JPS6122761A - Power source of photographic strobe device - Google Patents

Abstract

PURPOSE:To obtain a low DC voltage source efficiently from a laminated battery by converting a DC high voltage once into an AC, supplying it to a transformer to drop the voltage, and using it as a drive power source for an IC circuit. CONSTITUTION:A power source of a photographic strobe device has a high voltage power source A and a strobe device body B, further resistors 7, 8, capacitors 9, 10, a switching transistor 11, a converter transformer 12 made of the primary and secondary windings 12a, 12b, a rectifying diode 13, and a smoothing condenser 14 to form a DC/DC converter, thereby obtaining a low voltage DC power source form a laminated battery 1. The output of the secondary winding 12b is AC-fed back through the capacitor 10 to the base of the transistor 11. The output is supplied through the diode 13 to the capacitor 14, and a predetermined voltage is obtained between terminals G and F.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a power supply device for a photographic strobe device, and more particularly to a power supply device that obtains a low-voltage DC power source from a high-voltage DC power source.

Conventional configurations and their problems Among photographic strobe devices that are useful as artificial light sources during photography, those that emit a relatively large amount of light are designed to shorten the flash interval, increase the number of flashes, or take into account economic efficiency. Most of them are commercial power sources, DC low voltage power sources, and so-called dry batteries7.
It is configured so that various power sources can be used, such as a DC high voltage power source, so-called high voltage stacked battery.

On the other hand, in recent years, some strobe devices not only emit light, but also can send and receive signals to and from the camera, and some display shooting information such as aperture value using display elements such as liquid crystals. It is emerging.

If we look at the structure for transmitting and receiving signals or displaying information as described above, it is an electric circuit structure mainly consisting of an IC circuit.

Therefore, in such a case, a DC voltage power source of several volts and several milliamperes is required in addition to the power source for the light emitting operation described above.

That is, in recent years, photographic flash devices have come to be equipped with a DC high-voltage power source for emitting light, and a DC low-voltage power source for driving IC circuits and the like that perform other additional operations.

Now, if we consider the power source for driving the above-mentioned IC circuit, etc., for example, in a type of strobe device in which the DC high-voltage power source for light emission is obtained from a dry cell battery that is a DC low-voltage power source and a DC-DC converter circuit. Yes, DC-D
C: The dry battery that is the power source for the converter circuit is -1:1
It can be used, and there is no big problem with %, and even if you use a power supply that uses commercial power, you can easily obtain a low voltage, so no problem will occur as well.

However, in the case where the power supply device for the light emitting device is a high-voltage DC power source that uses a laminated battery, attempting to obtain a DC low voltage rather than a DC high voltage simply by voltage division will result in an extremely large power loss, and the conversion efficiency will be 1. It becomes extremely bad at ~2%, making it extremely difficult to put it into practical use.

For this reason, in the case of conventional strobe devices, the above-mentioned problems are addressed by using dry batteries, which are DC low-voltage power sources, at the same time as laminated batteries.

Therefore, sufficient power can be supplied to IC circuits, etc. without any problem, but there are new problems that cannot be considered because the consumption characteristics of the laminated battery and the low voltage battery are different. Therefore, improvements are currently desired.

OBJECTS OF THE INVENTION An object of the present invention is to provide a power supply device for a photographic strobe device that takes into account the problems of the conventional devices as described above and can obtain a low-voltage DC power source extremely efficiently from a stacked battery that is a high-voltage DC power source. That's true.

Another object of the present invention is to provide a power supply device for a photographic strobe device that includes a so-called DC-DC converter circuit that obtains a DC low-voltage power source by once converting a DC high voltage into an AC voltage, supplying it to a transformer, and stepping down the voltage. It is.

DESCRIPTION OF EMBODIMENTS FIG. 1 is an electric circuit diagram showing an embodiment of a power supply device for a photographic strobe device according to the present invention. A high voltage power supply section consisting of a power switch 3, B is a main capacitor 4. Flash discharge tube6. The main body of the strobe device including the trigger circuit 6 and the like is shown, and c, c', D, and D' are connection terminals for connecting the high voltage power supply unit and the main body B of the strobe device.

7 and 8 are resistors, 9 and 10 are capacitors, 11 is an NPN switching transistor, 12 is a converter transformer consisting of a primary winding 12a and a secondary winding 12t), 13 is a rectifier diode, and 14 is a smoothing capacitor, respectively. Show and know.

Note that, as is clear from the connection relationship shown in FIG.
In other words, the secondary winding 112b is connected to the base of the NPN transistor 11 via the capacitor 10, so that the secondary winding 112b is connected to the base of the transistor 11 through the capacitor 10.
It is needless to mention in detail that the output of the circuit is configured so that the output is fed back to AC.

