CN2059785U

CN2059785U - Inverse excited electronic flash lamp

Info

Publication number: CN2059785U
Application number: CN 88203340
Authority: CN
Inventors: 韩明武
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-02-11
Filing date: 1988-02-11
Publication date: 1990-07-25

Abstract

The utility model relates to an electronic flash lamp circuit for a camera. The utility model is formed according to the inverse excitation type switching power supply theory. The electronic flash lamp circuit for a camera is suitable for the electronic flash lamps of various cameras, but the cameras must use the battery as the energy source. Compared with the present domestic and foreign electronic flash lamp circuits, the charge efficiency can be improved by more than two times, and the charge time can be shorten by one third. The electronic flash lamp circuit for a camera solve the problems of high failure rate of the transistors and the voltage increasing transformers of the present domestic and foreign electronic flash lamp circuits. The electronic flash lamp circuit for camera is provided with an automatic power-off circuit and a flash index regulation circuit. The circuit cost of the utility model is basically identical to the circuit cost of the present flash lamp circuit.

Description

Inverse excited electronic flash lamp

The utility model relates to a kind of novel camera flash tube.

What the capacitor charging circuit of existing domestic and international electronic flash circuit for lamp adopted in principle basically is the positive activation type switching power circuit, and its weak point is:

1, charge efficiency is lower: the step-up transformer of this kind circuit is output as constant voltage output, be generally about 350 volts, and the voltage of capacitor will by zero or very low value be charged to about 250 volts of rated voltages always, the difference of the voltage between them all consumes on the coil resistance of step-up transformer high pressure winding, difference heals when big, the power that consumes is bigger, makes the former end electric current of transformer bigger, and the power consumption of pliotron is also bigger; Circuit needs tens of exciting curents to hundreds of milliamperes in order to keeping the work of step-up transformer, and after charging process finished, this electric current existed; When cell voltage was reduced to certain numerical value, the induced potential of step-up transformer output was lower than the rated voltage of electric capacity, and electric capacity fills less than rated value voltage, and the electric energy in the battery is not fully utilized.Therefore, the gross efficiency of present flash tube electric capacity charging both domestic and external is all lower.

2, the failure rate during circuit working is higher: when capacitance voltage is low, because the output voltage of step-up transformer and the difference of capacitance voltage are excessive, make the electric current in the high pressure winding excessive, the electric current of former end winding also scales up, easily cause step-up transformer and pliotron the overload and damage, these two kinds of faults often occur in flash lamp circuit and come to a startup and the photoflash lamp running hours, are modal faults in the flash lamp circuit.

3, when capacitance voltage during near rated voltage, because the reducing of pressure reduction between the induced potential of step-up transformer high pressure winding and the main capacitance voltage, the charging voltage curve enters the flat region, and voltage rises slow, and especially when cell voltage reduced, this influence was more obvious.

4, step-up transformer high pressure umber of turn is higher, is generally 1300 circle to 1500 circles, and line is through thinner, thereby makes the technique for coiling complexity of step-up transformer.In addition, pliotron is generally the high β pipe of multiplication factor more than 300, and the replacing and the selection of triode in maintenance and the production are greatly limited.

The purpose of this utility model is under the constant substantially situation of circuit cost, a kind of circuit that can overcome or improve existing domestic and international flash lamp circuit weak point is provided, its capacitor charging circuit is used the inverse-excitation type switch power-supply principle, and current conversion efficient is improved greatly.The course of work of circuit is as follows: during work, and the energized K switch, positive source is through R ₂, N ₃, T ₂, T ₁Emitter junction produce an electric current to power cathode, through T ₂, T ₁The amplification of pipe is at N ₁In have an electric current to flow through.This electric current is at N ₃Middle induction one voltage is through T ₂, T ₁Emitter junction, D ₂, R ₃Produce a positive feedback current, make T ₁Rapidly saturated and N ₁In linear in time increase of electric current, at T ₁Between the period of saturation, because diode D ₁Connection make N ₂Middle no current flows through.Because W ₂, T ₂N is worked as in the restriction of the current amplifier of forming ₁In electric current when reaching its maximum Is, N ₃In induced voltage reverse, through R ₃, C ₃, T ₁, T ₂Emitter junction makes T ₂T ₁Be in reverse bias and shutoff rapidly.By changing road law, N ₁, N ₂Have one with (1/N+1) I in the series coil of forming _SFor the electric current of initial value by power supply E through D ₁To capacitor C ₁Charging, wherein N is N ₂The number of turn and N ₁The ratio of the number of turn.During pressure drop on not considering diode and coil resistance, its induced potential and capacitor C ₁Terminal voltage equate.When this electric current linearity drops to zero, N ₃Reverse voltage disappear, circuit enters next cycle of oscillation.N ₁In maximum current Is do not become with the size of capacitance voltage, capacitance voltage is higher, the time that transistor ends is shorter, N ₁The duty ratio of middle current waveform is bigger, N ₁In average current just big, thereby the speed that charges into electric energy is faster.Regulate W ₂Can obtain different Is, thereby obtain different charging rates.When capacitance voltage reaches rated voltage, the neon tube Ne build-up of luminance of voltage indication usefulness, the neon tube electric current flows through T ₃Base stage makes T rapidly ₃Guarantee adequate food and, T ₁, T ₂Pipe ends.The circuit failure of oscillations, the complete machine electric current is very little, in this example less than 1 milliampere.When photoflash lamp flash of light back or capacitance voltage drop to certain value, Ne is extinguished, T ₃Pipe ends, T ₁T ₂Work again, make capacitance voltage be charged to rated voltage automatically.Regulate W ₁Can obtain different capacitance voltage rated values.Main points of the present utility model are in capacitor charging circuit to use the inverse-excitation type switch power-supply principle and by R ₁, W ₁, Ne and T ₃Form autostop and guide number regulating circuit.The utlity model has following advantage:

