SU321967A1 - DEVICE FOR SYNCHRONIZATION IGNITION OF PULSE LAMP - Google Patents

Description

The invention relates to the field of photographic equipment and can be applied when using an electronic photo flash in photographs.

Using flash units is difficult for two reasons:

To power a flash lamp, a high-capacity power supply is needed, which can provide, at least briefly, a current of several hundred amperes;

the lamp should be lit at a strictly defined point in time, consistent with the work of the camera shutter.

To reduce the internal resistance of the current source, an energy storage device, a high-capacity electric capacitor, is introduced into the photo flash circuit. The capacitor is charged from the battery before shooting, and during exposure it is discharged and gives up stored energy.

These devices are characterized by relatively large dimensions and weight, due to the presence of a capacitor and the need for frequent battery changes.

These drawbacks are eliminated by excluding the storage capacitor and battery and using an AC lighting network to power the device. However, it is difficult to synchronize the flash with the shutter of the camera.

After charging the storage capacitor, the DC flash is ready for operation. This facilitates the ignition of the flash lamp at the right time and simplifies the construction of the synchronization device.

In contrast, in an alternating current flash, a flash lamp can flash only at times when the instantaneous mains voltage is close to the maximum value. If the flash lamp is ignited somewhat earlier or after these moments, the lamp will not flash. Therefore, when building a synchronization device for a variable flash

current there are great difficulties. To eliminate them, the known device, besides raising it, its lamp-type transformer contains a circuit for selecting the moment when the mains voltage passes a maximum made on a cold cathode thyratron. In addition, to work with this photo flash, it is necessary that the closing time of the photocontact sync contact be longer than the network period.

During the filming, two or more flashlights are often used at the same time, which makes it possible to increase the illumination of the subject and improve the artistic quality of the pictures (the formation of shadows). With this one

with a photo camera, and additional - provide a light synchronizer, which perceives the light of the main lamp and ignites through the source of clock pulses n the ignition unit connected to it lamp. The photocell's illumination with the light pulse of the main photo flash produces a voltage pulse that is applied to the control electrode of the thyratron in the ignition circuit of the flash lamp and ignites it.

However, the known light synchronizers can only be used in direct current flash units. During the operation of the light synchronizer in the AC flash, it is necessary to record two events — the flash of the main lamp and the maximum of the mains voltage — and only when they coincide, set the flash lamp.

However, an AC flash as an additional light source has several advantages over DC flash: smaller dimensions and weight; does not require replacement of the power supply; allows the shooting process to take place in a shorter time.

The purpose of the present invention is to further synchronize, following the maximum amplitude of the AC voltage in the presence of a flash of the main lamp.

This goal is achieved by inserting a dual synchronization circuit with the main lamp and a network voltage into the light synchronizer.

The light pulse created by the main lamp prepares the network synchronization circuit for selecting the maximum voltage of the network. Ignition of the additional lamp occurs at the moment when this maximum is reached.

This embodiment of the synchronization circuit allows the use of an alternating current flash as an additional light source.

The electrical circuit of the described device is shown in the drawing.

The device consists of a source of clock pulses from a DC lamp on a photodiode (photoresistor) / and a cold cathode 2 thyratron. In parallel with the thyratron 2, a memory capacitor 3 is switched on. The power to the thyratron 2 is supplied from an alternating current network through the diode 4. The cathode of the thyratron is connected to the negative of the network through a resistor 5 and to the control electrode of the thyratron 6 of the ignition unit for an additional pulse lamp.

The capacitor 7 provides the necessary DC pulse energy, and the transformer 8, which is inserted into the cathode of the thyratron 6, produces an IGNITION of the pulse lamp 9. The device is powered by an AC network 10. The terminals 11 are used to operate from a camera synchronizer.

The constant voltage resulting from the rectification of the mains voltage across the capacitor 7 is used to power the photocell and the thyratron 6, and the voltage across the capacitor 5 to power the -tiratron 2.

The device works as follows. The flash of the main lamp is perceived

in this case, the photocell, which thus creates a starting pulse on the grid of the thyratron 2. Lighted, this thyratron discharges capacitor 3. This ends the synchronization phase from the main lamp. Depleted state

the capacitor 3 may be saved for a prolonged period of time (memorized) and indicates that the main lamp has tripped.

In the nearest positive half period

the mains voltage starts charging the capacitor 3 through diode 4 and resistor 5. The charging current and voltage across resistor 5 applied to the grid of the thyratron 6, the network voltage is repeated in the first quarter of the period. When this voltage reaches its maximum, the thyratron 6 is ignited and the synchronization phase from the line voltage is completed. The discharge of the capacitor 7 through the thyratron 6 to the step-up transformer 8 leads to a flash of a pulsed lumina 9. The time interval between flashes of the main and auxiliary lamps is not constant, but always less than the period of change in the mains voltage. The operation of the device is not impaired if the thyratrons are replaced with other elements with similar volt-ampere characteristics (for example, thyristors).

If the plates of the capacitor 3 will close the sync camera, then

the device will synchronize with the network and operate as described above, and the photocell illumination becomes unnecessary.

Subject invention

A device for synchronizing the ignition of a pulsed lamp, containing a source of sync pulses from a flash lamp of direct current, an ignition unit of an additional flash lamp, characterized in that, in order to synchronize the ignition of an additional flash lamp by the maximum voltage of the AC network in the presence of a flash of the main lamp, it is equipped

a capacitor, the plates of which are connected to the anode and cathode of the output thyratron of the source of sync pulses, the anode of the thyratron being connected via a diode to one of the network terminals, and its cathode via a resistor to another network terminal and the grid of the tirathron of the ignition source of the additional pulse lamp.