JPS594476Y2 - Strobe discharge tube device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a strobe discharge tube device, and more specifically to a strobe discharge tube device that can control the voltage of a charging capacitor to always be kept constant.

In the strobe discharge tube capacitor charging circuit, in order to solve problems such as preventing battery consumption, shortening charging time, and obtaining a constant amount of light, after securing a constant charging voltage,
A number of circuits have been proposed to stop or reduce oscillation.

Conventional circuits have a problem in that the amount of light varies due to fluctuations in the charging voltage of the charging capacitor, fluctuations in the power supply voltage of the battery, etc., and fluctuations in the charging voltage due to temperature changes.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and provide a strobe discharge tube device that can be controlled to maintain a constant charging voltage.

In order to achieve the above object, a discharge tube device according to the present invention detects the voltage across a capacitor and operates or deactivates an oscillating transistor according to the detected voltage. One or more diodes are connected to the emitter of the oscillation transistor, Darlington-connected transistors are connected in parallel between the anode of the diode and the base of the oscillation transistor, and the base of the Darlington-connected transistor is at a temperature opposite to that of the diode. The charging circuit was configured to be connected between the voltage dividing resistors of the charging circuit via a constant voltage diode having the characteristics.

With the strobe discharge tube device having the above configuration, extremely reliable and accurate charging power can be obtained.

The present invention will be explained in more detail below with reference to the drawings.

First, high-speed charging will be explained. FIG. 1 is a graph showing charging characteristics of a capacitor charging circuit.

In the figure, A is the charging characteristic of a general charging circuit.

If the set voltage range is the shaded area between VL and Vo, the minimum charging voltage is required to obtain a constant amount of light.

Therefore, the charging time requires t3 in the figure. Generally, charging characteristics are expressed as V=Vo[1-exp(-α1)) (■o: saturation voltage, α: constant), and the rate of voltage increase decreases as the voltage increases, and eventually reaches the saturation voltage V.

reach. vo is determined by the turns ratio of the oscillation transformer.

Therefore, by changing the turns ratio, B in the figure is obtained, and the time to reach ■1 is tl.

Now, if v, = o, s vo, then from the above formula, t3 =
It becomes 1.61xl/α.

If the saturation voltage at B is 2■o, then vt, /Vo=0
．． 4, t1=0.51×1/α is obtained, and if α is also constant, the charging time can be shortened to 1/3 or less.

In reality, there are limits to the power supply capacity and the core capacity of the oscillation transformer, so it does not follow the theory, but as a result of experiments, we obtained a result that is less than 1/2.

However, after time t2, the voltage exceeds the set voltage, making it impossible to obtain a constant amount of light.

Therefore, it is necessary to stop charging when t2 is reached.

The circuit according to the present invention is capable of such charging stop;
Also, the above-mentioned problem has been solved.

FIG. 3 shows a circuit diagram of an embodiment of the present invention.

In the figure, T is an oscillation transformer, Trl is an oscillation transistor, Tr2. Tr3 is an oscillation control transistor, Dz is a constant voltage diode, C1 is an oscillation capacitor, R1 is an oscillation resistor, C2 is a charging capacitor, D2 is a charging current rectifier diode, R2 and R3 are charging voltage setting resistors, Dl
indicates a diode, and E indicates a power source such as a battery.

Ll. L2. L3 indicates each winding of T.

The sum of the base-emitter voltage of Trl and the forward voltage of Dl in the circuit diagram is Vl, Tr2 . The sum of the base-emitter voltage of Tr3 is 2. DZ Zener voltage ■3. The voltage across R3 is assumed to be V4.

In the figure, T, Tri, CI, and R1 constitute an oscillation circuit, which is oscillated by a power supply E.

The voltage induced on the secondary side by the oscillation is rectified by D2 and charged to C2.

The electromotive force induced in L2 by the current in Ll is L2→C1
→ D1 → emitter of Tr□ → base of Trl → current flows through the loop of L2, and oscillation continues.

When the charging voltage gradually increases and v4 reaches a certain value, DZ becomes conductive and Tr2. Turn on Tr3.

When Tr2 becomes conductive, the electromotive force induced in L2 causes a current to flow through the loop of L2→C1→collector of Tr2→emitter of Tr2→L2, and the oscillation transistor Tr1 is turned off, thereby stopping oscillation.

As the oscillation stops, the charging voltage gradually decreases.

■When 4 becomes below a certain value, DZ becomes non-conductive and Tr2
．． Turn off Tr3.

