JPH01172822A - Variable light quantity type flash light emission device - Google Patents

Abstract

PURPOSE:To correct excessive light emission by allowing an integrator to integrate the photoelectric conversion signal of flash light emission by addition to a correction signal, and advancing the output generation time point of a comparator corresponding to the correction signal. CONSTITUTION:The correction signal S5 made to correspond to the excess of the quantity of flash light emission generated corresponding to the set value of a reference signal S7 is charged previously in an integrating capacitor 32 and then the photoelectric conversion signal of flash light emission by a phototransistor 33 is then charged in the integrating capacitor 32. Therefore, the generation point of the output of a comparator 30 sent out when the integral signal S6 reaches the reference signal S7 is advanced corresponding to the correction signal S5. Consequently, the excessive light emission can be corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a so-called manual type flash light emitting device in which the amount of light emitted by flash light can be changed according to operational settings.

``Prior Art'' A flash light emitting device that can determine the amount of light emitted according to operational settings has been widely known, and a circuit diagram showing an example of the conventional example is shown in FIG.

In this circuit diagram, 11 is a battery power source, 12 is a power switch, 13 is a converter, and 14 is a rectifying diode, and these members 11 to 14 form a power supply circuit consisting of a DC-DC converter.

A main discharge capacitor 15 stores electrical energy, and is charged to a predetermined voltage by the oscillation of the power supply circuit.

16 is a flash discharge tube that discharges the energy stored in the main discharge capacitor 15 and converts it into light energy.

17 is a trigger capacitor, 18 is a trigger transformer,
19 is 5CR12 as a trigger switching element
0 is a starting signal terminal, and these members 17 to 20 form a trigger circuit that applies a high voltage pulse to the excitation electrode 21 of the flash discharge tube 16 to start light emission.

That is, when a starting signal is applied to the starting signal terminal 2o from the camera side, 5CR19 is transferred to a conductive state, and the charge of the trigger capacitor 17 is transferred to the trigger transformer 1.
Because it flows to the primary coil of 8.

The high voltage pulse induced in the secondary coil causes the excitation electrode 21
is applied to

As a result, the flash discharge tube 16, which has become low in impedance, discharges the charge in the main discharge capacitor 15 and starts emitting flash light.

22 is a commutating capacitor, and a series circuit of resistors 23, 24 and capacitor 25 forms an impedance circuit.
When the flash discharge tube 16 starts discharging, its initial current flows through the commutating capacitor 22 to the impedance circuit, and the 5CR 26 receives the voltage change of the impedance circuit at its gate and becomes conductive.

27 is an SCR as a switching element, and this 5CR
27 and the commutating capacitor 22 form a light emission stop circuit.

The commutating capacitor 22 is charged in advance to the polarity shown in the figure via the resistors 28 and 29, and this charging voltage is applied as a reverse voltage between the anode and cathode of the 5CR26 due to conduction of the 5CR27, and the capacitor 2 of the impedance circuit is
5 is discharged through the 5CR 27 and a reverse gate voltage is applied, so the 5CR 26 becomes non-conductive and the flash discharge tube 16 stops emitting flash light.

On the other hand, 30 is a comparator, 31 is the corresponding comparator 3
32 is an integrating capacitor; 33 is a phototransistor that directly receives flash light from the flash discharge tube 16 and converts it into electricity; 3
4, 35, 36 are transistors, and 37 is a start signal terminal, which forms a photoresponse circuit.

A starting signal is input to the terminal 37 of this photoelectric response circuit together with the above-mentioned trigger starting signal terminal 2o, and the transistor 36 is turned ON, the subsequent transistor 34 is turned ON, and the transistor 35 is turned OFF.

From this, the phototransistor 33 enters the power supply state,
Upon receiving the flash light, a photoelectric conversion current flows into the integrating capacitor 32 and is integrated.

When the integral value of the integrating capacitor 32 reaches a predetermined value, the output of the comparator 30 becomes High voltage, and the transistor 38 is turned on.

As a result, the transistor 39 temporarily becomes ONL, 5C
Since R27 receives the gate voltage and becomes conductive, the flash light emission is stopped by the operation of the light emission stop circuit described above.

As mentioned above, this type of flash light emitting device has a variable resistance of 3
1, and by changing the reference signal value, the output generation point of the comparator 30 is changed to obtain a desired amount of flash light emission.

Note that the illustrated reference numeral 40 is a current limiting coil, and 41 is a back electromotive force absorption diode.

"The problem that the invention attempts to solve" The above flash light emitting device has the following problems.

