is a schematic diagram showing changes in the open aperture value when switching the focus. The focal length on the short focal length side is fl, and the lens 52
If the diameter of the entrance pupil is d, the open F-number is f l/
d, and when the focal length on the long focal length side is f2, the open F-number is f2/d.

If the ratio of both focal lengths is f: f2=l:2, the open F-number will change by a factor of two. In other words, the open aperture value, which is proportional to the open F-number, has changed by two steps. Due to this change in the open aperture value,
The effective aperture value detected by the aperture aperture detection section in the shutter blade will all shift, and to correct this, the amount of shift must be corrected as the variation in aperture value in the above-mentioned calculation of the electric FA. , this can be corrected in the same manner as the above-mentioned correction of the amount of light emitted by the strobe.

For example, when using the standard shooting side as a reference, the telephoto shooting side has 2
Since it is only necessary to perform stepwise correction, switch 62 in FIG.
should be installed on the lens barrel. For example, a section may be provided on the movable lens barrel, and a fixed section may be provided on the outside of the movable lens barrel on the fixed outer station side, so that both sections come into contact with each other in the telephoto shooting state to turn on the switch.

As described above regarding the present invention, in a circuit that implements electric flash auto, correction values for changes in photographing conditions, such as changes in exposure conditions by converting the amount of light emitted by a strobe or converting the focal length of a photographic lens, are used. By making it possible to input corrections corresponding to changes into this circuit, it is now possible to always achieve automatic electric flash under appropriate conditions.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, and FIG. 2 is a circuit diagram of an embodiment of the present invention.
FIG. 6 is a partially omitted circuit diagram of another embodiment of the present invention; FIG. 4 is a circuit diagram of an embodiment of a strobe that can change the amount of light emitted; FIG. The figure is a schematic diagram showing a change in the open F-number due to a change in focal length. 1 is a shooting distance information generating circuit, 2 is a decoder, 6 is a magnitude comparator, 4 is a counter, 11 is a switch means, 12 is a camera sequence control circuit, 16 is a D-
FF, 14.21 is AND gate, 15 is oscillator, 16
is a counter, 17 is an inverter gate, 18.22 is an OR gate, 19 is an aperture detection circuit, 20 is a D-FF, 2
6 is a shutter abort time signal generation circuit, and 24 is a strobe trigger circuit.

Claims (6)

[Claims] (1) An aperture detection circuit that detects the movement of the aperture and outputs it as a digital signal, a film sensitivity information generation circuit that outputs electrical film sensitivity information, and a counter circuit that inputs and counts the outputs of these circuits. , further comprising a decoder circuit that converts and outputs a signal according to the shooting distance. The counter circuit presets the output signal from the film sensitivity information generation circuit, and then counts the output of the aperture detection circuit. In the camera's electric flash auto system, which determines the strobe light emission timing by comparing the count contents and the output of the decoder circuit, a variation correction component outputs a correction value corresponding to fluctuations in the set camera shooting conditions. An electric flash auto system for a camera, characterized in that a pressure circuit is provided, and the counter circuit inputs the output of the pressure circuit for correction of fluctuation after presetting film sensitivity information. (2) The electric flash auto system of the camera according to claim 1, wherein the fluctuation correction partial pressure circuit is interlocked with the film sensitivity information output circuit or the counter circuit at the time of film sensitivity input. (3) A strobe light emission amount conversion means is provided as means for changing the photographing conditions, and the light emission amount conversion means is linked with the film sensitivity information generation circuit. The electric flash auto method of the camera described in . (4) When the counter subtracts from the output of the six recoil compensation output circuits, the fluctuation compensation pressure circuit outputs a pulse that is the complement of the subtracted value, and the counter counts up this pulse. An electric flash auto system of a camera according to claim 1, which performs subtraction. (5) The camera according to claim 1, wherein a strobe light emission amount conversion means is provided as a means for changing the photographing conditions of the camera, and this light emission amount conversion means is linked with the fluctuation correction destination circuit. Electric flash auto method. (6) A means for converting the focal length of the photographing lens is provided as a means for changing the photographing conditions of the camera, and this converting means is linked to a circuit for correcting fluctuations. Flash auto method.