JPS589932B2 - Senkou Hatsu Kokini Okeru Shuu Hasu Sentaku Kugatachi You Kousouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a light control device for stopping flash light emission in accordance with the situation of a photographic scene in a photographic flash light emitting device.

A widely known device of this type is an automatic light control device.
After photoelectrically converting the reflected light from the flash, it is integrated by a capacitor, and when the integrated value reaches a predetermined value, a light emission stop signal is issued.

Therefore, the flash emission time is determined according to the amount of reflected light, so if the distance to the subject is short, the emission time will be short, and conversely, if the distance is long, the emission time will be extended, so the flash emission time will be determined according to the shooting distance. You can get luminescence.

However, this method assumes that the reflectance of the subject is always constant, and if the reflectance varies, the flash firing time will naturally not depend on the photographing distance, making it difficult to fire a flash that provides an appropriate exposure.

Therefore, in the past, the aperture was often adjusted according to the reflectance, but it was extremely difficult to judge the degree of reflection of the subject with the naked eye, and the aperture value was adjusted according to the reflectance of the subject. If you do so, you cannot expect to capture the desired depth of field.

The present invention was developed to solve such problems, and is a flashlight emitter that is capable of emitting a preliminary light emission prior to the main light emission and is equipped with a light emission stop circuit for automatic light control. A pulse oscillator that can be operated to set the number of pulses according to the shooting distance, a light response timer circuit that receives the reflected light from the subject based on the pioneering light emission and determines the output generation time according to this reflected light, and the pioneering light emission. A selection switch that selects the output signal of the photoresponse timer circuit at the time of the main emission, and an output signal sent from the constant signal source at the time of main emission, and the output signal sent through this selection switch are input, and the output signal is present. a gate circuit that opens the gate for a period of time; a frequency divider that divides the frequency of the pulse sent from the pulse oscillator according to the aperture value when the gate of the gate circuit is opened; and a preset counter that counts the pulses after the frequency division;
A preset signal, which is a coincidence signal of the brisset count, is supplied to the light emission stop circuit of the flashlight emitter through a switch member that is closed only when the main light is emitted. a display member for displaying the count value of the brisset counter, and a switch means for inputting a pulse to the frequency divider in synchronization with the operation of the trigger circuit of the flashlight emitter, and causing the first light to emit. The photographing distance is determined from the display on the display member at the time of the shooting, and the number of pulses generated by the pulse oscillator is determined in accordance with this photographing distance to perform main light emission.

FIG. 1 shows an example of the basic circuit of this invention, 01,0,...
03...On are pulse oscillators with different oscillation frequencies, and these oscillators are designed to oscillate at frequencies corresponding to each of the photographing distances set in advance in several stages.

For example, oscillator 0 has a frequency f corresponding to an imaging distance of 1 m.
1, the oscillator 02 has a frequency f2 corresponding to a distance of 2 m,
The oscillators 03 each oscillate at a frequency f3 corresponding to a distance of 3 m.

Switches S1, S2, S3...S arranged for each oscillator
n is for selecting one of the oscillators according to the visually measured photographing distance.

Each oscillator output is an and circuit a1, a2, a3...an
, frequency divider 3 via OR circuit 1 and trigger switch 2
supplied to

Also, the output of the OR circuit 1 is the trigger circuit 4 of the flashlight emitter 4.
supplied to a.

A low-return switch 5 is provided on the output side of the frequency divider 3, and the switch 5 is configured to be switched in accordance with the aperture control value of the camera.

Reference numeral 6 denotes a brisset counter that counts pulse signals supplied via the rotary switch 5.

A rotary switch 7 is provided on the output side of the counter 6 so that a preset value of the counter can be selected.

The match signal of the preset counter 6 is sent to the low reset switch 7.
The light is supplied to the light emission stop circuit 4b of the flashlight emitter 4 via.

In this basic circuit example, each oscillator is caused to oscillate prior to starting flash light emission, and in this state, one of the oscillators is selected.

For example, if the subject is 1m in front of the camera,
This photographing distance is determined on the eye side, and the oscillator 01 corresponding to this photographing distance is selected.

Selection of oscillator 01 is effected by closing switch S, as described above.

Next, when the camera shutter is opened, the trigger switch 2 is closed in synchronization with this, and a pulse signal from the oscillator q is supplied to the frequency divider 3 and the trigger circuit 4a.

The trigger circuit 4a is activated by the first pulse of the supplied pulse signal to start flashlight emission.