From the point in time when the light emission amount control circuit consisting of a light response circuit, a light emission stop circuit, etc. stops, the flash continues to emit light for a short time, and then the light emission stops. The reason for this is that when the 5CR 26 connected in series to the flash discharge tube 16 becomes non-conductive, the discharge current of the flash discharge tube 16 is transferred to the commutating capacitor 22.
．． This is because the current continues to flow through the path of 5CR27 and charges the commutating capacitor 22 so that the polarity is opposite to that shown. The flash light emission caused by such an operation continues until the commutating capacitor 22 reaches a predetermined charging voltage due to the discharge current of the flash discharge tube 16, and this becomes surplus light emission.

Note that since the resistor 28 has a high resistance that allows a current to flow below the conduction maintenance current of 5CR27, the discharge current flowing through the commutating capacitor 22 is reduced, so that the 5CR2
7 becomes non-conductive.

Figures 5 (a), (b), and (Q) show the flash light emission states when the operating setting value of the reference signal is changed in three stages, and the excess light emission Q is shown as indicated by diagonal lines. be exposed. Note that Tx is the time point at which the output of the comparator 3o is generated.

Excess light emission appears most prominently at the point when the light emission energy of the flash discharge tube 16 is at its maximum, and decreases as the distance increases before and after that point, but as can be seen from this figure, the operation settings are made to reduce the amount of flash light emission. The effect of excess light emission on the overall flash light emission becomes larger.
This causes a problem of excessive light intensity.

The above-mentioned excessive light emission is caused by the afterglow characteristics of the flash discharge tube 16 and the response delay of the control circuit.

The present invention has been developed in view of the above-mentioned problems, and is a method for comparing the integrated signal of an integrator that integrates the photoelectric conversion signal of flash light from a flash discharge tube with a reference signal. a flash light emitting device, comprising a light emitting amount control circuit that stops the flash light emitting operation of the flash discharge tube according to the output of the comparator, and changing the flash light emitting amount according to the operating setting value of the reference signal. A signal generating means for a correction signal to be integrated by the integrator together with the photoelectric conversion signal of the flash emission described above is provided, and the signal generating means is linked to the comparator, and the signal value of the correction signal is used as the reference signal of the comparator. The present invention proposes a flash light emitting device characterized in that the output of the comparator is set earlier in accordance with a correction signal for each flash light amount, which is determined in accordance with the surplus amount of flash light emission determined for each operation setting.

"Function" When the reference signal of the comparator is changed and the amount of flash light emission is manipulated and set, the correction signal value corresponds to this manipulation setting, and the correction signal corresponding to the surplus of flash light emission is integrated by the integrator.

Since this integrator integrates the photoelectric conversion signal of the flash light emission by adding it to the correction signal, the time point at which the output of the comparator is generated is earlier than the correction signal, and the excess light emission is corrected.

"Example" Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram of a flash light emitting device according to the present invention, and the same circuit components as those of the conventional circuit shown in FIG. 5 will be described with the same reference numerals.

Further, FIG. 2 is a time chart showing signal states in each part of the circuit.

In this circuit, block 42 is a correction signal generation circuit;
43 and 44 are one-shot multivibrators (hereinafter simply referred to as multi), block 45 is a regulator, 46 is a differentiation circuit, and 47 is a delay circuit, respectively. The correction signal generation circuit 42 is a pulse generator that is linked to the variable resistor 31 and outputs a correction signal S5 having a pulse width corresponding to the operation setting value of the reference signal S7, for example, receives the output of a differentiating circuit 46 and generates a predetermined pulse. This is a one-shot multivibrator that generates a width correction signal S5.

This circuit 42 operates in conjunction with the variable resistor 31 so that the correction signal S5 has a pulse width corresponding to the surplus amount of flash light emission according to the operation setting value of the reference signal S7, and also operates the correction signal S to flash. The signal is sent to the integrating capacitor 32 before the start of light emission.

The multi 43 forms a starting circuit that inputs a negative pulse signal S□ from the camera side, and is inverted by the falling edge of the pulse signal S input to the starting input terminal 48, and becomes Hi.
A signal S2 of gh level is output. The output signal S2 is set by the multifunction device 43 so that it continues for a period of time slightly longer than the full light emission time of the flash discharge tube 16, that is, the time until the flash light emission ends without light emission control.

The high level output signal S2 of the multi-channel 43 turns on the transistor 49, and then temporarily turns on the transistor 50 in the subsequent stage.

From this, the positive pulse signal S sent as the output of the transistor 50 is sent to the delay circuit 47, and this delay circuit 4
The 5CR 19, which receives the output signal 83' of 7 at its gate, becomes conductive, and the flash discharge tube 16 starts emitting flash light by the operation of the trigger circuit.

