JPS5840731B2 - Senkouhouden Hatsukoukiniokel Hatsukoseigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flash discharge light emitting device used for photography, and particularly proposes a new light emission control device for forcibly stopping flash discharge light emission.

This type of light emission control device is of the parallel type, which controls the ON control of a switching member connected in parallel to the discharge arc tube to stop the light emission, and the other is a parallel type, which measures the ON control of a switching member connected in parallel to the discharge arc tube, and controls the OFF'F of a switching member connected in series to the discharge arc tube to stop the light emission. The switching member can be roughly divided into a serial type and a serial type, but in both types, the switching member is controlled by an analog control circuit.

For example, an integrating circuit is provided in which a light-receiving element that receives reflected light from a subject and a capacitor are connected in series, and an output signal is generated when the integrated value of this circuit reaches a predetermined value. In many cases, the switching member is turned ON (or OFF) by this output signal.

By the way, with this kind of analog control, fluctuations in power supply voltage,
Since it is easily affected by changes in ambient temperature, and the integration time of the integration circuit is on the order of tens of microseconds,
The output signal (integral signal) appearing as the capacitor terminal voltage becomes extremely unstable.

Conventionally, it has been difficult to achieve highly accurate dimming control for these reasons.

Therefore, in the present invention, the switching member connected in parallel or series to the discharge luminous tube is controlled to be turned on or off using a control circuit constituted by a pulse circuit, thereby solving the above-mentioned defect.

Therefore, the present invention includes a conversion circuit that converts the intensity of reflected light from a subject based on flash discharge light emission into a voltage, and a plurality of switching members whose switching levels are determined in stages, and each switching member has a conversion circuit that converts the intensity of reflected light from a subject based on flash discharge light emission into a voltage. It includes a selection circuit that performs selection operation by inputting a voltage signal, and a plurality of pulse oscillators provided to increase the oscillation frequency in stages. A selected pulse oscillator circuit, a counting circuit that counts the oscillation pulses of the selected pulse oscillator, and a light emission stop circuit that operates by inputting a counting signal generated when this counting circuit counts up to a predetermined count value. A light emission control device for a flash discharge light emitting device is proposed.

The embodiments shown in the drawings will be explained below.

In FIG. 1, block A indicated by a dotted line is a pulse oscillator circuit, which includes pulse oscillators L2, 3, and 4.

The frequencies of the oscillators L2, 3, and 4 are determined in stages,
If the frequency of oscillator 1 is fl, oscillator 2 is f2, oscillator 3 is f3, and oscillator 4 is f4, fl<f2<f3.
<f.

Inhibition gate circuit la connected to these oscillators.

2a, 3a and an AND circuit 4a are gate circuits for oscillating pulses, and the gates are sequentially opened by a selection circuit to be described later.

The oscillation pulse of each oscillator is passed through an OR circuit 5 to a counting circuit 6.
and is counted up to a predetermined count value here.

The count value scheduled here is set by the rotary switch 7.

The counting circuit 6 is connected to the display lamps L1 through the decoder 8.
L'to is connected, and the lamp position to be lit is determined according to the number of pulses actually counted.

When the counting circuit 6 has counted up to a predetermined count value, a counting signal is generated via the rotary switch 7, and this signal is transmitted to the light emission stop circuit of the flash discharge light emitting circuit B.

As shown in the figure, the flash discharge light emitting circuit B has a known circuit configuration and includes a light emitting stop circuit consisting of a commutating capacitor 9 and an SCR element 10.

Then, since the count signal is transmitted to the gate of the SCR element 10, the SCR element 10 is turned on.

Therefore, the SCR element 1 connected in series to the discharge luminous tube 11
Since a reverse current flows through the commutator capacitor 2, the SCR element 12 stops emitting OF''FL light.

The flash discharge light emitting circuit B includes a trigger circuit 13, a tuning switch 14, and a step-up transformer 15.

Next, block C indicated by a dotted line is a conversion circuit that converts the reflected light from the subject into an electrical signal for flash discharge light emission.A resistor 17 is connected in series to a light receiving element 16 such as a phototransistor, and this connection point a The base of a transistor 18 for amplification operation is connected to the base of the transistor 18 for amplification operation.

