JPS6081878A - Emitting light color controlling method of composite light emitting diode - Google Patents

Abstract

PURPOSE:To enable to vary emitting light color of high speed by applying the electric inputs of junctions of composite light emitting diodes at the time division ratio of the maximum allowable input current time product of the diodes, thereby controlling the mixture ratio of the emitting light amounts of different wavelengths. CONSTITUTION:Composite LEDs 1 have three junctions J1, J2, J3 for emitting red, green and blue, and are operated to emit lights via drive input pulse currents ip1, ip2, ip3. In the relationship represented by the maximum input power P per unit time allowable at the continuous light emitting time, P=(IP<2>TP)NR, the maximum input current IP and the maximum input pulse width TP are preset. However, N indicates the number of pulses repeated during the unit time T, and R indicates a proportional constant, and a symbol in ( ) represents the current time product. The apparent emitting light colors of the composite LEDs 1 vary by the ratio of the input pulse widths t1, t2, t3 (TP=t1+t2+t3) time-divided from the input pulse currents ip1, ip2, ip3.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for controlling the color of emitted light of a composite light emitting diode, and more particularly, a method for controlling the color of emitted light of a composite light emitting diode, in particular, controlling the electrical input of each junction of the composite light emitting diode at a time division ratio of the maximum allowable input current of the diode. The present invention relates to a method for controlling the color of emitted light that enables efficient mixed color development.

In general, in order to change the apparent color of light emitted by using multiple light emitting diodes (hereinafter referred to as LEDs) with different emission wavelengths, for example, one LED emits red light and the other LED emits green light.
When D is used, both LEDs are closely combined, the amount of light emitted by each LED is controlled, and the mixing ratio of the amounts of light emitted by both colors is changed to obtain an intermediate color from red to green.

Conventionally, as a method of controlling such mixed color development, for example, a method of controlling based on a circuit diagram shown in principle in FIG. 4 is known. That is, in this case, for example, 0 LEDs emitting red and green light 11. 12 is connected in parallel with the power supply battery 13, and variable resistors 14, 15 are connected to the parallel circuit, respectively, and the magnitude of the current flowing through the LED II, 12 is controlled by the variable resistors 14, . Adjust each LED by 15
The amount of emitted light is controlled, and the controlled red light and green light are mixed to obtain an appropriate intermediate color from red to green.

In this light emission control method, as long as the current flowing through each LED is less than the allowable value for the diode junction, the current can be varied over a wide range to create any neutral color. This can be called a light emission control method. However, in this case, heat loss due to circuit resistance is large, the efficiency is low, and it is not suitable for dynamic lighting.

On the other hand, for composite LEDs in which a single light emitting element has multiple junctions with different emission wavelengths, it is common to control light emission using a dual maximum current limited type emission control method. In this case, not only the maximum allowable current of the can joint is determined due to the structure of the joint, but also the maximum allowable value of the total input power of each joint is determined. Therefore, in order to dynamically control light emission while maintaining the maximum amount of light emission within these constraints, there is a drawback that extremely troublesome and complicated circuits must be used.

In view of the above-mentioned drawbacks, the present invention aims to provide a method for controlling the color of emitted light of a composite LED, which is extremely simple and can also change the color of emitted light at high speed. The mixing ratio of the amount of light emitted at different wavelengths is controlled by applying the electrical input to the can junction of a composite light emitting diode having a junction at a time division ratio of the maximum allowable input current of the diode. The present invention provides a method for controlling the color of emitted light from a composite light emitting diode.

Hereinafter, the present invention will be described in more detail with reference to the drawings.
FIG. 3 is a waveform diagram showing an example of the mutual relationship of drive pulse currents for LEDs according to the method of the present invention. In Figure 1, 1
is a composite type LED, in this case three junctions J1. J2. J3, and are connected to each other in a circuit so as to be operated to emit light by a driving human power pulse current ip+ Pipt+ 'pa. In order to drive the composite LED 1 according to the method of the present invention,
Each joint J1. J2. The current is applied to J by repeated pulse-like energization as follows. In other words, if P is the maximum input power per unit time allowed during continuous energization and light emission for the entire composite LEDI, then P = (Ip
'rp) ・N, R maximum input pulse width Tp is determined in advance. However, N is the number of pulses repeated in unit time T, R is a proportionality constant, and the value in parentheses represents the current selection. Therefore, the joint J1 of the composite LED1. J2. Incoming caval current ip1'''p21ip3 flowing through each of J3
As shown in FIG. 2, the maximum input current ■p is constant, and each time-divided input pulse width is set to 1. , 12
．． 13. Here, the pulse width t1
+ t2y t3 are three junctions J with different emission wavelengths,
, J2. It is determined in accordance with the ratio of the amount of light emitted by each J3, and the apparent color of the emitted light of the composite LEDI changes depending on this ratio. However, each pulse width is restricted by the relationship T p =t t + t 2 +ts.

FIG. 3 is a schematic block diagram showing an example of a drive circuit for a display panel in which a large number of the above-mentioned composite LEDs 1 are arranged in a lattice pattern. A macrocomputer 4 outputs color information according to a predetermined program, and 4 is a display panel in which a large number of composite LEDs 1 are arranged in a lattice pattern and are lit and displayed in response to output signals from the computer 3.

In this way, if the serial color information C is sequentially input to, for example, an 8-digit shift register 2 according to the synchronization signal S, and the 8-digit output signal IC is input to the microcomputer 3, then, according to a preset program, for example, 16 It outputs 16 parallel color information signals R, G, and B of red, green, and blue, respectively. Therefore, on the display panel 4, in this case, each of the 256 composite LEDIs arranged vertically and horizontally, 16 in total, is as follows:
The lighting is often controlled and colored as appropriate.

In this case, the number of LEDs 1 arranged, the arrangement form, the addition or reduction of the combinations of light emitting diodes such as adding a colorless LED to make the white color more vivid, etc. can be set as appropriate.

As described above, according to the emitted light color control method according to the present invention,
Since the color development of the double photodiode is controlled by time-division energization of pulsed current to each junction, color tone control can be performed freely over a wide range without any power loss, and the total light output is can be easily done by changing the peak value of the applied pulse, and since the maximum input is limited in advance by the sum of the pulse widths (Tp) that energize each junction, there is no risk of damaging the LED due to excessive input. In addition to the fact that there is no color difference, it also has features such as being able to change the color tone at high speed.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram showing the connection relationship of a composite light emitting diode, Fig. 2 is a waveform diagram showing an example of the mutual relationship of drive pulse currents according to the method of the present invention for the multiplication factor diode from Fig. 1, and Fig. 3 is a Composite light emitting diode...Composite light emitting diode, Jl, J2. J3...Junction 1, Tp
...Maximum input current, t1+t2+F t8...Time-divided input pulse width, aim 1...
...Maximum input pulse width. (7) Figure 1 Figure 2

Claims (1)

[Claims] By applying the electrical input to each junction of a composite light emitting diode having a plurality of junctions with different emission wavelengths at a time division ratio of the maximum allowable input current of the diode, the amount of light emitted at different wavelengths can be reduced. A method for controlling the color of emitted light from a composite light emitting diode in which the mixing ratio is controlled.