JPS6214637Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lamp lighting control device that turns on the lamp at the same time as a switch operation when the lamp is turned on, and gradually dims the light and turns off the lamp after the switch operation when the lamp is turned off.

Conventionally, this type of lamp lighting control device has a configuration as shown in Fig. 1, where LP is a lamp, TR ₁ is a transistor for lamp lighting,
TR ₂ and TR ₃ are transistors for controlling transistor TR ₁ , SW is a switch for lighting the lamp,
_R1 to _R5 are resistors, _C1 is a capacitor, and B is a power supply terminal.

In the circuit shown in FIG. 1, when the switch SW is closed, the transistor TR ₃ is OFF, the transistor TR ₂ is OFF, and the transistor TR ₁ is OFF, so that the lamp LP is not lit.

When the switch SW is opened from closed, the resistances R ₅ and R ₃
The base current flows through the transistor TR ₃ .
The transistor TR ₂ is turned on as the base current flows through the resistors R ₂ and R ₄ , and the transistor TR ₂ is turned on as the base current flows through the resistor R ₁ , turning on the lamp LP. At this time, capacitor _C1 is charged through resistor _R4 .

Then, when the switch SW is turned from open to closed, transistor TR ₃ is turned off, but the base current flowing through resistor R ₂ flows into capacitor C ₁ , lowering the potential difference between both ends of capacitor C ₁ , and increasing the potential difference. By becoming smaller, the base current decreases. Therefore, even after the transistor TR ₃ is turned off, the transistor TR ₂ remains in the saturation region and is completely turned on while the base current flowing through the resistor R ₂ is large. However, as the base current continues to decrease, the transistor TR ₂ enters the unsaturated region, and the current flowing through resistor R ₁ also begins to decrease. When the base current flowing through the resistor R ₁ decreases further, the transistor TR ₁ also enters the unsaturated region and the lamp LP begins to dim.
Eventually, no current flows through the resistor _R2 , turning off the transistor _TR2 , and no current flows through the resistor _R1 , turning off the transistor _TR1 as well.

That is, in this conventional circuit, the transistor
After TR ₃ turns OFF, the lamp LP remains fully ON until transistor TR ₂ enters the unsaturated region and then transistor TR ₁ enters the unsaturated region. R ₁ , R ₂ ,
The expansion and contraction occur due to variations in R ₄ , capacitor C ₁ , transistors TR ₁ and TR ₂ and changes due to temperature, resulting in a feeling of discomfort to the operator.

The present invention solves these conventional drawbacks, and the lamp lighting control device according to the present invention will be described below with reference to FIGS. 2 and 3.

Fig. 2 shows a lamp lighting control device according to an embodiment of the present invention. In Fig. 2, LP is a lamp, TR ₁ is a lamp lighting transistor connected in series with this lamp LP, and SW is a lamp lighting transistor. The switch B is a power supply terminal, which is the same as that shown in FIG.

_R6 to _R8 are resistors, _C2 is a capacitor, _TR4 is a transistor as a voltage-driven amplifier element, _D1 is a constant voltage element, and _D2 is a diode.
One end of the switch SW is connected to the power supply terminal B via a resistor _R8 , and the other end is grounded. One end of the lamp LP is connected to the power supply terminal B, and the other end is grounded via a transistor _{TR1 .}
The base of the transistor TR4 is connected to a power supply terminal B through a series circuit consisting of a resistor _R6 , a transistor _TR4 , and a constant voltage element _D1 , and the input terminal of the transistor _TR4 is connected to a resistor
The input terminal is grounded via _R7 , and is connected to the intermediate point between the lamp LP and transistor _TR1 via a capacitor _C2 . Furthermore, the anode side of a diode _D2 , the cathode side of which is connected to the input terminal, is connected to the intermediate connection point between the resistor _R8 and switch SW.

