JPH0277734A - Extending circuit for light emission time of stroboscopic device - Google Patents

Abstract

PURPOSE:To increase the time constant of discharge and to widen the control range of light emission time by providing a voltage supply circuit between the anode of a stroboscopic light emission tube and the ground and connecting a switching circuit in series between a cathode and ground. CONSTITUTION:When a trigger pulse is supplied to the gate G while a voltage is applied between the anode A and cathode K, the stroboscopic light emission tube 12 turns on for a certain time to emit light. The light is emitted for the time determined by the on resistance of the stroboscopic light emission tube 12 and the discharge time constant of a capacitor 15 in the case of the disconnection of a resistance 13. The time constant becomes large when the resistance 13 is connected, so the light emission time can be prolonged and the control range of the stroboscopic light emission time is therefore widened. Further, when the connected resistance is a variable resistance, the range of time base control is variable, a switching circuit of SCR constitution is provided, and its rush current is suppressed to protect the switching circuit.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a circuit for extending flash and flash light emission time.
In particular, the present invention relates to a light emitting time extension circuit using a time constant circuit.

[Conventional technology]

In general, the main use of strobe light emitting tubes is to support illumination in optical cameras, so controlling the strobe light emission time is
Roughly speaking, it was extremely simple, with either full or half-light emission. That is, the strobe light emission time has been controlled by controlling a switching circuit provided between the cathode of the strobe light emitting tube and the ground using an external control signal. Here, the strobe light emission time in the case of no control is determined by the discharge time constant due to the on-resistance between the anode and cathode of the strobe light emitting tube and the capacitance of a capacitor connected in parallel to the power supply. Therefore, the strobe light emission time is controlled within the range of the light emission time determined by this discharge time constant.

[Problem to be solved by the invention]

However, in the case of conventional strobe lights, the light emission time in the case of no control is generally limited to a very short time, so that there are cases where control on the time axis is restricted to some extent. Therefore, depending on the subject, the control of reflected light is not as effective as expected.

[Means to solve the problem]

The present invention; a voltage supply circuit is provided between the anode of the strobe light emitting tube and the ground, and a switching circuit for controlling the light emission time of the strobe light emitting tube is provided between the cathode of the strobe light emitting tube and the ground. connect in series,
A resistor is connected in series to this switching circuit, and a capacitor is connected in parallel to the voltage supply circuit to store charge when the switching circuit is off, and to discharge the stored charge through the strobe light emitting tube and the resistor when the switching circuit is on. It is characterized by being connected to.

[Function] As a result, when the switching circuit is turned on, a resistor is connected in series with the strobe light bulb, so the discharge time constant of the charge stored in the capacitor increases.
It is possible to lengthen the strobe light emission time in the case of no control. Therefore, the control range of strobe light emission time becomes wider.

〔Example〕

The present invention will be described in detail below with reference to Examples.

FIG. 1 is a diagram showing one embodiment of the present invention. The high voltage generating circuit 11 supplies voltage to the strobe light emitting tube 12, and the voltage from the high voltage generating circuit 11 is applied between the anode A of the strobe light emitting tube 12 and the ground GD. That is, a voltage from the high voltage generating circuit 11 is applied to a series circuit of the strobe light emitting tube 12, a resistor 13, and a switching circuit 14, and a voltage is similarly applied to a capacitor 15 connected in parallel with this series circuit.

The switching circuit 14 is a switching element that turns on and off the series circuit by a trigger pulse applied to the switching terminal 18. When the switching circuit 14 is in the on state, the voltage from the high voltage generation circuit 11 is applied to the strobe light emitting tube 12. will be applied. On the other hand, when a trigger pulse is applied to the gate G while a voltage is applied between the anode 8 and the cathode, the strobe light emitting tube 12 becomes conductive for a certain period of time and emits light. The trigger pulse applied to the light emitting terminal 16 is applied to the gate G of the strobe light emitting tube 12 via the trigger circuit 17.

First, when the switching circuit 14 is on and no trigger pulse is applied to the gate G of the strobe light bulb 12, the strobe light bulb is not conducting.
The capacitor 15 is in a state where electricity is stored by the high voltage generating circuit 11.

Now, when a trigger pulse is applied to the light emitting terminal 16, the trigger pulse is applied to the gate G of the strobe light emitting tube 11 via the trigger circuit 17, so that the strobe light emitting tube 11 becomes conductive and emits light.

FIG. 2 shows the characteristics, and shows the characteristics of the light emission level L of the strobe light emitting tube 11 and the time t when a trigger pulse is applied to the gate G of the strobe light emitting tube 11 at time t1. The characteristic curve (■) shows the characteristics when the resistor 13 is not connected, and the characteristic curve (■) shows the characteristics when the resistor 13 is connected.

That is, when the resistor 13 is not connected, as shown in characteristic curve I, at a time T1 determined by the on-resistance of the strobe light bulb 11 and the discharge time constant of the capacitor 15,
The strobe light tube 11 will emit light, but the resistor 13
By connecting , the discharge time constant increases, so as shown in the characteristic curve
It will be longer than 1. That is, light emission continues even at time t2.

Therefore, the control of the luminescence time according to the characteristic curve I is performed at time 1.
The switching circuit 14 is turned off at time T1 from t2 to time t2, but the characteristic curve ■
In the case of , the light emission continues after time t2, so the control range of the light emission time becomes wide, and by appropriately selecting the value of the resistor 13, there is no restriction on control on the time axis. Note that by connecting the resistor 13, the capacitor 15
Needless to say, it is necessary to increase the capacity of the .

〔Effect of the invention〕

As described above, according to the present invention, by connecting a resistor in series with the switching circuit connected in series with the strobe light emitting tube, the strobe light emission time is lengthened and the strobe light emission time is evenly distributed. It becomes possible to control the amount of light.

In addition, if the connected resistor is a variable resistor, the range of time axis control can be made variable, and the switching circuit can be configured as an SCR, and its inrush current (I / d t
It can also serve as a protection for the switching circuit by suppressing the

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a strobe light emission time extension circuit of the present invention, and FIG. 2 is a characteristic diagram showing a characteristic curve of strobe light emission level versus time. 11... High voltage generation circuit, 12... Strobe light emitting tube, 13... Resistor, 14... Switching circuit, 15... Capacitor, 16... Light emitting terminal, 17... Trigger circuit, 18... Switching terminal. Applicant: NEC Corporation Representative

Claims (1)

[Scope of Claims] A voltage supply circuit that supplies a voltage between an anode of a strobe light emitting tube and a ground, and a voltage supply circuit connected in series between a cathode of the strobe light emitting tube and the ground, and a voltage supply circuit that supplies a voltage between an anode of a strobe light emitting tube and a ground, and a voltage supply circuit that supplies a voltage between an anode of a strobe light emitting tube and a ground, and a voltage supply circuit that supplies a voltage between an anode of a strobe light emitting tube and a ground, and a voltage supply circuit that supplies a voltage between an anode of a strobe light emitting tube and a ground, and a voltage supply circuit that supplies a voltage between an anode of the strobe light emitting tube and a ground, and a voltage supply circuit that is connected in series between the cathode of the strobe light emitting tube and the ground, a switching circuit for controlling the switching circuit; a resistor connected in series with the switching circuit; and a resistor connected in parallel with the voltage supply circuit, storing charge when the switching circuit is off, and A strobe light emission time extension circuit comprising a capacitor for discharging stored charge through the strobe light emitting tube and the resistor.