Since a voltage similar to the flash discharge light emission curve appears at the connection point a as shown by curve I in FIG. 2, an output voltage shown by curve 2 in FIG. 2 appears at the output section of the circuit C.

On the other hand, block D indicated by a dotted line in FIG.
It is composed of 9, 20, and 21.

These transistors have their bases in common and are connected to the output section of the conversion circuit C, and their emitter voltages are el, e2 . e3. Add e4.

This emitter voltage has a relationship of el>e2>e3>e4, so that each transistor 18, 19, 20,
21 switching level v18.21 in FIG. v10.
Set V2o, V2□.

In this embodiment configured as described above, each oscillator 1, 2, 3, and 4 is started to oscillate in advance by turning on the power switch.

Thereafter, the tuning switch 14 is closed in conjunction with the opening of the camera shutter, and the discharge luminous tube 11 is closed by a known means.
0 emission start is performed.

Since the subject E reflects flash discharge light emission onto the light receiving element 16 of the conversion circuit C, the intensity of the reflected light received by the light receiving element 16 changes depending on the distance from the subject E.

Therefore, assuming that the subject E is at a relatively short distance, a converted voltage like the I curve in FIG. 2 appears at the connection point a of the conversion circuit C, so that the An output voltage is generated that follows the ■ curve in Figure 2.

Note that this output voltage is a high voltage unless flash discharge light emission occurs, so each transistor of the selection circuit that receives this output voltage as a base is turned on.

However, as the flash discharge progresses, the voltage at the output section drops, and at time t1 in FIG. 2, the transistor 18 in the selection circuit turns off from on. Since the collector voltage rises rapidly, this voltage is supplied to the prohibition gate circuit 1a, so that only the prohibition gate circuit 1a opens its gate.

That is, the first power of the inhibit gate circuit 1a receives the collector voltage of the transistor 18, the second power receives the oscillation pulse of the oscillator 1, and the third power receives the collector voltage of the transistor 18.
In order to receive the collector voltage of No. 9 (zero at this point) in an inverted state, the gate of the inhibition gate circuit 1a is opened.

Therefore, the oscillation pulse (frequency f1) of the oscillator 1 is supplied to the counting circuit 6.

Incidentally, at this point, the first input power of the inhibition gate circuits 2a, 3a and the AND circuit 4a is 19.20 mm for each transistor.
, 210 receives the collector voltage (zero voltage), so the gates are in a closed state, and the oscillation pulses of the oscillators 2, 3 and 4 are cut off.

Next, when time t2 in FIG. 2 is reached, the transistor 19 in the selection circuit changes from ON to OFF, and the prohibition gate circuit 2a opens its gate, but the collector voltage of this transistor 19 is inverted and at the same time the prohibition gate circuit 1a
Since the signal is input to the circuit 1a, the gate of the circuit 1a is closed.

Thus, only the oscillation pulse (frequency f2) of the oscillator 2 is supplied to the counting circuit 6.

Subsequently, when time t3 in FIG. 2 is reached, the transistor 20 in the selection circuit changes from ON to OFF, so that the gate of the inhibition gate circuit 3a opens and at the same time the gate of the inhibition gate circuit 2a closes.

Therefore, the oscillation pulse (frequency f3) of the oscillator 3 is supplied to the counting circuit 6.

Here, the counting circuit 6 receives the frequency f1. f2. This means that the pulses of frequency f3 are counted sequentially, and while counting the pulses of frequency f3, the predetermined count value is reached and the rotary switch 1 generates a count signal.

As described above, this count signal is transmitted to the light emission stop circuit of the flash discharge light emitting circuit B to stop the discharge light emission.

Furthermore, the discharge light emission stops while the counting circuit 6 receives the oscillation pulse from the oscillator 3, but the amount of discharge light emission that has occurred up to that point is determined experimentally so that it is the appropriate light amount for the subject. .

Next, assuming that the subject E is located far away,
Since the reflected light from the subject becomes weaker than before due to flash discharge light emission, a voltage shown by the curve I' in FIG. 3 appears at the connection point a of the conversion circuit C.

Therefore, the output voltage of conversion circuit C becomes the curve ■' in the same figure,
Only the transistor 18 in the selection circuit is turned off.

Therefore, the oscillation pulse (frequency f1) of the oscillator 1 is supplied to the counting circuit 6, and the circuit 6 reaches a predetermined count value while counting the pulses and generates a count signal.

