JPS62216436A - Light emitting diode lighting device - Google Patents

Abstract

PURPOSE:To take out always a current from a power source to make the supply current constant by using a collector open type transistor-transistor logic integrated circuit which is connected in parallel to a light emitting diode and permits the supply current to pass through for extinction of the light emitting diode and stops the current for the control of lighting of the light emitting diode. CONSTITUTION:A collector open type transistor-transistor logic integrated circuit 13 is operated as a switching element and has always the contact closed and is connected in parallel to a light emitting diode 11 in this state. At this time, the circuit 13 permits the supply current to pass through resistances 12 and 14, and the light emitting diode 11 is not lit. When a control signal is given to the circuit 13, the contact is opened, and the voltage applied to the light emitting diode rises to give a lighting voltage, and the supply current flows through the resistance 12 and the light emitting diode 11. If values of resistances 12 and 14 are selected in accordance with characteristics of the circuit 13 and the light emitting diode, the value of the current flowing to the resistance 12 is kept at a small change independently of lighting/extinction of the light emitting diode, and the variance of the supply current is prevented.

Description

[Detailed Description of the Invention] [Summary] In a light-emitting diode lighting device using a transistor-transistor logic integrated circuit, the light-emitting diode is connected in parallel to the light-emitting diode, and a power supply current passes through when the light-emitting diode is turned off, and the current is stopped when controlling the light-emitting diode to turn on. This is a light emitting diode lighting device that uses an open-collector type transistor logic integrated circuit to constantly draw current from a power source to keep the power source current constant.

[Industrial application field]

The present invention relates to improvements in light emitting diode lighting devices.

The light emitting diode starts emitting light when the applied forward voltage exceeds the dark value. In order to maintain stable light emission without changing the light emission conditions, it is desirable to have a light emitting diode lighting device that is equipped with a stable power supply that can supply the required current and that does not cause fluctuations in the power supply voltage.

[Conventional technology]

Conventionally, a light emitting diode lighting device as shown in the circuit diagram of FIG. 3 has been used. In the figure, l is a light emitting diode, 2 is a resistor, and 3 is an open-collector transistor logic integrated circuit. Normally the circuit 3 is switched off.

However, when an input signal is applied, the switch is turned on, and voltage is supplied from the power supply Vcc to the light emitting diode 1 via the resistor 2, and the light emitting diode lights up. Uchichi light-emitting diodes draw current from the power supply when lighting, but do not draw current when clearing.

[Problem that the invention seeks to solve]

In the conventional device described above, when a large number of light emitting diodes are used, when these multiple light emitting diodes are turned on or off at the same time, the power supply load changes significantly, causing fluctuations in the power supply current. Enlarge. Therefore, there is a risk that other circuit parts included in the integrated circuit will be adversely affected and malfunction of the circuit will occur.

[Means for solving problems]

As shown in the principle diagram of the present invention in FIG. The light emitting diode lighting device of the present invention is equipped with a resistor 14 connected to a transistor-transistor logic integrated circuit 13 of the type, and the resistance values of the resistors 12 and 14 are selected so that the value of the current flowing through the series resistor 12 is small. Solved by the device.

[Effect]

In the device of the present invention, the open collector transistor logic integrated circuit 13 operates as a switching element and is connected in parallel to the light emitting diode 11 with its contacts always closed.

At this time, the circuit 13 passes the power supply current through the resistors 12 and 14, and the light emitting diode 11 is not turned on.

When a control signal is applied to the circuit 13, the contacts are opened and the voltage applied to the light emitting diode is increased to provide a lighting voltage.

This time, the power supply current flows through the resistor 12 and the light emitting diode 11.

By selecting the values of the resistors 12 and 14 according to the characteristics of the circuit 13 and the light emitting diode, the value of the current flowing through the resistor 12 can be maintained at a small change regardless of whether the light emitting diode is turned on or off, preventing fluctuations in the power supply current. You can.

〔Example〕

The present invention will be described in detail according to the illustrated embodiments.

FIG. 2 shows a circuit diagram of the light emitting diode lighting device of the present invention. 21 is a light emitting diode, 22 and 24 are resistors, and 23 is an open collector transistor logic integrated circuit.

During normal operation, when the light emitting diode 21 is not lit, a high level signal is applied to the input section of the logic integrated circuit 23. At this time, the output section of the logic integrated circuit 23 becomes low level, and current flows from the power supply Vcc through the resistors 22 and 24.

When it is desired to light up the light emitting diode, a low level signal is applied to the input section of the circuit 23, and the output of the circuit 23 is set to a high level. Inflow current from power supply Vcc is stopped;
The voltage drop across the resistor 22 is reduced, and a voltage that lights up the light emitting diode is supplied from the power source Vcc to the light emitting diode 21.

Resistors 22 and 24 required to turn on and off the light emitting diode
can be defined as follows.

When the light emitting diode is lit, R1 = (Vcc - VLED ON) / I LE
D ON light emitting diode quenching, FLED 0FF = (Vcc - (VLED ON - ΔV) ) /R
1vt, 0+ I LED OFF -R2= VL
ED ON-Δ■Here, VLED ON: Terminal voltage when the light emitting diode is lit,
I LED OS: Current when lighting the light emitting diode, V
LO: Low level output voltage of circuit 23, ILHD OF
F: Current of the circuit 23 during light emitting diode clarification, ΔV: 0.5v to 1. It is Ov.

〔Effect of the invention〕

According to the present invention, the value of the current-current fluctuation during lighting and clearing of the light emitting diode can be reduced to within one-tenth of the conventional value, and the effect is extremely large.

[Brief explanation of drawings]

FIG. 1 is a principle diagram of the present invention, FIG. 2 is a circuit diagram of a light emitting diode lighting device according to an embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional light emitting diode lighting device. In the figure, 1.11.21 is a light emitting diode, 2.12.14.22.24 is a resistor, 3.13.23 is an open collector transistor logic integrated circuit, and VCC is a power supply. Figure 1 Figure 2

Claims (1)

[Claims] A light emitting diode (
11), the series resistor (12), and the light emitting diode (1
A resistor (1) whose connection point with 1) is connected to an open-collector transistor logic integrated circuit (13).
4), and both resistance values are selected so that the current value of the series resistor (12) becomes a constant value when the light emitting diode is turned off and turned on.