JP2510087Y2 - Lighting control circuit for two-color light emitting diode element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a lighting control circuit for a two-color light emitting diode element including a pair of light emitting diodes having different emission colors.

[Outline of device]

The present invention relates to a lighting control circuit for a two-color light emitting diode element, which is composed of a pair of light emitting diodes having different light emission colors, and outputs two-phase pulses having the same frequency from a two-phase pulse generation supply and a phase difference longer than each pulse width. By supplying a pair of on / off switches to each pair of light emitting diodes to supply the pair of light emitting diodes to each other, the pair of light emitting diodes can be operated without damage due to heat generation of the light emitting diode, deterioration of characteristics, and shortening of life. The LEDs emit light at the same time with brightness so as to exhibit a mixed emission color of both emission colors of a pair of light emitting diodes.

[Conventional technology]

Conventionally, a two-color light emitting diode element composed of a pair of light emitting diodes having different light emitting colors is commercially available. Then, by selecting either one of the pair of light emitting diodes of this light emitting diode element and passing a direct current of a constant level or passing a pulse current through the light emitting diode, the two-color light emitting diodes are made to emit light of different colors. I was trying to light it.

[Problems to be solved by the invention]

By the way, if a pair of light emitting diodes of such a two-color light emitting diode element are made to emit light at the same time, the emitted light color will be a mixed color of the respective emission colors, so that this two-color light emitting diode element is used in an electronic device. When it is adopted as a display device, it is very convenient because one of the pair of light emitting diodes can display four modes, that is, both are in a light emitting state and both are in a light emitting state.

However, in order to make a pair of light emitting diodes emit light at the same time, if both are energized at the same time, the heat generated by this is approximately double that in the case where only one is energized. If the same current as that for emitting light is applied, the two-color light emitting diode element may be damaged, its characteristics may be deteriorated, and its life may be shortened. Therefore, in order to avoid these problems, when both the light emitting diodes are made to emit light at the same time, a smaller amount of current has to be passed than when only one of them is made to emit light. However, by doing so, it cannot be denied that the light emission brightness of both light emitting diodes is inevitably reduced.

In view of this point, the present invention allows a pair of light emitting diodes to emit light with high brightness at the same time without causing damage due to heat generation of the light emitting diodes, deterioration of characteristics, and shortening of life. It is intended to propose a lighting control circuit for a two-color light emitting diode element exhibiting mixed emission colors.

[Means for solving problems]

A lighting control circuit of a two-color light emitting diode device according to the present invention comprises a pair of light emitting diodes (2) and (3) having different emission colors from each other.
The lighting control circuit includes a two-phase pulse generator (4) for generating two-phase pulses having the same frequency and a phase difference longer than each pulse width, and a pair of on / off switches SWa and SWb. The two-phase pulse from the pulse generator (4) is supplied to the pair of light emitting diodes (2) and (3) through the pair of on / off switches SWa and SWb separately, and the pair of on / off switches SWa and SWb. Depending on whether the pair of light emitting diodes (2), (3) is in a light emitting state, both are in a light emitting state, and both are in a non-lighting state, a pair of light emitting diodes (2), (3) ) Is controlled by lighting.

[Operation] According to the present invention, a pair of on / off switches SW
When a and SWb are turned on at the same time, a pair of light emitting diodes (2) and (3) are supplied with a two-phase pulse having the same frequency from the two-phase pulse generator (4) and a phase difference longer than each pulse width. Both light emitting diodes emit light at the same time,
Since they are not energized at the same time, a pair of light emitting diodes can simultaneously emit light with high brightness without being damaged by heat generation of the light emitting diodes, deterioration of characteristics, and shortening of life.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to FIG. (1) shows a two-color light emitting diode element,
This is made up of light emitting diodes (2) and (3) whose emission colors are different from each other, for example, the emission colors are red and green, and they are housed in a common package (not shown). In the light emitting diodes (2) and (3), for example, the respective cathodes are connected to each other, and the common terminal Tc is derived from this, and the terminals Ta and Tb are derived from the respective anodes.

(4) is a two-phase pulse generator, both output terminals (4
From a) and (4b), a phase difference that is the same in frequency and longer than each pulse width (here it is the same pulse width, but it may be slightly different), here a phase shift of 1/2 of the period. Two-phase pulses Pa and Pb (see FIGS. 2A and 2B) are generated. The two-phase pulse generator (4) can be composed of a pulse generator and a 180-degree phase shifter.

Both output terminals (4a) of this two-phase pulse generator (4),
(4b) is connected to terminals Ta and Tb of the two-color light emitting diode element (1) through on / off switches SWa and SWb and current limiting resistors Ra and Rb, respectively. The terminal Tc is grounded.

The pulse current peak value applied to the pair of light emitting diodes (2) and (3) is the same as the rated current peak value when one of them is made to emit light even when both are made to emit light at the same time. Further, the frequencies of the two-phase pulses Pa and Pb generated from the two-phase pulse generator (4) are selected to be sufficiently high so that the light emitting diode can continuously emit light due to the afterimage effect of the eyes.

Next, the operation of this control circuit will be described. Switch SW
When both a and SWb are off, both light emitting diodes (2) and (3) naturally do not emit light. When only the switch SWa is turned on, the light emitting diode (2) emits red light. When only the switch SWb is turned on, the light emitting diode (3)
Emits green light. When both the switches SWa and SWb are turned on, both the light emitting diodes (2) and (3) emit light, and the emission color thereof becomes orange which is a mixed color of red and green.

[Effect of device]

According to the present invention described above, a pair of light emitting diodes emit light at the same time with high brightness without causing damage due to heat generation of the light emitting diodes, deterioration of characteristics, and shortening of life. It is possible to obtain a lighting control circuit for a two-color light emitting diode element capable of exhibiting mixed emission colors. In the present invention, in particular, 2
Since the two-phase pulses from the phase pulse generator have the same frequency and have a phase difference longer than each pulse width, current flows through the pair of light emitting diodes at the same time when the pair of on / off switches are both turned on. Since there is no such thing, damage due to heat generation of the light emitting diode, characteristic deterioration, shortening of life is sure, and by controlling the phase difference of each two-phase pulse and each pulse width, each light emission color of a pair of light emitting diodes can be controlled. It is possible to adjust the hue of mixed colors.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a time chart used for the explanation. (1) is a two-color light emitting diode element, (2) and (3) are light emitting diodes, and (4) is a two-phase pulse generator.

Claims (1)

(57) [Scope of utility model registration request] 1. A lighting control circuit for a two-color light-emitting diode element comprising a pair of light-emitting diodes having different emission colors, and a two-phase pulse generating a two-phase pulse having a phase difference longer than each pulse width at the same frequency. A generator and a pair of on / off switches, wherein the two-phase pulse from the two-phase pulse generator is supplied to the pair of light emitting diodes through the pair of on / off switches separately. Depending on the on / off of the pair of on / off switches, one of the pair of light emitting diodes is in a light emitting state, both are in a light emitting state and both are in a light-off state, and the pair of light emitting diodes are controlled to be turned on. A lighting control circuit for a two-color light emitting diode element.