JPS63104035A - Flashing device - Google Patents

Abstract

PURPOSE:To execute a flash light emission in a short period after a start of charging in case a set guide number has been made small, and to enlarge a photographing chance, by setting a charging completion detecting level in accordance with the set guide number. CONSTITUTION:A charging state of a main capacitor 5 is detected by a comparator 24, and when it reaches a prescribed value, an output of the comparator 24 becomes a high level. A resistance 9 is interlocked with a dial 29, and when a numeral 1/1 of the dial 29 is set to an index 29', the resistance value becomes the highest value, and unless a charging voltage V of the main capacitor 5 becomes high, the output of the comparator 24 is not shifted to a high level. The charging voltage for setting the light emission quantity to 1/2 becomes 2<-1/2> times, therefore, a resistance value of a variable resistance 9 is interlocked with the dial 29 and varied so as to satisfy its condition. In this way, in accordance with the light emission quantity which has been set by the dial 29, its charging completion state detecting level is varied, and as the light emission quantity is further lowered, the comparator 24 is inverted to a high level in a short period.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flash device with variable guide number.

[Prior art]

Conventionally, flash devices with variable guide numbers are known, but in these conventional devices, even if a low guide number is set, the charging voltage of the main capacitor is higher than the charging voltage required for the guide number. It was not possible to perform flash photography until the voltage was reached.

In other words, in a flash device, in order to cause the flash tube to emit light regardless of the guide number, it is necessary to apply a minimum light emission voltage of a predetermined level to the flash tube, and for this reason, the main capacitor must be charged to the minimum light emission voltage or higher. It was necessary to wait for the light to start emitting light.

With this type of device, as described above (because it cannot emit light until the main capacitor reaches the above minimum light emission voltage), the charge completion detection level must be set above the above minimum light emission voltage (regardless of the guide number, for example). Even if a low guide number is set, it takes a long time for the charging completion lamp to turn on and notify the photographer that the flash is ready to fire, resulting in inconveniences such as missing a photo opportunity. was.

In order to solve the above problem, for example, Japanese Patent Application Laid-Open No. 58-970
As shown in No. 35, a small-capacity auxiliary capacitor is provided in addition to the main capacitor, and this capacitor is charged in advance to the minimum luminous voltage. By applying this to the flash tube, the voltage of the main capacitor reaches the above-mentioned minimum. A flash device has been proposed that is capable of emitting light even without being charged to a light-emitting voltage.

However, this flash device only allows light emission before the main capacitor is charged to the above-mentioned minimum light emission voltage, and the charging completion detection level is not corrected in relation to the setting guide number, so the charging completion display is displayed. Due to the relationship with the guide number, when the number is set to a low value, it cannot be done in a short time, and the photographer has to wait longer than necessary for the main capacitor to be charged before he or she can start shooting.

〔the purpose〕

The present invention has been made in view of the above matters, and provides a flash device that sets a charging completion detection level according to a set guide number and issues a charging completion instruction in a short time when the guide number is low. That is.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of a flash device according to the present invention. In the figure, l is the power battery, 2 is the power switch,
3 is a DC/DC converter that boosts the output of battery l;
5 is a main capacitor charged by the output of the DC/DC converter. Reference numeral 4 denotes a constant voltage circuit that forms a reference constant voltage based on the output of the battery 1, and the output of this circuit is applied to a voltage dividing circuit consisting of a resistor 8 and a variable resistor 9, which applies a reference voltage to one input terminal of the comparator 24. are doing. 6 and 7 are resistors, and the resistors 6 and 7 divide the charging voltage of the main capacitor and transmit the charging voltage information of the main capacitor to the input terminal of the comparator 24. 12 is a display LED that emits light at the output of the comparator 24; 13 is a transistor whose base is connected to the output of the comparator 24; the collector of the transistor is connected to a terminal on the camera side via a terminal (not shown); It notifies the camera that the main capacitor has been fully charged, and switches the camera's shutter and aperture control mode to flash mode, for example. Reference numeral 16 denotes one circuit of a known trigger; 30 a semiconductor switch that is turned on in response to the output of the comparator 24; the trigger circuit is connected to a synchro switch on the camera side through the switch 30 and a terminal (not shown); ing. 17 is a flash tube that is triggered by a single circuit of birds;
Reference numeral 18 denotes a light receiving element disposed near the flash tube 17 to receive light from the flash tube. Reference numeral 19 denotes a capacitor charged by the output of the light receiving element. The light receiving element and the condenser form a dimming timer. 20 is a semiconductor switch that is turned off for a certain period of time by a signal output from the trigger circuit in synchronization with the trigger of the flash tube 17 by one circuit; 25 is a comparator;
A reference voltage from a voltage dividing circuit is applied thereto, and at the same time, the output of the dimming timer is applied thereto. 2
1 is the flash tube 17 in response to the output J of the comparator 25.
This is a control circuit composed of a known commutation circuit that cuts off the discharge path. 28 is a high voltage power source; 26 is a small capacity auxiliary capacitor charged by the high voltage power source; this capacitor is constantly charged by the high voltage power source to a high voltage that enables the flash tube to emit light.

15 is a backflow prevention diode provided between the main capacitor 5 and the auxiliary capacitor 26.

29 is an operation dial for setting a guide number, and numbers are attached to the dial. This number means that the guide number is set to half of 1/1 when it is 1/2 based on 1/1, and the numbers shown below as 1/4, 1/8, etc. are 1/1. It means the set value of the standard guide number.

The variable resistors 9 and 23 are interlocked with the dial 29 to make their resistance values variable.

