KR20150071974A - Circuit for driving light emitting diode - Google Patents

Abstract

The present invention relates to a light emitting diode (LED) driving circuit, and more specifically, to an LED driving circuit capable of driving LEDs efficiently. According to the present invention, the LED driving circuit includes: a light emitting unit including multiple LEDs separated in one or more groups; an MCU which outputs a synchronized driving signal for each of the groups; a logic circuit which outputs a modulation signal for each of the groups from the MCU except for the overlapping areas; and a control circuit which uses the modulation signal output from the logic circuit and outputs the modulation driving signal.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a light emitting diode driving circuit, and more particularly, to a light emitting diode driving circuit capable of efficiently driving a light emitting diode.

Recently, light emitting diodes (LEDs) having advantages such as efficiency, color diversity, and design autonomy have been attracting attention as a light source of illumination .

A light emitting diode is a semiconductor device which emits light when a voltage is applied in a forward direction, has a long lifetime, low power consumption, and has electrical, optical, and physical characteristics suitable for mass production.

In order to effectively use such a light emitting diode as a light source of illumination, a driving system capable of driving with a commercial AC power supply is required.

A single color LED can be used to drive an LED used in a lighting device, but an LED that emits light of a different color to the LED can be driven together to improve the light quality or to add an additional function that changes the color of the light .

In addition, white light can be realized by using LEDs emitting red, green, and blue corresponding to the three primary colors of light.

In order to drive the LEDs emitting different colors, the LEDs can be divided into groups and driven, and a PWM (Pulse Width Modulation) driving method can be used.

SUMMARY OF THE INVENTION An object of the present invention is to provide a light emitting diode driving circuit which can be implemented with high efficiency without limitation of a maximum duty value in a PWM control type control circuit that can be used in a lighting device of a light emitting diode.

According to an aspect of the present invention, there is provided a light emitting device comprising: a light emitting unit including a plurality of light emitting diodes divided into at least one group; An MCU for outputting synchronized driving signals for the respective groups; A logic circuit for outputting a modulated signal excluding an overlapping portion of the drive signal outputted for each group from the MCU; And a control circuit for outputting a modulated driving signal by using the modulated signal output from the logic circuit.

Here, the control circuit may output a continuous modulation drive signal in which signals for driving the groups are successively connected.

In addition, the modulation drive signal may be a signal in which the signals for driving the groups are successively connected without overlapping with respect to time.

Here, the logic circuit may include an XOR gate.

Here, the light emitting unit may include a first group that emits light of a first color, a second group that emits light of a second color, and a third group that emits light of a third color.

The logic circuit may include: a first XOR gate for operating the first group of driving signals and the second group of driving signals; And a second XOR gate for calculating the driving signals of the second group and the driving signals of the third group.

Also, the first color may be red, the second color may be green, and the third color may be blue.

Here, the MCU may output a synchronized driving signal with the same period for each group.

The present invention has the following effects.

In the non-cyclic continuous PWM drive method, there is no limitation of the maximum duty value, and the output capability of the drive circuit can be utilized to the maximum. However, since this control method is an acyclic PWM method, a high-specification MCU is required. Therefore, it may be difficult to apply to an illumination using an LED.

However, the present invention can provide a driving circuit capable of controlling an illumination device using an aperiodic PWM signal using a low-specification MCU.

Therefore, the output capability of the driving circuit can be utilized to the maximum, and a low-specification driving circuit can be implemented without any limitation of the duty value in the entire section.

In the MCU, a periodic synchronous PWM signal having the same period is generated, so that it can be implemented using a low-specification MCU. In addition, it is possible to generate an aperiodic continuous PWM signal by using this periodic synchronized PWM signal without using a complicated algorithm.

1 is a block diagram showing an example of a light emitting diode driving circuit.
2 is a signal flow diagram illustrating a primary PWM signal generated in an MCU.
3 is a schematic diagram showing a detailed configuration of a logic circuit.
4 is a signal flow diagram showing the final drive signal.
5 is a signal flow diagram showing a periodically fixed sequential PWM signal.
6 is a signal flow diagram showing an aperiodic continuous PWM signal.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

1 is a block diagram showing an example of a light-emitting diode driving circuit.

As shown in FIG. 1, the light emitting diode driving circuit includes a light emitting unit 40 including a plurality of light emitting diodes divided into at least one group.

The MCU 10 is configured to output a synchronized drive signal for each group of the light emitting units 40.

A logic circuit 20 for outputting a modulated signal excluding the overlapping portion of the drive signals output from the MCU 10 to each group of the light emitting units 40 is included.

Then, the control circuit 30 can output the modulated driving signal by using the modulated signal outputted from the logic circuit 20.

The light emitting unit 40 may include a first group that emits light of a first color, a second group that emits light of a second color, and a third group that emits light of a third color. Here, a group for emitting light of different colors may be included, or another group for emitting light of at least one of the first to third colors may be included.

Here, as an example, light of the first color may be red light, light of the second color may be green light, and light of the third color may be blue light. That is, the light emitting unit 40 may include a first group for emitting red light, a second group for emitting green light, and a third group of light emitting diodes (LED) for emitting blue light.

Further, each group may include one or a plurality of LEDs.