Now, if the power switch 3 is turned on with the high-voltage power supply A and the strobe device main body B connected through the connection terminals c, c' and D, D', the current limiting resistor is removed from the stacked battery 1. 2. Resistance 7, 8. Since current flows through the capacitor 9, the base of the switching transistor 11 becomes forward biased and tends to become conductive.

When a base current flows to the base of the transistor 110 and it begins to become conductive, the primary winding 12 of the converter transformer
? Since current flows in the direction of the arrow X between the corephtal emitters of this transistor 11, the secondary winding 12b
A voltage of the polarity shown is induced to cause a current to flow in the direction of the arrow Y.

The voltage generated in the secondary winding 12b is
0 to the base of the transistor 110, and the rectifying diode 13 to the smoothing capacitor 1.
4, the transistor 11 which is about to become conductive is completely rendered conductive, and at the same time charging of the smoothing capacitor 14 is started.

After the transistor 11 is made conductive, when the current in the direction of the arrow X ceases to flow in the primary winding 12a due to saturation of the l-lance 12, current is induced to flow in the direction of the arrow Y in the secondary winding 12b. The voltage 1 disappears, and on the contrary, the energy stored during the induction is released. That is, a so-called back electromotive force, which is a voltage in a direction opposite to the illustrated polarity, is generated that causes current to flow in the secondary winding 12b in the Z direction opposite to the Y direction of the arrow.

As is clear from FIG. 1, this back electromotive force causes a reverse bias between the base and emitter of the transistor 11 via the capacitor 10, so that the transistor 11
becomes completely non-conductive at the saturation point.

After that, when the energy of the above-mentioned back electromotive force decreases,
The transistor 11 is a stacked battery 1. Resistance 2.7, 8. Due to the action of the capacitor 9, the capacitor 9 attempts to become conductive again, and the operation as described above is performed again.

Now, when looking at the output waveform of the secondary winding 12b, that is, the waveform between E-1 in FIG. 1, the waveform was as shown in FIG. 2.

That is, time t is the time when the power switch 3 is turned on.

, a predetermined voltage "V" determined by the turns ratio between the primary winding 12'a and the secondary winding 12b is generated between E and F, and at a certain time t when the converter transformer 12 is saturated, Thereafter, a back electromotive force was generated until the transistor 11'' became conductive again.

As a result, since the output as described above is supplied to the smoothing capacitor 14 via the rectifying diode 13, the voltage between both ends of the smoothing capacitor 14, that is, between G-1 and G-1 is at the time t.

From then on, the above-mentioned predetermined voltage (2) is almost always obtained.

Therefore, if the turns ratio of the primary winding 12& and the secondary winding 12b of the converter transformer 12 is set so that, for example, several volts can be obtained as the predetermined voltage V, the voltage across the smoothing capacitor 140 can be adjusted to This means that it can be used as a power source for circuits, etc.

It goes without saying that the predetermined voltage V can be set to a desired voltage value by appropriately setting the turns ratio, and the energy conversion efficiency can also be improved by several tens of percent by using the converter transformer 12. There is no need to explain in detail that it can be ranked higher.

Furthermore, in the embodiment shown in Fig. 1, the main parts such as a controller transformer and a smoothing capacitor are provided in the strobe device main body B, but they are provided in the power supply part A to supply only the necessary low DC voltage. It is also clear that it can be constructed such that the light is supplied to the strobe device main body B via the connection terminal.

[Brief explanation of the drawing]

FIG. 1 is an electrical circuit diagram showing an embodiment of a photographic flash device according to the present invention, and FIG. 2 shows an output waveform of the secondary winding 12b in FIG. 1...Stacked battery (DC high voltage power supply), 2...
...Current limiting resistor, meter...Power switch, 7,
8...Resistance, 9.10...Capacitor, 1
1...Switching transistor, 12a...
...Primary winding, 12b...Secondary winding.

Claims (2)

[Claims] (1) An oscillating section that oscillates when DC voltage from a DC high-voltage power supply is supplied, consisting of a primary winding, a switching transistor, etc.; a secondary winding that is electromagnetically coupled to the primary winding of the oscillating section; and A DC that obtains a direct current low-voltage power source directly from the direct current high-voltage power source, which is composed of a voltage converter section consisting of a rectifying diode that rectifies the voltage generated in the winding, and a smoothing capacitor that smoothes the voltage outputted via the rectifying diode. - A power supply device for a photographic strobe device equipped with a DC converter circuit. (2) The oscillator is a first,
A series body of a second resistor and a first capacitor, and a base ~
the emitter is connected to both ends of the first capacitor,
an NPN switching transistor whose collector is connected to the connection point of the first and second resistors via a winding; and one end of the voltage converter that is in opposite phase to one end of the winding and the base of the transistor. 2. A power supply device for a photographic strobe device according to claim 1, comprising a second capacitor for AC feedback provided in between.