On the other hand, the pulse signal is converted by the frequency divider 3 into a frequency according to the diaphragm control value, and then supplied to the preset counter 6.

When the preset counter 6 counts up to the preset value (for example, the position of the counting element 6c), the rotary switch 7
A match signal is generated through the light emitting device 4, and this match signal operates the light emission stop circuit 4b to stop light emission.

Since the amount of flash light emission is determined by the time it takes for the preset counter 6 to count up to the preset value, it depends on the oscillation frequency f1 of the oscillator 01.

Next, when it is determined that the visually measured shooting distance is 2 m, the switch S2 is closed and the oscillator 02 is selected.

In this case as well, the flash light emission is started and stopped in the same manner as described above, but since the oscillation frequency f2 of the oscillator 02 is lower than the oscillation frequency f1 of the oscillator 01, the counter time of the preset counter 6 becomes correspondingly longer.

Therefore, the amount of flash light emission increases, and the amount of light emission corresponds to the shooting distance of 2 m.

The same applies when the shooting distance is extended to 3 m, 4 m, and 5 m, and the frequency of each oscillator is f3>f,>
The amount of flash light emission is determined according to f,...>fn, and the amount of light emission corresponding to each shooting distance can be obtained.

In addition, when adjusting the counter time to the preset value of the preset counter 6 to be equal to the appropriate light emission time, the switching position of the low reset switch 7 is determined experimentally.

After the appropriate point of this switch 7 is determined experimentally, the film sensitivity can be set by switching the switch 7.

Further, the light emission stop circuit 4b of the flashlight emitter 4 described above may be of a bypass type in which a switch member is connected in parallel to the light emitting tube or a current cutoff type in which a switch member is connected in series to the light emitting tube. It is also possible to arrange a chemical substance (kerrcell) exhibiting a light-shielding property on the front surface of the arc tube.

FIG. 2 shows a case where one pulse oscillator is used in the basic circuit example described above, and the frequency of the oscillator 8 can be adjusted by operating the pointer 8b of the variable resistor 8a according to the distance scale 9.
〉f2〉f3...>f changes as follows.

Therefore, similarly to the basic circuit example described above, it is possible to obtain the amount of flash light emitted with respect to the photographing distance.

FIG. 3 shows an embodiment of the present invention in which a photographing distance display device is added to the basic circuit example shown in FIG. 1.

That is, in the basic circuit example shown in Figure 1, the photographing distance is determined by visual measurement and the pulse oscillator corresponding to the photographing distance is selected, but in Figure 3, an indicator lamp is provided to indicate the photographing distance, and the main flash is activated. Prior to this, the flash light emitting tube is caused to emit light first, and the reflected light is used to light up the indicator lamp, thereby obtaining an accurate photographing distance.

If the photographing distance can be determined from the lighting of the indicator lamp, it is possible to select a pulse oscillator corresponding to that distance and perform the main light emission in the same manner as in the previous embodiment.

In the embodiment of FIG. 3, the same instruments and members as those shown in FIG. 1 will be described with the same reference numerals.

First, the output of the photoresponse timer circuit 10 is given to the input of the AND circuit a1+a2... placed on the output side of the pulse oscillators 01, 02...
The gate opening times of the d circuits al, a2, . . . are configured to correspond to the photographing distance.

Here, the photo-responsive timer circuit 10 includes a photo-sensing element P and a resistor R.
It is composed of a series circuit with , and a Schmitt circuit (transistors T1 and T2) that determines the inversion time depending on the potential of the connection point M of this series circuit.

11 is a changeover switch, 11a is a terminal for pioneer emission, 11b is a terminal of the present invention, and 11n is a terminal for play.

The operation of the timer in this configuration will be explained below with reference to the characteristic curve shown in FIG.

Considering the potential of the connection point M between the photo-sensing element P and the resistor R, if the subject is located at a short distance at the time of the pioneering light emission, the potential will be the highest as shown by curve A in Figure 4; When the subject is located further away than the distance, the potential decreases sequentially as shown by curves B and C.

Therefore, the switching level of the Schmitt circuit is shown in Figure 4 (■).

By setting the time t1 at the A curve potential and B
The Schmitt circuit performs an inversion operation corresponding to time t2 when the potential is on the curve, and time t3 when the potential is on the C curve.

However, when the shooting distance is 1 m, the A curve is
If we assume that curve B occurs when the distance is 3 m, and curve C occurs when the distance is 3 m, each an
A timer signal is supplied to the d circuits a1, a2, . . .