The delay circuit 47 delays the start of flash emission while the correction signal S is charged in the integrating capacitor 32.
After inputting the signal S, the output signal 83' is generated with a short delay time.
occurs.

On the other hand, the multi signal 44 to which the signal S2 is input is inverted by the rise of the signal S2, and outputs a low level signal S4.

This signal S4 is Lo during the full light emission time of the flash discharge tube 16.
It is set to continue at W level and is sent to the bases of transistors 34 and 35.

Therefore, the transistor 34 changes from OFF to ON, the transistor 35 changes from ON to 0FFL, and the phototransistor 33 becomes powered through the regulator 45. From this point on, the photoelectrically converted current of this phototransistor 33, which receives the light reflected from the subject due to flash emission, flows into the integrating capacitor.

Further, the output signal S2 of the multi 43 is input to the differentiating circuit 46, which is operated to cause the correction signal generation circuit 42 to output the correction signal S, as described above.

As described above, in this embodiment, the integral capacitor 32 is charged in advance with the correction signal Ss that corresponds to the surplus amount of flash light emission generated according to the set value of the reference signal S7, and then the phototransistor 33 controls the flash light emission. This integrating capacitor 32 is charged with a photoelectric conversion signal. Therefore, when the integrated signal S reaches the reference signal S7, the comparator 30 outputs the correction signal S5.
, and the occurrence of excess light emission is corrected.

Figures 3(,), (b), and (c) show the surplus light emission Q (shaded area) when the reference signal S7 is operated and set in three stages to change the flash light emission, and each of these flash light emissions. This figure shows the correction signal P that the integrating capacitor 32 charges in advance.

Although one embodiment has been described above, the present invention is particularly effective when implemented in a flash light emitting device that changes the reference signal S7 of the comparator 30 to set shooting conditions such as film sensitivity, aperture value, and light intensity correction. be. That is,
The setting of the signal value of the correction signal S can be made independent of the setting of the photographing conditions described above, which is extremely advantageous in terms of circuit configuration.

Note that the correction signal generation circuit 42 described above is not limited to the one that outputs the correction signal S in which the pulse width is changed, but also the correction signal that changes the pulse amplitude or the pulse width and amplitude according to the operation settings of the reference signal. Alternatively, the correction signal S may be integrated together with the photoelectric conversion signal of the flash light emission.

"Effects of the Invention" As described above, in the flash light emitting device according to the present invention, the correction signal corresponding to the surplus amount of flash light emission based on the set value is generated for each operation setting of the reference signal. It is integrated together with the converted signal by an integrator.

Therefore, the output generation point of the comparator that compares and outputs the integrated signal of the integrator with the reference signal is advanced in accordance with the signal value of the correction signal, thereby effectively improving the surplus of flash light emission.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a flash light emitting device showing an embodiment of the present invention, Fig. 2 is a time chart showing signal states of each part of the circuit, and Figs. 3 (a), (b), and (Q) are A diagram showing the surplus amount of flash light emission and the correction signal when the reference signal is changed to three levels. Figure 4 is a circuit diagram of a conventional flash light emitting device. Figures 5 (a), (b), ( c) is a diagram showing surplus light emission when the flash light emission of the conventional flash light emitting device is changed into three stages. 13... Converter 15... Main discharge capacitor 16... Flash discharge tube 22... Commutation capacitor 30... Comparator 32... Integrating capacitor 33... Phototransistor 42...Correction signal generation circuit 43.44...One-shot multivibrator 45...Regulator 46...Differentiating circuit 47...Delay circuit Patent applicant Stanley Electric Co., Ltd. Fig. 2 S Te

Claims (1)

[Claims] A light emission device that includes a comparator that compares an integrated signal of an integrator that is integrated as a photoelectric conversion signal of the flash light emission of the flash discharge tube with a reference signal, and stops the flash light emission operation of the flash discharge tube according to the output of the comparator. In a flash light emitting device comprising an amount control circuit and configured to change the amount of flash light emitted according to an operation setting value of the reference signal, the flash light emitting device includes signal generating means for generating a correction signal to be integrated by the integrator together with the photoelectric conversion signal of the flash light emission. At the same time, this signal generating means is linked to the comparator, and the signal value of this correction signal is determined in correspondence with the surplus amount of flash light emission determined for each reference signal operation setting of the comparator, and the signal value is determined at the time of output generation of the comparator. A flash light emitting device characterized in that the speed is accelerated according to a correction signal for each flash light emission amount.