As a result, oscillation begins. After that, repeat the above operation.

(Figure 2 shows a graph of the charging characteristics of the charging circuit according to the present invention.

In the figure, C indicates a charging voltage versus time curve, and C' indicates a power supply current versus time curve during charging.

) Therefore, the charging voltage is kept constant.

The charging voltage is kept constant by turning on and off the oscillation, but the charging voltage that is kept constant is Vl, ■2. V3. ■Determined by 4.

Therefore, in order to keep the charging voltage constant, it is necessary to keep (4) constant.

v4 is ■□, V2. Depends on V3, ■4=■1+■2+
■It becomes 3.

Transistors and diodes generally have temperature characteristics, and the base-emitter voltage of a transistor is 9VBE/9
T2 (mv/℃), forward voltage of diode is 9VF/
9T--2 (mV/'C), the Zener voltage of the Zener diode is 9 vz/9 T=5~20 (mV/'C) (
vz10-25■).

In the circuit according to the embodiment of the present invention, the temperature coefficient of the Zener diode is canceled by the temperature coefficient of the transistor/diode, so that the change in (4) can be minimized.

If necessary, the temperature coefficient can be further adjusted by connecting two Dl in series.

Furthermore, since Tr2 and Tr3 are connected in a Darlington manner, hfe becomes very large, and the oscillation can be controlled by slight fluctuations in (1)4, making it possible to reduce the fluctuation range of the charging voltage.

Since there is a possibility that the voltage v1 between the base of the transistor Tr1 and the anode of the diode D1 varies due to the voltage variation of the battery E, this problem will be considered.

If the current flowing through the diode D1 is IF, the voltage drop VF across the diode D1 is given by the following equation.

VF=kT/q-1nC(IF+IS)/IS, 1
``ikT/q・Stone (IF/IS)...■'','
IF>>15 (IS is saturation current) (k: Boltzmann constant, T: absolute temperature, q: electron charge) Since the emitter current of transistor Tr1 is equal to the above IF, the base-emitter voltage VBE of transistor Tr1 is It is given by the following formula.

VBE=kT/q・stone [(IF+IS)/IS, 1″
=kT/Q-1n(IF/15)---■■■ From the formula, δVBE/δIF-δvF/δ■F kT/q・(1/IF) = 1/39・(1/IF)・...■ Voltage V between the anode of diode D1 and transistor T11 when the current flowing through transistor Tr1 changes by △IF
The change in Δ■1 is given by the following formula.

△■1 = (δVBE/δIF + δVF/δIF) △IF = 2・(1/39)・(1/IF) When △IFIF changes from 1A to 2A, △■1 becomes △■2/ 39 # 1/20 = about 0.05 V, so even if the power supply voltage fluctuates, the corresponding voltage ■
It can be seen that the fluctuation of 1 is negligible.

Therefore, fluctuations in charging voltage can also be suppressed to a very small value.

As mentioned above, the fluctuation width of the charging voltage can be reduced, and the charging voltage can be made smaller in response to fluctuations in the power supply voltage of batteries, etc., and temperature changes, so the strobe discharge tube device according to the present invention can be used stably and reliably. A constant amount of light can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a graph showing the charging characteristics of the capacitor charging circuit, Fig. 2 is a graph showing the charging characteristics of the charging circuit according to the present invention, and Fig. 3 is a circuit diagram showing an embodiment of the strobe discharge tube device according to the present invention. . T...Oscillation transformer, Trl...Oscillation transistor, Tr2. Tr3: oscillation control transistor, DZ: constant voltage diode, C
1... Oscillation capacitor, R1...
Oscillation resistor, C2...Charging capacitor, D2.
...Charging current rectifier diode, R2, R3...
...Charging voltage setting resistor, Dl...Diode, E...Battery, LL, L2. L3...
...Each winding of the transformer.

Claims (1)

[Scope of utility model registration request] In a strobe discharge tube device that detects the voltage across a capacitor and activates or deactivates an oscillation transistor depending on the detected voltage, one or more diodes are connected to the emitter of the oscillation transistor in the DC-DC converter, and the Darlington-connected transistors are connected in parallel between the anode of the diode and the base of the oscillation transistor, and the base of the Darlington-connected transistor is connected to the voltage dividing resistor of the charging circuit via a constant voltage diode having a temperature characteristic opposite to that of the diode. A strobe discharge tube device characterized in that the strobe discharge tube device is connected between.