JPS61182276A - Control circuit for luminescent color of two-tone color led package - Google Patents

Abstract

PURPOSE:To control the color development of a two-tone color LED package by fixing the region of forward currents for a monochromatic LED light source, alternately lighting two monochromatic LEDs in a time division manner, determining a color arrangement at the rate of a lighting time and obtaining a neutral color. CONSTITUTION:Pulses P1, P2 having mutually reverse polarity are applied to terminals 3, 4, a resistor R3 is selected, and forward currents sufficient for saturating the brightness of monochromatic LED1, LED2 on the ON of a corresponding transistor Q are flowed. Since the waveforms of pulses P1, P2 having predetermined relationship at that time, the LED1 and the LED2 alternately go ON and OFF, but they are viewed as neutral colors. When the periods T2, T3 of waveforms are changed and the rate of the lighting time of two-tone colors is set, proper neutral colors are acquired. When only one element Q is turned ON and forward currents are flowed through the LED, monochromatic light emission is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light emission color control circuit for a two-color LED package.

(Prior art) Figure 3 shows a circuit for emitting light of three colors (two single colors and an intermediate color) using a conventional two-color LED package, and Figure 4 shows a graph showing the relationship between forward current and brightness of a single-color LED light source. Shown below.

In Fig. 3, 1 is the body of the two-color LED cage, LED 1 and LED 2 are monochrome LED light sources of different colors inside the cage body 1, and R1 and R2 are the monochrome L.
ED light source LED 1, resistor that sets the forward current flowing to LED 2, 2 is a power supply terminal, Ql is monochrome LED light source LE
D1 and Q2 are transistors for passing forward current to the monochromatic LED light source LED 2, and 3 and 4 are their control terminals. Further, A in FIG. 3 is a region where the brightness is unsaturated with respect to the forward current flowing through the monochromatic LED light source LED 1 or the monochromatic LED light source LEI) 2, and B is a region where the brightness is saturated. In the conventional circuit system, when emitting monochrome light, transistor Q1 or transistor Q2 is turned on to flow a forward current to light monochrome LED light source LED 1 or monochrome LED light source LED 2.

When lighting a neutral color, use the transistor Ql.

Turn on both Q2 and turn on the monochrome LED light source LED 1 and LED
2 are lit at the same time, but to obtain a suitable neutral color,
It is necessary to consider the color scheme (brightness ratio) of the two colors, and the forward current flowing through the monochrome LED light source LED 1' + LED 2 can be set individually with the corresponding resistors R1 and R2 to obtain an appropriate intermediate color. It was a circuit method that attempted to realize a color scheme.

(Problems to be Solved by the Invention) However, in the circuit system with the above configuration, the forward current flowing through the monochromatic LED light source LED 1 or LED 2 must be used in region A shown in FIG. ? Slight changes in forward current due to variations in the characteristics of the package body 1 and errors in the resistance values of resistors R1, R2 greatly affect the brightness of a single color, disrupting the color scheme and making it difficult to produce an appropriate neutral color.
, R2, etc. to correct the forward current and adjust the color scheme. Furthermore, as described above, two resistors R1 and R2 are required for one indicator light.

The present invention was made to eliminate such drawbacks, and by fixing the area of the forward current flowing through the monochromatic LED light source, the influence of the above-mentioned variation is eliminated, and the two L
The ED is turned on alternately in a time-divided manner.

It is an object of the present invention to realize a light emitting color control circuit that obtains a stable neutral color at this rate of alternate lighting time without being affected by device characteristics or errors.

(Means for Solving the Problem) The present invention provides a circuit that includes a light emitting diode package having two monochromatic light sources and a resistor that adjusts the brightness of the monochromatic light. The circuit is configured so that the forward current can be obtained by flowing a forward current at a temporal ratio to .

(Function) According to the above-mentioned means, the area of the forward current flowing through the monochrome LED light source is fixed, the two monochrome LEDs are lit alternately in a time-sharing manner, and the color scheme is determined based on the ratio of the lighting time, and an appropriate intermediate color is created. By obtaining this, it is possible to avoid being affected by variations in LED characteristics and errors in resistance, and also to share the forward current setting resistor of one indicator light.

Therefore, the above-mentioned problem can be eliminated.

(Example) FIG. 1 shows an embodiment of a luminescent color control circuit according to the present invention.

In the same figure, R3 is a monochromatic LED light source LED1, L
This is a resistor that sets the forward current flowing through ED2.

Further, PI and P2 in FIG. 2 are repetitive waveforms of the control i9 pulse input to the control terminals 3 and 4 in FIG. 1, and P2 is the polarity of PI inverted. T1 is the period of waveform PI, P2,
T2 is the time during which waveform P1 is at H level within one cycle;
3 is the same time for waveform P2. Here, the resistance value of R3 is set to a value that allows a forward current sufficient to saturate the brightness of the monochromatic LED light source when the corresponding transistor is ON, and the waveform P1 is sent to the control terminal 3, and the waveform P2 is sent to the control terminal 4. When input to the transistors Ql and Q2, the waveform PI.

When P2 is at H level, it is turned on, and in the - period, the monochrome LED light source LED 1 is alternately lit for T2, and the monochrome LED light source LED 2 is lit for T3, but they are not lit at the same time. If T1 is made fast enough for the sensitivity of the human eye,
Although the monochrome LED light sources LED 1 and LED 2 are alternately turned on and off, they appear to be a neutral color to the human eye. A suitable intermediate color is T2. This can be obtained by changing T3 and setting the ratio of the lighting time of the two colors. Further, monochromatic light emission can be obtained by turning on the transistor on the side of the monochromatic LED to be lit and flowing a forward current.

(Effects of the Invention) As described in detail above, in the present invention, when lighting a monochromatic LED light source, a forward current sufficient to saturate the brightness is always passed, so that variations in LED characteristics and errors in the forward current setting resistor are avoided. The change in brightness due to minute changes in the forward current becomes extremely small, and the realization of an appropriate neutral color depends only on the ratio of the pulse width of the repetitive control pulse input to the signal terminal. Therefore, once a control pulse waveform capable of realizing an appropriate neutral color is determined, a stable intermediate color can be obtained without being affected by device characteristics or errors. Also, two single color L at the same time
The forward current setting resistor can be set without turning on the ED light source.
Since it can be shared by two light sources, you only need one. As described above, the present invention has the advantage of reducing the number of parts and eliminating adjustment work when using a large number of three-color indicator lights, and is particularly effective when using a large number of indicator lights.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a control repetitive pulse waveform input to the control terminal of FIG. 1, and FIG.
Color LED; A conventional circuit diagram that emits three colors (two single colors and an intermediate color) in a p-package. FIG. 4 is a graph showing the relationship between forward current and brightness of a single color LED light source. 1... Two-color LED package, 2... Power terminal, 3
...LED 1 lighting control terminal, 4...LED 2
Control terminal for lighting, LED 1, LED 2...Single color LED light source, R3...LED forward current control resistor, Pl.
...Control pulse 1, R2...Control pulse 2, T1
...PL, period of R2, T2...Pi(7)/f pulse width, T3...pulse width of R2, Ql...LED
1 transistor for lighting, Q2...LED 2 transistor for lighting, A...unsaturated area of brightness, B... saturated area of brightness.

Claims (1)

[Claims] A light emitting diode package having two monochromatic light sources;
In a circuit consisting of a resistor that adjusts the brightness of the monochromatic light, a two-color L is characterized in that two monochromatic colors and an intermediate color thereof are obtained by flowing a temporally proportional forward current through a monochromatic light source.
Emission color control circuit for ED package.