JPS6136985Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic flash device that receives reflected light from a subject, stops a flash discharge tube from emitting light, and displays the reflected light.

A first switching element is connected in series to the flash discharge tube, and both are activated at the same time to start the flash discharge tube's light emission.Then, the second switching element in the arc extinguishing circuit is activated to reduce the amount of light accumulated in the commutation capacitor. 2. Description of the Related Art A dimming type electronic flash device is known in which the light emission period of the flash discharge tube is regulated by causing charges to flow in the opposite direction to a first switching element and making the first switching element non-conductive.

The means for activating the second switching element of the arc extinguishing circuit includes outputting the second switching element after a set time from the start of light emission regardless of the distance between the camera and the subject.
There is a light intensity setting section that activates the second switching element, and a light receiving section that receives the reflected light from the subject due to light emission from the flash discharge tube, outputs it, and activates the second switching element, and both can be used selectively. be done. However, when selectively using the light receiving section, a display circuit is sometimes used that lights up to indicate when an appropriate amount of light (depending on the state of charge of the main capacitor) is emitted from the flash discharge tube. However, since this display circuit is activated by the output of the light receiving section, if the output of the light receiving section and the output of the light amount setting section are simply led to the extinguishing circuit, the output terminal of the light amount setting section will also display the display. This is inconvenient because it starts up the circuit.

In other words, in the case of automatic light adjustment using the output of the photoreceptor, the correct exposure may not be obtained when the distance to the subject is fast, but the photographer cannot know whether or not the correct exposure has been obtained. Therefore, it is desirable to indicate this by some means. The above display circuit provides a concrete means for this purpose.

On the other hand, when manual light adjustment is performed using the light amount setting section, the photographer usually recognizes the appropriate light emission amount (light emission period) from a guide number or the like, sets the light emission amount, and then starts the light emission. Furthermore, in some cases, inappropriate exposure may be intentionally applied for the purpose of obtaining special photographic effects. However, in the case of manual dimming, the output is always generated from the light intensity setting section, so if the display circuit is started with the output from here,
This display is always made regardless of whether proper exposure has been obtained. Therefore, such a display is not only meaningless, but also confuses the photographer, which is not desirable.

The present invention has been developed in view of the above-mentioned points, and provides an electronic flash device in which only the arc extinguishing circuit is activated by the output of the light amount setting section, and both the arc extinguishing circuit and the display circuit are activated by the output of the light receiving section. It is something to do.

The details of the present invention will be explained below based on one embodiment shown in the drawings. In the figure, 1 is a main capacitor charged to the polarity shown, 2 is a flash discharge tube such as a xenon tube,
Reference numeral 3 designates a first switching element such as a silicon-controlled rectifying element, and the flash discharge tube 2 and the first switching element 3 connected in series are activated at the same time.

Reference numeral 4 designates an arc extinguishing circuit for the first switching element 3, which conducts the charge of the commutation capacitor 43 charged to the illustrated polarity through a path including resistors 41 and 42 to a second switching element 44 such as a cold cathode thyratron. This causes the current to flow in the opposite direction to the first switching element 3, making it non-conductive. In the second switching element 44, when the silicon-controlled rectifying element 45 becomes conductive, the electric charge of the capacitor 47 that has been charged in advance flows through the resistor 46 to the primary winding of the transformer 43, and the electric charge is generated in the secondary winding. It is activated by high voltage.

5 connects the capacitor 52 to the resistor 54 to the neon lamp 55 to the resistor 56 by conducting the charge pre-charged in the capacitor 52 via the resistor 51 through the silicon-controlled rectifying element 53 which is a starting element.
This is a display circuit that flows through the path of the silicon-controlled rectifying element 53 and lights up the neon lamp 55. The capacitor 57 is used to make the display on the neon lamp 55 blink by oscillation, and the capacitor 58 is charged through the resistor 59, and when the silicon-controlled rectifying element 53 becomes conductive, the charge is immediately discharged and the capacitor 58 becomes empty. This is to ensure a discharge path for the capacitor 52 even if the silicon-controlled rectifying element 53 is subsequently turned off. Its capacity is therefore selected to be equal to that of capacitor 52.

6 is a light amount setting unit that directly receives the light emitted from the flash discharge tube 2 and outputs the output after a set period from the start of light emission of the flash discharge tube 2; This is a light-receiving section that performs photometric integration and generates an output when the integrated value reaches a predetermined value, and both are used selectively by a switch or the like. Reference numeral 8 denotes a control circuit that activates only the arc extinguishing circuit 4 with the output of the light amount setting section 6, and activates both the arc extinguishing circuit 4 and the display circuit 5 with the output of the light receiving section 7. That is, the output of the light receiving section 7 is once received by the transistor 81, and the output of the transistor 81 is applied to the gate of the silicon-controlled rectifier 53 and also to the gate of the silicon-controlled rectifier 45 via the diode 82. A diode 82 prevents the output of the light amount setting unit 6 guided to the gate of the silicon control rectifying element 53 from going around to the gate of the silicon controlled rectifying element 53.

In the electronic flash device configured as described above, when the light receiving section 7 is used, when the flash discharge tube 2 and the first switching element 3 are activated simultaneously in conjunction with the shutter of the camera, the main capacitor 1 is The flash discharge tube 2 starts emitting light due to the charge. When the light receiving section 7 receives the reflected light from the subject, the control circuit 8 and the arc extinguishing circuit 4 stop the flash discharge tube 2 from emitting light, and at the same time, the display circuit 5 displays a blinking display for a certain period of time indicating that proper exposure has been achieved. It will be done.

On the other hand, when using the light amount setting section 6,
The display circuit 5 does not operate, and only the arc extinguishing circuit 4 is activated after a set time from the start of light emission to stop the flash discharge tube 2 from emitting light.

As described above, with the electronic flash device of the present invention, by simply adding a simple control circuit mainly consisting of a directional element (diode 82), the display circuit can operate only when the light receiving section is used, and proper exposure can be achieved. It is possible to display whether or not the amount of light has been set, and the display circuit is not operated unnecessarily when the light amount setting section is used.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be implemented with various modifications.

[Brief explanation of the drawing]

The figure is a circuit configuration diagram showing an embodiment of the present invention. 1... Main capacitor, 2... Flash discharge tube, 3...
...First switching element, 4... Arc extinguishing circuit, 4
DESCRIPTION OF SYMBOLS 1... Second switching element, 5... Display circuit, 6... Light amount setting section, 7... Light receiving section, 8... Control circuit.

Claims (1)

[Scope of utility model registration request] In an electronic flash device in which a first switching element is connected in series with a flash discharge tube, and a light emission period of the flash discharge tube is controlled by a conduction period of the first switching element, the second switching element is activated. an arc-extinguishing circuit that causes the first switching element to become non-conductive; a light amount setting section having an output end coupled to the arc-extinguishing circuit and generating an output after a set time from the start of light emission of the flash discharge tube; A light receiving part is connected to the output end of this light receiving part, which photometrically integrates the reflected light from the subject due to the light emitted by the discharge tube and generates an output when the integrated value reaches a predetermined value. a display circuit that emits light for a certain period of time, and a directional element connected between a connection point between the display circuit and the light receiving section and a connection point between the extinguishing circuit and the light amount setting section; a control circuit that transmits the output to the arc extinguishing circuit via the directional element and prevents transmission of the output of the light amount setting section to the display circuit,
An electronic flash device characterized in that both the arc extinguishing circuit and the display circuit are activated by the output of the light receiving section, and only the arc extinguishing circuit is activated by the output of the light amount setting section.