Flash is a flash device for indicating changes in the direction of vehicle travel. Flasher new circuit design, a low voltage switch circuit, a high voltage switch circuit, pulse generating circuit, two-pole circuit amplifying an output and two sets of double-tube light indication circuit. Which is mounted in the cartridge body flash, through its control can accurately indicate the direction of vehicle travel, especially protective effect includes an automatic play characteristics, and can automatically stop the flasher lamp circuit operates in short-circuit failure occurs, the driver through the flasher with a visual indication of the failure of the flasher working conditions, can be found at any time and troubleshooting. Common flasher capacitive type, flap-type transistor and type categories.
1, the working principle
First, the basic operation common type flash circuit
refers to a common type of flash energy of flash output flash is not adjustable, i.e. the nominal flash flash index GN is a constant value.
circuit consists of four parts: an oscillation boosting part, a rectifying charging section, and a pulse voltage indication section flash trigger portion.
When the power is turned on by the switching characteristics of the transistor V1, the formation of an intermittent oscillation, to obtain the primary an alternating voltage of T1, T1 boosted by so obtained secondary alternating voltage of greater than 300V. After the alternating voltage half-wave rectified by the diode D1 becomes a DC voltage of the main capacitor C3 is charged trigger capacitor C2 and the energy storage. When the charged voltage to about 70 percentage of the rated voltage, the indication circuit neon (Ne) starter, in the normal flash flash indicating a wait state. When the button is pressed AN, trigger circuit (manufactured by R3, C3, T2 and Xe composition) generates a pulse voltage, an instantaneous high voltage (about 10kV) pulses induced in the secondary of T2, by triggering the flash tube Xe Xe flash tube inner pole nitrogen ionization and conduction, the electrical energy stored on capacitor C2 instantaneous discharge tube into light by a flash, a flash is completed.
works
in the camera’s built-in flash above. When the external scene brightness is insufficient, the camera metering system will be issued as a low information, this time manually or automatically switched on by the camera and the flash charging the flash circuit. The camera also has some selfControlling the amount of flash dynamic system (auto flash light), to obtain a more accurate exposure.
Second, the principle of automatic dimming flash
after the flash is fully charged, the camera flash sync contact connected to the flash circuit. During flash light, the flash light emitted from the subject irradiated on an object, reflected back from the subject enters the camera (exposure), and the flash metering element. This metering element will soon light energy into an electrical signal input of the integrator circuit, and then output an electric signal by the integrator circuit is proportional to the magnitude of flash light; when the flash light value reaches a suitable amount of the exposure, the integrating circuit it outputs an electrical signal control circuit stops a flash trigger circuit, so that the flash goes off.
Since the flash duration flash time is very short, it should be dimmed, the flash metering member is a photosensitive member used must have a fast response capability. Automatic control of the flash light control circuit according to their different structure, can be divided into two kinds of parallel and series. In parallel with both ends of the flash tube Xe, a main drain pipe V. The flash ignition operation of the circuit of the main pipe line and the same general type. When the amount of the main flash emission reaches a certain reference
value, receiving, integrating circuit and the control circuit is triggered by metering member bleed tube main control mode has not been immediately bleed bleed energy, the main flash off tube.
parallel circuit configuration of the automatic dimming flash simple, low cost, many applications. But each time it will not completely discharge the main capacitor residual energy bleed all finished, the recharge time is long, a large battery consumption.
series of control is the semiconductor switching element thyristor rectifier SCR and the main flash in series together, when the light amount of the main flash tube output reaches a proper exposure required, the thyristor rectifier SCR automatically cut off the discharge circuit, the main flashtube immediately extinguished, automatic dimming control. Advantage of the tandem control mode in the main capacitor remaining energy is still preserved, it is possible to shorten the time of recharging, the battery consumption is reduced accordingly, it facilitates rapid chain lightning and recycling. The disadvantage is that the circuit is more complex, costly.
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