In the circuit shown in Fig. 2, when the switch SW is closed, the gate of the transistor TR ₄ is grounded through the resistor R ₇ , the transistor TR ₄ is OFF, the base current of the transistor TR ₁ does not flow, and the transistor TR ₁
is also OFF, and the lamp LP does not light up.

When the switch SW is changed from closed to open, a voltage determined by resistors R ₇ and R ₈ is applied to the gate of transistor TR ₄ , transistor TR ₄ is turned on, and resistor R ₆ , transistor TR ₄ , constant voltage element D ₁ and Base current flows, transistor TR ₁ turns on, and lamp LP lights up.

At this time, capacitor C ₂ is instantly charged through resistor R ₈ .

Here, the resistance R ₈ has a sufficiently smaller value than the resistance R ₇ .

Also, when the switch SW is turned from open to close, the resistance
The voltage supplied to the gate of transistor TR ₄ via R ₈ is cut off, and discharge begins with a relatively fast time constant determined by capacitor C ₂ and resistor R ₇ , and the gate voltage quickly drops, causing transistor TR ₄ enters the unsaturated region from the saturated region. into the unsaturated region,
When the base current of the transistor TR ₁ decreases and the transistor TR ₁ also enters the unsaturated region, the lamp LP begins to dim, and at the same time the collector voltage of the transistor TR ₁ rises and increases through the capacitor C ₂ to the gate of the transistor TR ₄ . is subjected to negative feedback, slowing down the rate of dimming. That is, after the switch SW is operated, the dimming starts at a fast speed without negative feedback, bringing the transistor _TR1 into the unsaturated region, but after the dimming starts, the dimming occurs at a very slow speed due to negative feedback.
Therefore, the time it takes to enter the unsaturated region can be ignored, and the light begins to dim immediately after the switch is operated.

Figure 3 shows a comparison of the voltage at point a in the circuit of Figure 1 and the voltage at point b in the circuit of Figure 2, that is, changes in the collector voltage of transistor _TR1 , where the horizontal axis is time and the vertical axis is is the collector voltage of transistor TR ₁ , which is O when it is completely lit and V _B when it is completely off.
voltage.

In other words, when the switch SW is turned from open to closed at t ₀ , in the conventional circuit, the fully lit state continues until t ₁ as shown by curve a, and dimming starts from t ₁ . In the circuit, as shown in curve b, dimming starts at the same time as the switch SW is operated.

As described above, according to the lamp lighting control device of the present invention, it is possible to eliminate the sense of discomfort when operating the switch, and the period of full lighting that remains after operating the switch.
It is possible to solve the problems of component variations between t ₀ and t ₁ and expansion and contraction due to the influence of temperature, and the number of components does not increase, but rather the capacitance can be reduced due to the effect of negative feedback. Effects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional lamp lighting control device, Fig. 2 is a circuit diagram showing a lamp lighting control device according to an embodiment of the present invention, and Fig. 3 is a circuit diagram showing a conventional lamp lighting control device and a lamp of the present invention. It is a characteristic diagram which compares and shows the characteristic at the time of dimming of a lighting control device. LP...Lamp, TR ₁ , TR ₄ ...Transistor,
D ₁ ... constant voltage element, R ₆ , R ₇ , R ₈ ... resistance, C ₂ ...
...Capacitor, SW...Switch, B...Power supply terminal.

Claims (1)

[Scope of utility model registration request] The other end of a switch whose one end is connected to a power supply terminal via a first resistor is grounded, and the other end of a lamp whose one end is connected to the power supply terminal is grounded via a transistor, and the base of the transistor is connected to a second connected to the power supply terminal via a series circuit consisting of a resistor, a voltage-driven amplification element, and a constant voltage element,
The input terminal of the voltage-driven amplification element is grounded via a third resistor, the diode is connected to the intermediate connection point between the lamp and the transistor via a capacitor, and the cathode side is connected to the input terminal. A lamp lighting control device in which an anode side is connected to an intermediate connection point between the first resistor and the switch.