1, charge efficiency height: N ₁N ₂The induced electromotive force of series coil keeps equating with load voltage at any time, therefore step-up transformer high pressure output potential is under the situation of not considering factors such as diode drop, coil resistance, at any time keep being complementary, overcome step-up transformer and the big deficiency of pliotron loss that existing flash lamp circuit constant voltage output is brought thus with capacitance voltage; Reverse excitation circuit does not need tens of extremely hundreds of milliamperes the exciting curents as the forward converter; The electromotive force of this patent circuit high pressure winding output is irrelevant with the reduction of supply voltage in theory, and therefore when supply voltage was reduced to 2.5 volts by specified 6 volts, circuit still can be charged to capacitance voltage 300 volts; This patent circuit power electric current is less, and when maximum in this example only 620 milliamperes, and adopted effective automatic stop arrangement, thereby the utilance of battery improves greatly; This circuit has adopted N ₁N ₂Tandem-type connection, promptly saved coil, when transistor was ended, source current was not by transistor, directly pass through N ₁N ₂To the electric capacity charging, further improved efficient.By experimental data, when the power supply virtual voltage is 5 volts, capacitance 200 microfarads, source current is about 500 milliamperes, and capacitance voltage rises to 250 volts by 50 volts, only took time 3.5 seconds, and at present general flashing light is under the situation of same supply voltage, generally more than 1 peace, the charging interval is wanted 6 to 8 seconds to charging current.Charge efficiency can improve more than 2 times.General four joint No. 5 common batteries (300 MAH) but group flashing light more than 250 times under these conditions.And the longest charging interval is only about 20 seconds.

2, reduced the failure rate of flash lamp circuit: because raising, the power supply input current maximum of efficient have reduced over half, the burden of pliotron is alleviated greatly, the loss of transformer also reduces greatly, has solved modal two kinds of faults in the present flash lamp circuit effectively.

3, further improved charging rate: this circuit power input current raises with capacitance voltage to be increased, and charging rate is accelerated.This routine result, when source current only is a half of present photoflash lamp electric current, the charging interval can improve more than 1/3rd.Regulate W ₂Can obtain the different charging intervals.

4, can adapt to the requirement of various different rated voltages: the rated value of the capacitance voltage of this circuit is said in theory and can be reached infinitely great, only is subjected to the withstand voltage influence of circuit element.Therefore, this circuit can be charged to 350 volts of following arbitrary magnitudes of voltage under the situation that does not change any parameter of circuit, and this just provides possibility for the making of varying index photoflash lamp.

5, step-up transformer high pressure umber of turn about 300 circles, only is 1/4th to 1/5th of a present photoflash lamp step-up transformer only seldom, and technique for coiling is simple.In addition, power transistor is the pliotron of common multiplication factor in this example, thereby price is low, and range of choice is wide.Therefore though circuit of the present invention has been used switching diode of two common triodes more, a semifixed resistor, resistance totally 5 elements, and circuit assembly this is roughly the same with present flash lamp circuit.

Accompanying drawing is an inverse-excitation type flash tube circuit embodiments schematic diagram.

B adopts existing general photoflash lamp step-up transformer magnetic core, N among the figure ₁=45 circles, N ₂=315 circles, N ₃=45 circles; T ₁Select general VCEO 〉=40V for use, ICM 〉=1.5A person gets final product.All the other T ₂T ₃Be General N PN type triode, D ₂Be general switching tube, D ₁Model be 1N4007, in this example of power supply with four the joint No.5 cells.

Residual voltage after the initial value of capacitance voltage is the general photoflash lamp flash of light of 50V(on the electric capacity is 50V), when reducing to different value, record several groups of different capacitance C at cell voltage (voltage during load), different electric capacity rated voltage V ₀The time charging interval T several groups of parameters changing with the decline of supply voltage.

When E was 6V, source current was adjusted to 550 to 620 milliamperes, recorded one group of data such as table 1.

When cell voltage dropped to 5V, this moment, source current was 450 to 550 milliamperes, recorded data such as table 2.

When voltage dropped to 4V, this moment, electric current was 380 to 400 milliamperes, recorded data such as table 3.

When voltage dropped to 3V, this moment, electric current was 250 to 300 milliamperes, recorded data such as table 4.

When cell voltage was reduced to 2.5V, electric current was 180 to 250 milliamperes, records data such as table 5.

Claims

1, an employing is by the main element transistor T ₁, step-up transformer B, rectifier diode D ₁That form is C ₁The camera photoflash lamp of the reverse excitation circuit of charging usefulness is characterized in that:

A, N ₂, D ₁, C ₁In the series circuit of forming, N ₂Same D ₁An anodal joining end and N ₁Same T ₁The joining end of collector electrode is an end of the same name;

B.N ₂The other end and N ₁Linking more arbitrarily in 3 at the two ends of winding, power cathode.

2,, it is characterized in that utilizing by Ne, R according to the described device of claim 1 ₁, W ₁The charge indicator of forming is with an end and the W of Ne ₁Centre slice link the other end and T ₃Base stage link T ₃The collector electrode of pipe, emitter respectively with T ₂, T ₁Base stage, the emitter of the multiple tube of forming link, when making the Ne conducting, and T ₃Saturated T ₁End.