JPS58102224A - Electronic flash device - Google Patents

Abstract

PURPOSE:To cause no photographing error even in case of a camera having no camera shake alarm informing means, by executing photometry of luminance of an object to be phtotgraphed, informing the low luminance in case of a prescribed value or below, also supplying a DC power supply to a main capacitor of an electronic flash device. CONSTITUTION:When a switch (S) 9 is turned on, a base current flows to a transistor (TR) 10 from a DC power supply 1, the TR10 is turned on, electric power is supplied to a photometric circuit 13, luminance of an object to be photographed is photodetected by a photodetector 11, and it is detected by a luminance level detecting circuit 12. In a state that there is the possibility of causing a camera shake due to a low detecting level of luminance of the object to be photographed, the fact that light emission of a flash tube 7 is required is informed by an alarm informing circuit 8, by an output signal from the circuit 2 is also operated, the electric power supply 1 is supplid to a DC-DC converting circuit 3, and a main capacitor 4 is charged. When a trigger S5 is turned on after prescribed charging, a triggering circuit 6 is operated, the flash tube 7 emits light, and flash photographing is executed. In this wya, photographing error can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electronic flash device that receives object light and automatically controls the amount of light emitted, and in particular, a main capacitor that measures the brightness of the object and supplies light emission energy to the flash tube when the brightness of the object is below a predetermined level. This invention relates to an electronic flash device that automatically supplies power to the electronic flash device and enables flash photography.

Conventionally, the brightness of the subject is photometered, and if the brightness is below a predetermined value, there is a risk of camera shake. Cameras with built-in flash devices are known.

However, some of these cameras do not have such a warning function, and there is always a risk of photographing with camera shake depending on the brightness of the subject.

Therefore, the present invention was created in view of the above problem, and uses an electronic flash device, which is indispensable for taking photographs in dark subjects, to measure the brightness of the subject, thereby reducing the risk of camera shake when the predetermined brightness level is low. indicates that there is, and
The purpose of the present invention is to provide an electronic flash device that automatically supplies power to an electronic flash device to enable flash photography and prevents erroneous photography even in the above-mentioned camera, and will be described below with reference to the drawings.

FIG. 1 shows an electric circuit diagram of an embodiment of the electronic flash device of the present invention. In the figure, when switch 9 is turned on, a pace current flows from DC power supply 1 to transistor 10, and transistor 10 is turned on. Power is supplied to the photometry circuit 13 from the DC power source 1, the subject brightness is received by the light receiving element 11, and the brightness level detection circuit 12 performs level detection.

Now, when the subject brightness detection level is low and there is a risk of camera shake, the output signal from the brightness level detection circuit 12 indicates that the subject brightness level is low and the flash tube 7
A warning notification circuit 8 notifies that the light needs to be emitted.

At the same time, the power supply control circuit 2 also operates, and the DC power supply 1 is
As is well known, the main capacitor 4 is charged by supplying it to the C-DC converter circuit 3, and when the trigger switch 6 is turned on after the specified charge, the trigger circuit 6 is activated and the flash tube 7 emits light to perform flash photography. It will be done.

FIG. 2 shows an electric circuit diagram of another embodiment of the present invention,
The warning notification at the time of low brightness is performed in conjunction with the charging of the main capacitor, and as mentioned above, at the same time as the warning notification circuit 8 issues the notification at low brightness, charging of the main capacitor 4 is started, and the charging voltage increases. When the flash tube 7 is charged to a voltage that allows it to emit light.

A signal is generated from the voltage detection circuit 14 and applied to the warning notification circuit 8, whereby the warning notification is stopped by 1°.

Therefore, the notification by the warning notification circuit 8 has the advantage of not only notifying the danger of camera shake due to low brightness, but also notifying the completion of charging of the main capacitor 4 when the notification ends.

FIG. 3 shows an electric circuit diagram of still another embodiment of the present invention, and parts with the same numbers as those in the previous embodiment have the same functions, so no special explanation will be given.

In the figure, after the main capacitor 4 has been charged at low brightness, the trigger circuit 6 is operated to cause the flash tube 7 to emit light. From then on, the supply to the photometric circuit 13 is stopped. The power supply voltage generation circuit 17 operates as the flash tube 7 emits light, and the power generated by this circuit is applied to the photometry circuit 13, and the subject light is received by the light receiving element 11 and integrated by the photocurrent integration circuit 18. When the integral value reaches a predetermined value, a light emission stop signal is issued, which causes the light emission control circuit 16 to operate and stop light emission. In this embodiment, the photocurrent integration circuit 18 performs integration also during brightness detection, but this integrated amount is emitted during the operation of the trigger circuit and is used to supply power to the photometry circuit 13 in response to one light emission. By operating at times.

Alternatively, by making the photocurrent integration circuit 18 inactive during brightness level detection and operating in conjunction with the operation of the trigger circuit, it is possible to perform an error-free integration operation. Further, the notification by the notification circuit can also be controlled in association with the charging of the main capacitor, as in the previous embodiment.

In the above embodiment, only the case where the subject is of low luminance has been mentioned, but when the subject is of high luminance, the notification circuit 8. The power supply control circuit 2 does not operate at all, and therefore, in this case, it is reported that there is a subject at a high brightness level.

As described above, the auto-adjustable electronic flash device of the present invention has the function of detecting the brightness of the subject and notifying the necessity of firing the flash tube due to the risk of camera shake in the case of low brightness. 1. This is effective for cameras that do not have camera shake warning notifications.

[Brief explanation of the drawing]

FIG. 1 shows an electric circuit diagram of one embodiment of the automatic dimming electronic flash device of the present invention, FIG. 2 shows another implementation circuit diagram, and FIG. 3 shows still another implementation circuit diagram. show. 1...DC power supply, 2...Power supply control circuit, 3...DC-DC-7 amplifier circuit, 4
... Main capacitor, 6 ... Trigger circuit, 7 ... Flash tube, 8 ... Warning circuit, 10 ... Transistor, 13. ...Photometering circuit, 14...Voltage detection circuit, 16...
...Power supply switching circuit, 16...Light emission control circuit, 17...Power supply voltage generation circuit, 18...
・Photocurrent integration circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Cause Figure 2 Figure 3

Claims (3)

[Claims] (1) In an electronic flash device that causes a flash tube to consume charging energy of a main capacitor charged from a DC power source to emit light, the electronic flash device includes a circuit that has a light receiving element and measures the brightness of a subject, and a circuit that measures subject brightness when the subject brightness level is below a predetermined value. a circuit that is operated by being supplied with an output signal emitted from the photometric circuit when the brightness level is below a predetermined value to notify low brightness; An electronic flash device comprising a power supply control circuit for supplying power. (2) The electronic flash according to claim 1, further comprising a voltage detection circuit that detects the charging voltage of the main capacitor and stops the notification operation of the notification circuit when the voltage reaches a predetermined value. Device. (3) The supply of the DC power to the circuit that generates a power supply voltage when the flash tube emits light and the photometry circuit when the flash tube emits light is stopped, and the power supply voltage from the power supply type pressure generating circuit is reduced. a power switching circuit that applies power to the photometric circuit;
a circuit that integrates a photocurrent of the light receiving element that receives light reflected from a subject due to light emission from the flash tube; 2. The electronic flash device according to claim 1, further comprising a light emission control circuit for stopping light emission of the flash tube.