Next, pulse signal AND circuits a1' and a2' of each oscillator
... is supplied to the trigger circuit 4a of the flashlight emitter 4 via the OR circuit 1', and the trigger switch 2 is provided with an operation switch 2' for the first light emission.

On the other hand, during the pioneering flash, the low-return switch 5, which follows the aperture control value, is connected to a predetermined terminal position, for example, the terminal 5a, so that a constant frequency conversion is always performed during the pioneering flash. Configure.

In addition, an idle terminal 7n is provided in the low resetting switch 7 disposed on the output side of the brisset counter 6, and by closing the switch 7 to the terminal In at the time of the first light emission, the circuit of the coincidence signal (light emission stop signal) is opened. let

Lamps L1, L2, L3, . . . connected to the output side of each counting element of the preset counter 6 are display lamps that indicate the shooting distance. When the display lamp L1 is lit, the distance is Im, and when the display lamp L2 is lit, the distance is Im. The lighting position of the indicator lamp is predetermined to indicate the photographing distance, such as 2 m.

It should be noted that it is easy to understand that each display lamp may be connected to the counter 6 via a decoder.

In this embodiment constructed as described above, first, prior to photographing, the rotary switch 5 is turned on to the terminal 5a, the rotary switch 7 is turned on to the terminal 7n, and the changeover switch 11 of the optical response timer circuit 10 is turned on to the terminal 11a. Insert it and prepare for the pioneer light emission.

Next, a pulse oscillator is selected according to the visually measured photographing distance, but in this case, it is not necessary to know the exact photographing distance.

For example, if it is determined by visual measurement that the photographing distance is 1 m, switch S1 is turned on to select oscillator 01.

However, it is assumed that each oscillator is in an oscillating state in advance.

Then, when the operation switch 2' is turned on, the oscillator 01
The pulse signal is transmitted to the circuit 4a via the AND circuit a1' and the OR circuit 1', and the flash tube starts emitting light almost simultaneously with the operation switch 2' being turned on.

Since the light sensing element receives light due to the start of light emission, a potential as shown by the curve in FIG. 4 appears at the connection point M.

For example, if the subject is located exactly 1 m in front of the camera, the curve will be like A curve, and the gate of the AND circuit a1 will be open for a time t1.

Therefore, during time t1, a pulse signal from the oscillator O1 is supplied to the preset counter 6 via the OR circuit 1, the frequency divider 3, and the rotary switch 5.

In this case, the oscillation frequency of pulse oscillator 01 is the highest,
In addition, since the gate open time of the AND circuit a1 is long as shown by t1, the count number of the preset counter 6 increases, and the indicator lamp L1 lights up.

If the display lamp L1 lights up, the user can know that the shooting distance is correctly 1 m.

However, if we consider a case where the photographing distance is 2 m, but it is visually estimated to be 1 m, and the switch S1 is turned on to select the pulse oscillator O1, the connection M of the photoresponse timer circuit 10 is connected as shown in Fig. 4. Since a dropped potential appears as shown in the upper curve B, the gate opening time of the AND circuit a1 becomes t2.

Therefore, since the pulse signal of the oscillator 01 is supplied to the preset counter 6 during the time t2, the indicator lamps L and 7 do not light up, and at least one of the indicator lamps located to the left of the indicator lamp L, 7 lights up. The indicator lamp will light up.

Since it can be determined that the photographing distance is 1 m or more, the distance confirmation operation is performed again.

That is, by turning on the switch S2, selecting the oscillator 02, and operating it in the same manner as described above, the pulse signal of the oscillator 02 can be supplied to the preset counter 6 during the time t2, and at this time the indicator lamp L2 lights up. Therefore, we know that the shooting distance is correctly 2 m.

In this way, the shooting distance is confirmed,
If the shooting distance is close, such as 1m or 2m, there will be no major misidentification by visual measurement, but if the shooting distance is long, such as 5m to 7m, the error caused by visual measurement becomes large, and this may occur. This embodiment is more effective in such cases.

After correctly knowing the shooting distance from the above, select the pulse oscillator corresponding to that distance, and then connect the selector switch 11 of the photoresponse timer circuit 10 to the terminal 1lb and set the low reswitches 5 and 7 to the old one. It will continue to operate until it is restored to the original position.

Thereafter, by moving the camera shutter to open and closing the trigger switch 2, it is possible to obtain the amount of flash light emitted according to the photographing distance, similarly to the basic circuit example in FIG.