Next, the operation of the embodiment shown in FIG. 1 will be explained.

When power switch 2 is turned on, the voltage from battery 1 becomes DC.
- The DC converter 3 boosts the voltage, and the main capacitor 5 is charged with the boosted voltage. The charging state of the main capacitor 5 is detected by a comparator 24, and when the charging voltage reaches a predetermined value, the output of the comparator 24 becomes high level. At this time, as mentioned above, the resistor 9 is linked to the dial 29, and when the number 1/1 on the dial 29 is set to the index 29', its resistance value is the highest value, and the resistance value of the main capacitor -5 is the highest value. The output of the comparator 24 will not shift to high level unless the charging voltage V becomes high, but by setting the number on the dial 29 to a value other than 171, the comparator 24 will switch to high level when the corresponding charging voltage is reached. do. In other words, the stored energy of the main capacitor is expressed as 1/2 CV2 (C...capacity of capacitor 5 iV...charging voltage), and if the amount of light emitted when the number is set to 1/1 is 1, then The charging voltage V of the main capacitor when the amount of light emission is reduced to 1/2 is 1/f
The charging voltage V of the main capacitor when the light emission amount is doubled and the light emission amount is 1/4 is 1 compared to the voltage V when the light emission amount is 1.
The charging voltage to reduce the amount of light emission to 1/2 is 1/2.
Since it is multiplied by f2, the resistance value of the variable resistor 9 changes in conjunction with the dial 29 so as to satisfy this condition.

Therefore, the charging completion state deafness detection level changes according to the amount of light emitted by the dial 29, and the lower the amount of light emitted, the more quickly the comparator 24 is inverted to a high level.

In this manner, when the output of the comparator 24 becomes high level, the LED 12 lights up to indicate that charging is completed, and the transistor 13 is turned on to switch the camera mode to flash mode. Further, the high level of the comparator 24 is transmitted to the semiconductor switch 30, which turns on the switch.

In this state, when the camera is released and the synchro switch is turned on, a synchro switch on signal is transmitted to the trigger circuit 16 via the switch 30.

As mentioned above, the charging voltage of main capacitor 5 is dial 29.
On the other hand, in order to cause the flash tube to emit light, a voltage higher than the predetermined minimum light emission voltage must be applied to the flash tube 17. (If the light emission amount is set using the dial 29, the charging voltage of the main capacitor will be lower than the above minimum light emission voltage, and the flash tube 17 will not emit light even if the on signal of the synchro switch is transmitted to one circuit as described above. There is a risk.

In order to solve this problem, in the present invention, a small-capacity auxiliary capacitor 26 is provided, which is charged with a voltage higher than the above-mentioned minimum light emission voltage by a high-voltage power supply 28, and the voltage of the capacitor 26 is used to increase the charging voltage of the main capacitor. Luminescence is guaranteed even when the temperature is low.

As described above, when the on signal of the synchro switch is transmitted to the trigger circuit 16, the flash tube 1
7 is triggered and flash light emission starts. In addition, the switch 20 is turned off in synchronization with the trigger operation of the trigger circuit 16, and the light receiving current of the light receiving element 18 is applied to the capacitor 19.
starts charging. Since the light receiving element 18 directly receives the flash from the flash tube 17, the charging potential of the capacitor 19 represents the amount of light emitted, and when the voltage of the capacitor 19 reaches a predetermined value, the comparator 25 outputs a high level. Then, the control circuit 21 is activated to stop the flash.

At this time, since the resistance value of the resistor 23 is linked to the dial 29, the level corresponding to the set light emission amount is determined by the comparator 2.
5, and the flash will be stopped when the set amount of light is reached.

In the embodiment, the value of the resistor 9 is set based on the relationship between the charging voltage V of the main capacitor 5 and the set amount of light emission, but the flash tube 17 is provided with a voltage equal to or higher than a predetermined voltage (light emission sustaining voltage) after being released. If not, the light emission cannot be maintained, so when setting the resistance value, it is necessary to set the resistance value by adding the sustaining voltage to the above charging voltage of the main capacitor to make the set light emission amount. .

Also, the auxiliary capacitor 26 is charged from the high voltage power supply 28, but instead of this, the main capacitor can be charged by D
Before charging with the C-DC converter, the auxiliary capacitor may be charged first, and then the main capacitor may be charged.

Alternatively, the display means on the camera side may be turned on when the transistor 13 is turned on.

Furthermore, the circuit for controlling the amount of light emitted to a set value may prohibit charging of the main capacitor in response to the high level of the comparator 24, and may be configured to emit full light at the time of flash light emission.

〔effect〕

As described above (the present invention is a strobe with a variable guide number, the charging completion detection level is set according to the set guide number, so if the set guide number is small, the flash will emit light in a short time from the start of charging. This can be done and the effect of increasing photo opportunities can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a flash device according to the present invention. 9.23...Variable resistor, 5,26...Capacitor, 24...Comparator, 12...LED
. 29...Dial.

Claims (1)

[Scope of Claims] A main capacitor that accumulates flash charge, a detection circuit that detects the charge level of the main capacitor and outputs a charge completion signal to cause a charge completion instructing means to issue a charge completion instruction, and a detection circuit that detects the amount of light emitted. a light emission amount variable setting member that variably sets the light emission amount; a light emission amount control circuit for discharging the charge of the main capacitor to the flash tube according to the light emission amount set by the setting member; an auxiliary capacitor that is charged with a voltage and applies the voltage to the flash tube; and an adjusting means that adjusts the detection level of the detection circuit in accordance with the light emission amount set by the light emission amount variable setting member. A flash device featuring