In such an example, the three colors may be mixed with one another and used as illumination to emit white light. However, the present invention is not limited thereto, and various groups and LEDs of various colors may be used.

Hereinafter, the first group of the light emitting unit 40 emits red light, the second group emits green light, and the third group emits blue light.

A switching element (not shown) may be connected to the light emitting unit 40 so that each of the light emitting units 40 may be driven sequentially or at least partially. Hereinafter, the detailed configuration of the light emitting unit 40 will be omitted.

The MCU 10 can output a synchronized driving signal with the same period for each group of the light emitting units 40. [

That is, as shown in Fig. 2, the synchronized PWM drive signals (1, 2, 3) can be outputted with the same period.

These three PWM driving signals 1, 2, and 3 may be signals driving the first group, the second group, and the third group, respectively.

The pulse widths of the PWM driving signals 1, 2 and 3 may be different from the predetermined brightness of each group of the light emitting units 40. For example, the pulse width of the first group can be determined according to the predetermined brightness, but the pulse width corresponding to the portion where the second and third groups do not intersect with each other can be proportional to the brightness. This operation can be performed by the logic circuit 20 and the control circuit 30, which will be described later.

The drive signal output from the MCU 10 is input to the logic circuit 20. [ The logic circuit 20 may include XOR gates 21 and 22 as shown in Fig.

The XOR gates 21 and 22 may act on signals for driving the first group, the second group, and the third group, respectively, to generate a driving signal of the desired light emitting unit 40. [

As an example, the driving signal 1 of FIG. 2 can be directly used as a red light emission signal R for driving the first group of light emitting units 40 for red light emission.

On the other hand, the driving signal 1 of the first group and the driving signal 2 of the second group are calculated in the first XOR gate 21 to form a signal G for green light emission. That is, a signal excluding the overlapping portion of the drive signal 1 and the drive signal 2 is formed.

In addition, the driving signal 2 of the second group and the driving signal 3 of the third group are calculated by the second XOR gate 22 to form a signal B for blue light emission. That is, a signal excluding the overlapping portion of the drive signal 2 and the drive signal 3 is formed.

Thus, the driving signal does not have a portion where the red light emission signal R, the green light emission signal G, and the blue light emission signal B overlap. In addition, a continuous signal without a pause is formed between these signals.

Accordingly, a final driving signal as shown in FIG. 4 is formed, and the control circuit 30 drives the light emitting unit 40 by the driving signal thus formed.

In this manner, a continuous PWM signal of an irregular system is finally formed, and the light emitting unit 40 can be efficiently driven through these signals.

Since the MCU 20 generates the periodically synchronized PWM signal having the same period, it can be implemented using a low-specification MCU. In addition, it is possible to generate an aperiodic continuous PWM signal by using this periodic synchronized PWM signal without using a complicated algorithm.

Usually, one of the time division methods for PWM division uses signals as shown in Fig. In other words, the period is fixed for each channel (group), and the duty value is varied and controlled. This circuit can be implemented with a simple and low-specification MUC, but the maximum duty value is limited to 1/3 of the whole section, and the output capability of the driving circuit may be so limited.

In the non-cyclic continuous mode as shown in FIG. 6, the maximum duty value is not limited and the output capability of the driving circuit can be utilized to the maximum. However, since this control method is an acyclic PWM method, a high-specification MCU is required. Therefore, it may be difficult to apply to an illumination using an LED.

However, as described above, the present invention can provide a driving circuit capable of controlling the lighting apparatus using the non-periodic PWM signal using the low-specification MCU 10.

Therefore, the output capability of the driving circuit can be utilized to the maximum, and a low-specification driving circuit can be implemented without any limitation of the duty value in the entire section.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

10: MCU 20: logic circuit
21: first XOR gate 22: second XOR gate
30: control circuit 40:

Claims (8)

A light emitting unit including a plurality of light emitting diodes divided into at least one group;
An MCU for outputting synchronized driving signals for the respective groups;
A logic circuit for outputting a modulated signal excluding an overlapping portion of the drive signal outputted for each group from the MCU; And
And a control circuit for outputting the modulated driving signal by using the modulated signal output from the logic circuit. The light emitting diode drive circuit according to claim 1, wherein the control circuit outputs a continuous modulation drive signal in which signals for driving the groups are successively connected. The light-emitting diode drive circuit according to claim 1, wherein the modulation drive signal is a signal in which the signals for driving the groups are successively connected to each other without overlapping with time. The light-emitting diode drive circuit according to claim 1, wherein the logic circuit includes an XOR gate. The light emitting device of claim 1, wherein the light emitting unit includes a first group that emits light of a first color, a second group that emits light of a second color, and a third group that emits light of a third color To the light emitting diode driving circuit. 6. The semiconductor memory device according to claim 5,
A first XOR gate for operating the first group of driving signals and the second group of driving signals; And
And a second XOR gate for calculating the driving signals of the second group and the driving signals of the third group. The light emitting diode driving circuit according to claim 5, wherein the first color is red, the second color is green, and the third color is blue. The light emitting diode driving circuit according to claim 1, wherein the MCU outputs a synchronized driving signal having the same period for each of the groups.

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