In the above description, the pulse oscillator is selected according to the photographing distance measured visually at the time of the pioneering light emission, but it is also possible to specify a certain pulse oscillator and use this oscillator to confirm the distance.

For example, if only pulse oscillator 01 is selected, a pulse signal of a constant frequency is applied to the gate open time of AND circuit a1 (
(distance to the subject) t1, 12, 13, . . . are supplied to the preset counter 6, so the lighting position of the display lamp is determined in accordance with the times t1, t2, t3, .

Therefore, the photographing distance can be known from the lighting position of this indicator lamp.

In addition, for checking the shooting distance, a pulse oscillator is set to oscillator 0.
1, 02, etc. may be newly provided.

FIG. 5 shows the pulse oscillator 01 in the embodiment shown in FIG.
02, .

Although the embodiments of the present invention have been described above, the rotary switch 5 shown in FIGS. 1 and 3 may be operated separately according to the camera aperture control value.
A drive circuit 16 may be provided to drive the rotary switch 5, and this circuit may be linked to the rotary switch 5.

As described above, in the present invention, a pulse signal whose frequency corresponds to the shooting distance is supplied to the brisset counter, and a coincidence signal from the counter is transmitted to the light emission stop mechanism to stop the light emission, so that the light emission is stopped when the shooting distance changes. In some cases, the frequency of the pulse signal may be converted according to the distance,
Therefore, the camera aperture can be held constant regardless of changes in the photographing distance, and photography can be performed with the intended aperture control value, allowing for sufficient consideration of the depth of field.

Furthermore, the present invention can be implemented using a digital circuit, which means that the influence of ambient temperature or power supply voltage fluctuations on the device is small, and there is no need for integrating means using capacitors as in conventional devices. Since there is no leakage current error due to this capacitor, it can be highly evaluated in terms of accuracy.

Furthermore, in this invention, the amount of flash light emission corresponding to the shooting distance is determined experimentally in order to obtain appropriate exposure, so once the shooting distance is determined, the frequency of the pulse signal can be easily selected, which is extremely convenient in operation. .

On the other hand, as shown in the embodiment shown in Figure 3 above, if the photographing distance is confirmed in advance by the pioneer flash before the main flash is performed, the accurate frequency of the pulse signal can be selected, and even when the photographing distance is long. Even when the distance to the subject cannot be clearly determined due to dim light, accurate light control operation can be obtained and there is no risk of failure in photographing.

[Brief explanation of drawings]

FIG. 1 is a program diagram showing an example of a basic circuit of a light control device according to the present invention, FIG. 2 is a program diagram showing a modified configuration of a pulse oscillator provided in the basic circuit example of FIG.
FIG. 3 is a program diagram showing an embodiment of the light control device according to the present invention, FIG. 4 is a diagram showing a characteristic curve of the photoresponse timer circuit provided in the embodiment of FIG. 3, and FIG. This is a block diagram of a modified example pulse oscillator configuration. 0,02,03...On...Pulse oscillator,
2...Trigger switch, 2'...Operation switch, 3...Divider, 4...Flashlight emitter, 4a... Trigger circuit, 4b...
・Emission stop circuit, 5...Rotary switch, 6
...Breset counter, 7...Rotary switch, 8...Pulse oscillator, 9...
...Distance scale, 10...Light response timer circuit, L1, L2, L3...L6...Display lamp, 12...Pulse oscillator, 14... Distance scale, 15...Aperture device, 16...Aperture drive circuit.

Claims (1)

[Claims] 1. A flashlight emitting device that can emit a pioneering flash prior to the main flash and is equipped with a flash stop circuit for automatic flash control, and a pulse oscillator that can be operated to set the number of pulses according to the shooting distance. , a light response timer circuit that receives the reflected light from the subject based on the pioneer light emission and determines the output generation time according to this reflected light; a selection switch that selects each output signal from the source; a gate circuit that receives the output signal sent through the selection switch and opens the gate while the output signal is present; a frequency divider that divides the frequency of the pulses sent from the pulse oscillator according to the aperture value; and a preset counter that counts the pulses after the frequency division;
a circuit that supplies a preset signal, which is a coincidence signal of the preset counter, to a light emission stop circuit of the flashlight emitter via a switch member that is closed only when the main light is emitted; a display member that displays the count value of the preset counter; A switch means is provided for inputting pulses to the frequency divider in synchronization with the operation of the trigger circuit of the flashlight emitter. A frequency selective light control device which performs main light emission by determining the number of pulses generated by the pulse oscillator according to the distance.