However, in this case, pulses with a low frequency f1 are counted up to the planned count value, so the counting time becomes longer.

In other words, the light emission time becomes longer.

In comparison, in the above case, the counting circuit 6 has a frequency f1
．． f2. Since the pulses of f3 were counted, the counting time becomes faster at an accelerated rate, and the light emission time becomes shorter.

(Frequencies f, , f2. f3 are fl as mentioned above)
The relationship is <f2<f3, and it increases step by step.

) Furthermore, if the subject is so far away that the flash discharge light does not reach sufficiently, the transistor in the selection circuit cannot be turned off by the output voltage of the conversion circuit C, and no pulse is supplied to the counting circuit 6. .

Therefore, the indicator lamps L1 to LIO connected to the counting circuit 6
Since it does not light up, I know that I cannot take a picture with the appropriate amount of light.

In this case, the camera will move a little closer to the subject E and perform synchronized photography.

FIG. 4 shows another embodiment of the present invention, in which the conversion circuit C and selection circuit of the embodiment shown in FIG. 1 are modified.

Therefore, circuits and members that are the same as those shown in FIG. 1 are given the same reference numerals.

The feature of this embodiment is that each resistor 25°26.2γ having a stepwise different resistance value is connected in series to the light receiving elements 22, 23, and 24 arranged at the same distance from the subject E.
These connection parts o, p.

The oscillators 1, 2, and 3 are sequentially selected based on the voltage appearing at Q.

Therefore, the relationship between the resistance value R1 of the resistor 25, the resistance value R2 of the resistor 26, and the resistance value R3 of the resistor 27 is expressed as R1>R2>
It is defined as R3.

When the light receiving elements 22, 23, and 24 are simultaneously irradiated with the reflected light from the object before the flash discharge is emitted, a voltage Vo is generated at the connection O, opening the gate of the inhibiting gate circuit 1a, and starting the oscillator. 1 oscillation pulse is supplied to the counting circuit 6.

Subsequently, when the voltage at the connection point P reaches VP, the gate of the prohibition gate circuit 2a is opened, and at the same time, the gate of the prohibition gate circuit 1a is closed, and the oscillation pulse of the oscillator 2 is transmitted to the counting circuit 6.
supply to.

If the reflected light from the subject is strong, the voltage at connection Q will continue to be ■
, so the gate of the inhibition gate circuit 3a is opened,
At the same time, the gate of the inhibition gate circuit 2a is closed, so that the oscillation pulse of the oscillator 3 is supplied to the counting circuit 6.

However, each voltage at the connection parts O2P and Q is vo-vP=vQ
, and the sono value is the inhibition gate circuit 1a, 2a
, 3a is at a sufficient level voltage to open the gates.

In this embodiment as well, if the subject E is far away, the oscillator 1
is selected, and if it is close, oscillators 1 and 2 are selected.
, 3 are selected in sequence, and the counting time of the counting circuit 6 is determined by the oscillation pulse of the selected oscillator, so that the flash discharge light emission can be automatically adjusted in accordance with the distance to the subject as in the previous embodiment.

FIG. 5 shows an example in which the present invention is applied to an internal light receiving type flash discharge light emitting device, and the same circuits and members as those shown in FIG. 1 will be described with the same reference numerals.

In this application example, in addition to the main light emitted by the flash discharge light emitting circuit B, a preliminary light emitting circuit F is provided to emit light prior to the shutter release of the camera.

Further, the light receiving element included in the conversion circuit C is arranged, for example, in a camera finder and configured to receive preliminary light emission transmitted through a photographing lens.

Furthermore, the oscillation pulses from the oscillator circuit section A are supplied to a known addition and counting circuit 6 via a gate circuit G which opens the gate according to a set time of a timer circuit T.

The counting circuit 6 functions as a memory circuit only in this application example.

H is a constant frequency pulse oscillator, and this oscillation pulse is supplied to a known subtraction counting circuit 28 via a switch S that is turned on in synchronization with the start of main light emission.

Reference numeral 29 denotes a known matching circuit that compares the counted values of the counting circuits 6 and 280 and generates a matching signal when the counted values become equal.

In such an application example, the intensity of the light reflected from the object is detected by the preliminary light emitted prior to the shutter release of the camera.

