JPS598318Y2 - automatic flashing device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic flashing device that detects the brightness and darkness of the surroundings and automatically flashes a lighting lamp.

Conventionally, this type of automatic flashing device is as shown in Figure 1, in which the AC power supply is connected to a diode D1 and a capacitor C.
The DC voltage obtained by rectification and smoothing is applied to the Zener diode Z via the resistor R9, and this Zener voltage, that is, the stabilized DC voltage (2).

is applied to both ends of resistors R2 and R3 connected in series, and a reference voltage (2) obtained by dividing the voltage by both resistors is applied to the emitter, and at the same time, a stabilized DC voltage (2) is applied to the emitter.

A light/dark detection transistor Q1 is applied to its base with a divided voltage (■) obtained by dividing the voltage by a photoelectric conversion element P such as CdS or a phototransistor and an operating point adjustment resistor R1.
The collector output of the triac T is connected to the SCR (S
) is applied to the base of the controlling transistor Q2, and the lighting lamp L is made to blink by the triax T, and the base of the light/dark detection transistor Q1 and the collector of the SCR control transistor Q2 are connected by a feedback resistor R4. Was.

The operation of the conventional example will be explained below.

When the surroundings become dark, the resistance of the photoelectric conversion element P increases, and the divided voltage ■1 applied to the base of the light/dark detection transistor Q1 decreases, and this divided voltage ■1 becomes the reference voltage ■2.
In other words, when the ambient brightness falls below a certain level, the light/dark detection transistor Q0 becomes conductive, and the base current flows to the SCR control transistor Q2, so the SCR control transistor Q2 also becomes conductive. Then, SCR(S) is fired.

This SCR(S) is the lead. When passed through, the AC power supply AC. The trigger current of the triac T flows through the illuminating lamp L and the rectifier circuit D, and the triac T becomes conductive, so that the illuminating lamp L lights up.

Next, when the surroundings become brighter, the resistance of the charging conversion element P decreases, so that the divided voltage ■1 applied to the base of the light/dark detection transistor Ql increases, and this divided voltage ■1 becomes the reference voltage ■ When it becomes 2 or more, the light/dark detection transistor Q1 is reverse biased and cut off, and the SCR control transistor Q2 is also cut off.

Therefore, the SCR(S) and the triac T are not turned on, and the illumination lamp L is turned off.

By the way, the base of the light/dark detection transistor Q1 and the SCR
Since the collector of the control transistor Q2 is connected to the feedback resistor R4, charging conversion occurs when the surroundings become dark and the resistance of the photoelectric conversion element P increases, the light/dark detection transistor Q1 becomes conductive, and the lighting lamp L lights up. The resistance value RA of the element P is different from the resistance value RB when the surroundings become bright and the illumination lamp L is turned on, and the blinking operation of the illumination lamp L depending on the brightness of the surroundings has a so-called hysteresis characteristic.

In this case, the resistance RA of the photoelectric conversion element P when turned on and the resistance R8 of the photoelectric conversion element P when turned off satisfy the following relationship.

However, VBE is the voltage drop between the emitters of the light/dark detection transistor Q1, and VCE is the SCR control transistor Q.
The collector-emitter voltage VR6 of No. 2 is the voltage across the resistor R6.

? Second, since R4>R5 or R6, by changing the feedback resistor R4 or the resistor R, the hysteresis width, that is, the ambient brightness when the illuminating lamp L is turned on and the ambient brightness when the illuminating lamp L is turned off, can be changed. It is now possible to change the difference between

When adjusting the hysteresis characteristic in such a conventional example, the lighting point and the turning-off point are changed by changing either of the resistors Rl and R4, so the turning-on point is adjusted and then the turning-off point is adjusted. Therefore, if the feedback resistor R4 is changed, the lighting point will also change accordingly, and when adjusting the hysteresis characteristic, the resistors Rl and R4 must be adjusted many times, making the adjustment work troublesome. It had the disadvantage of being

The present invention aims to solve the above-mentioned drawbacks.

Examples will be described below using figures.

FIG. 2 shows an embodiment of the present invention, in which the DC power applied to the control circuit of the lighting lamp blinking triac T is applied to the Zener diode Z through the resistor R9, and the Zener voltage of the Zener diode Z is increased. In other words, stabilized DC voltage■.

