Flash works
2015/12/15 view:
Operating Circuit
Normal flash refers to the flash output energy is not adjustable flash, the flash GN nominal flash index is a constant value.
Circuit consists of four parts: Part oscillation boost rectifying the charging section, voltage indication section and pulse trigger flash parts. When the power is turned on, the use of the switching characteristics of a transistor V1, forming an intermittent oscillation, so that T1 primary obtain an alternating voltage, the T1 boost to the secondary to get higher than 300V alternating voltage. After alternating voltage half-wave rectified by the diode D1 into a DC voltage of the main capacitor C2 and C3 charge trigger capacitor energy storage. When the voltage charge to about 70% of rated voltage, indicating circuit neon (Ne) starter indicating the wait state flash in the normal flash. When you press the button AN, trigger circuit (from R3, C3, T2 and Xe composition) generates a pulse voltage is induced in the secondary moment T2 high pressure (approximately 10kV) pulse, by triggering the flash tube Xe Xe flash tube pole inner nitrogen ionization and conduction, electrical energy stored in the capacitor C2 moment by the flash tube discharge into light, to complete a flash.
The camera's built-in flash works above. When there is insufficient brightness of the scene outside the camera's metering system will emit a low-light information, then manually or automatically switched on by the camera flash circuit for charging and flash. Some camera also has an automatic flash amount control system (auto-dimming flash), to obtain a more accurate exposure.
Work Theory
After the flash is fully charged, the flash on the camera sync contacts connected to the flash circuit. During the flash fires, the light emitted from the flash exposure to the subject on the object, reflected from the subject into the camera (exposure) and flash metering element. This metering device will soon transform light energy into an electrical signal input integrating circuit, and then outputs an electrical signal by the integrator circuit with a flash light value proportional; when the flash light value reaches the appropriate amount of exposure to
Canon external flash
Canon external flash
When demand, the output signals of the integrating circuit of the control circuit will trigger a flash stop circuit, so that the flash goes off.
Due to continuous flash flash time is very short, it should be dimmed, the use of flash metering element must be a photosensitive element having a rapid response capacity.
Auto-dimming flash control mode according to their circuit configuration can be divided into two kinds of series and parallel.
In the parallel ends of the main flash tube Xe of a discharge pipe V. Main flash tube ignition operating circuit and the same general type of line. When the main flash light emission amount reaches a certain reference value, by metering device receive, integrating circuit and a control circuit that triggers the main discharge pipe vent control mode has not been immediately discharge energy, so that the main flash tube extinguished.
Parallel automatic dimming flash simple circuit structure, low price, used more often. But each time it will not put the main capacitor finish all the remaining energy discharge finished, so long recharge time, the battery consumption.
Tandem control mode is the semiconductor switching element thyristor rectifier SCR with the main flash in series together, when the light amount of the main flash tube output to achieve the appropriate exposure requirements, the thyristor rectifier SCR automatically cut off the discharge circuit, the main flash tube immediately extinguished, automatic transfer light control.
Advantages tandem control mode is the primary capacitor still holds the remaining energy, which can shorten the recharge time, the battery consumption is also reduced, facilitates rapid chain lightning and recycling. The disadvantage is that the circuit is more complex and costly.
Normal flash refers to the flash output energy is not adjustable flash, the flash GN nominal flash index is a constant value.
Circuit consists of four parts: Part oscillation boost rectifying the charging section, voltage indication section and pulse trigger flash parts. When the power is turned on, the use of the switching characteristics of a transistor V1, forming an intermittent oscillation, so that T1 primary obtain an alternating voltage, the T1 boost to the secondary to get higher than 300V alternating voltage. After alternating voltage half-wave rectified by the diode D1 into a DC voltage of the main capacitor C2 and C3 charge trigger capacitor energy storage. When the voltage charge to about 70% of rated voltage, indicating circuit neon (Ne) starter indicating the wait state flash in the normal flash. When you press the button AN, trigger circuit (from R3, C3, T2 and Xe composition) generates a pulse voltage is induced in the secondary moment T2 high pressure (approximately 10kV) pulse, by triggering the flash tube Xe Xe flash tube pole inner nitrogen ionization and conduction, electrical energy stored in the capacitor C2 moment by the flash tube discharge into light, to complete a flash.
The camera's built-in flash works above. When there is insufficient brightness of the scene outside the camera's metering system will emit a low-light information, then manually or automatically switched on by the camera flash circuit for charging and flash. Some camera also has an automatic flash amount control system (auto-dimming flash), to obtain a more accurate exposure.
Work Theory
After the flash is fully charged, the flash on the camera sync contacts connected to the flash circuit. During the flash fires, the light emitted from the flash exposure to the subject on the object, reflected from the subject into the camera (exposure) and flash metering element. This metering device will soon transform light energy into an electrical signal input integrating circuit, and then outputs an electrical signal by the integrator circuit with a flash light value proportional; when the flash light value reaches the appropriate amount of exposure to
Canon external flash
Canon external flash
When demand, the output signals of the integrating circuit of the control circuit will trigger a flash stop circuit, so that the flash goes off.
Due to continuous flash flash time is very short, it should be dimmed, the use of flash metering element must be a photosensitive element having a rapid response capacity.
Auto-dimming flash control mode according to their circuit configuration can be divided into two kinds of series and parallel.
In the parallel ends of the main flash tube Xe of a discharge pipe V. Main flash tube ignition operating circuit and the same general type of line. When the main flash light emission amount reaches a certain reference value, by metering device receive, integrating circuit and a control circuit that triggers the main discharge pipe vent control mode has not been immediately discharge energy, so that the main flash tube extinguished.
Parallel automatic dimming flash simple circuit structure, low price, used more often. But each time it will not put the main capacitor finish all the remaining energy discharge finished, so long recharge time, the battery consumption.
Tandem control mode is the semiconductor switching element thyristor rectifier SCR with the main flash in series together, when the light amount of the main flash tube output to achieve the appropriate exposure requirements, the thyristor rectifier SCR automatically cut off the discharge circuit, the main flash tube immediately extinguished, automatic transfer light control.
Advantages tandem control mode is the primary capacitor still holds the remaining energy, which can shorten the recharge time, the battery consumption is also reduced, facilitates rapid chain lightning and recycling. The disadvantage is that the circuit is more complex and costly.
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