That is, the output voltage of the conversion circuit C is determined according to the reflected light from the subject as soon as the preliminary light emission is started, and this output voltage is used to sequentially select the oscillators included in the pulse oscillator circuit via the selection circuit as in the embodiment shown in FIG. do.

The oscillation pass /L/ by the pulse oscillator circuit is generated by the counting circuit 6 during the gate opening time determined by the timer circuit T.
supplied to

The counting circuit 6 counts and stores the supplied pulses.

The counting circuit 6 stores a large number of pulses when the subject is close to the subject, and the memory capacity decreases as the subject is far away.

On the other hand, when the shutter release is performed in this memorized state, the switch S is closed at the same time as the main light emission occurs, and a constant frequency pulse is supplied to the counting circuit 28.

Therefore, when the count value of the counting circuit 28 becomes equal to the storage capacity of the counting circuit 6, a coincidence signal is generated from the coincidence circuit 29, and this coincidence signal is transmitted to the light emission stop circuit of the flash discharge light emission circuit B. This allows natural light control for the required shooting distance.

Further, in this application example, the same effect can be obtained by using the counting circuit 6 as a subtraction type and the counting circuit 28 as an addition type.

As described above, in this invention, a plurality of pulse oscillators whose frequencies are determined in stages are provided, and these oscillators are sequentially selected according to the intensity of reflected light from the subject, and the oscillation pulses of the selected oscillators are set in advance. By counting up to a predetermined count value, a count signal for stopping the light emission is obtained, so it is possible to digitize the light emission control circuit for measuring the stop of light emission. It is possible to obtain an accurate amount of light emitted according to the subject distance by reducing the influence of changes in Since the frequency can also be high, a highly accurate light emission control device can be proposed.

Furthermore, the capacitor in the conventional integration circuit was not able to obtain an accurate light emission stop signal due to leakage, but this problem has been solved by the present invention, so it is possible to perform the light emission control necessary to always give the appropriate exposure. It can be done.

Furthermore, in the present invention, it is easy to take into account photographic conditions such as film sensitivity or aperture.

- That is, this can be easily done by varying the rotary switch 1 of the embodiment shown in FIG. 1 or by inserting a frequency dividing circuit between the pulse oscillator circuit and the counting circuit 6 and adjusting this .

In the above embodiment, the light emission stop circuit of the flash discharge light emitter/path B is shown as a series type, but it can also be satisfactorily implemented in a parallel type in which a switching member such as an SCR element is provided in parallel to the discharge luminous tube 11. In addition, as this light emission stopping circuit, a physical substance (kerreel) that exhibits a light-shielding property according to a change in applied voltage may be arranged in front of the discharge luminous tube 11.

Furthermore, although four pulse oscillators are used in the embodiment shown in FIG. 1 and three pulse oscillators are used in the embodiment shown in FIG. 4, the number of pulse oscillators may be changed as necessary. All you have to do is decide.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a light emission control device embodying the present invention;
3 and 3 are operating characteristic diagrams showing the output voltage of the conversion circuit used in the above embodiment, FIG. 4 is a circuit diagram showing another embodiment of the present invention, and FIG. 5 is a diagram showing an application example of the present invention. It is a circuit diagram. A: Pulse oscillator circuit, B: Flash discharge light emitting circuit, C: Conversion circuit, D:
・Selection circuit, E...Subject, L2, 3, 4...
...Pulse oscillator, 6...Counting circuit, 7.
...Rotary switch, 16°22.23,2
4... Light receiving element, F... Preliminary light emitter,
G...Gate circuit, T...Timer circuit, H...Constant frequency pulse oscillator, 28...
・Counting circuit.

Claims (1)

[Claims] 1 Contains a conversion circuit that converts the intensity of reflected light from a subject based on flash discharge light emission into a voltage, and a plurality of switching members whose switching levels are determined in stages, each switching member inputting the voltage signal of the conversion circuit. A pulse oscillator circuit that includes a selection circuit that selectively operates and a plurality of pulse oscillators provided to increase the oscillation frequency stepwise, and each pulse oscillator is selected by the selection circuit according to the intensity of reflected light from an object. , a counting circuit that counts the oscillation pulses of the selected pulse oscillator, and a light emission stop circuit that operates by inputting the counting signal generated when this counting circuit counts up to a predetermined count value. Light emission control device for the vessel.