A reference voltage (2) obtained by dividing the voltage by two resistors R2 and R3 connected in series is applied to the emitter, and a divided voltage is obtained by dividing the stabilized DC voltage Vc by the resistor R1 and the photoelectric conversion element P. ■The collector output of the light/dark detection transistor Q1, with voltage 1 applied to the base, is applied to the base of the SCR control transistor Q2, and the collector output of the SCR control transistor Q2 is applied to the gate of the SCR (S) that controls the triac T. A series circuit including a feedback resistor R4 and a reverse current element diode D4 is inserted between the base of the light/dark detection transistor Q1 and the collector of the SCR control transistor Q2.

In the figure, R5 to R13 are resistors, and C1 and C2 are capacitors.

Furthermore, the stabilized DC voltage stabilized by the Zener diode Z is applied only to the light/dark detection transistor Q1, which requires a small current, and is not stabilized to the SCR control transistor Q2 through which the SCR (S) trigger current flows. However, in order to stabilize the operating characteristics, a stabilized DC voltage is applied only to the light/dark detection transistor Q1.
.

It is sufficient to apply the SCR control transistor Q
Even if the DC voltage applied to 2 changes, the timing of blinking does not change.

The operation of the present invention will be explained below.

Now, the basic blinking operation of the lighting lamp L by the automatic blinking device according to the present invention has a hysteresis characteristic, just like the conventional example, but in the present invention, the reverse current is connected in series with the feedback resistor R4. Since the blocking diode D4 is connected, the following relationship is satisfied at the time of operation.

However, ■D4 is the forward voltage of the reverse current blocking diode D4.

As is clear from the above equation, the lighting point of the illumination lamp can be adjusted only by adjusting the resistor R1, regardless of the feedback resistor R4, and the lighting point can be changed when setting the light-off point as in the conventional example. This makes it easy to adjust the hysteresis characteristics.

In other words, the diode D4 is reverse biased when the SCR control transistor Q2 is off, and the feedback resistor R
By preventing current from flowing through R4, the feedback resistor R4 does not affect the lighting, thereby making it easy to adjust the hysteresis characteristic.

Therefore, in the embodiment, the desired hysteresis characteristic can be obtained by first adjusting the resistor R1 to adjust the lighting point, and then adjusting the resistor R4 to adjust the turning-off point. There is no need to repeatedly readjust the point when the light is turned on and the point when the light is turned off.

The present invention is constructed as described above, and in an automatic flashing device having hysteresis characteristics similar to the conventional example, a backflow blocking diode is connected in series with a feedback resistor, and an SCR
When the control transistor is off, the diode is reverse biased to prevent current from flowing through the feedback resistor, and when the lighting lamp is turned on, the feedback resistor is not affected at all, and only the operating point setting resistor R1 is adjusted. Unlike the conventional example, the turning on point does not change when setting the turning off point, so unlike the conventional example, the hysteresis characteristic can be adjusted by repeatedly adjusting the turning on point and the turning off point. There is no need for adjustment, and the adjustment work of the hysteresis characteristic can be easily performed.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a conventional example, and FIG. 2 is a circuit diagram of an embodiment of the present invention. L is a lighting lamp, T is a switching element, Z is a Zener diode, R1 to R13 are resistors, P is a photoelectric conversion element, Q1,
Q2 is a transistor, (S) is an SCR, and D4 is a diode.

Claims (1)

[Scope of utility model registration request] The collector output of the light/dark detection transistor is connected to the collector output of the light/dark detection transistor, which has a reference voltage applied to its emitter and a divided voltage obtained by dividing the DC power supply by a resistor for adjusting the operating time and a charge conversion element and applied to its base. applied to the base of
The collector output of the SCR control transistor is applied to the base of the light/dark detection transistor via a feedback resistor, and the SCR control transistor is used to drive the SCR that controls the switching element for lighting blinking, thereby producing an automatic blinking device. An automatic flashing device in which a reverse current blocking diode is connected in series with the feedback resistor, and when the SCR control transistor is turned off, the diode is reverse biased to prevent current from flowing through the feedback resistor.