KR20190025582A - Driving apparatus for light emitting and controlling method thereof - Google Patents

Abstract

The present invention relates to a driving device for a light emitting diode which can accurately express a desired color by adjusting inputted color coordinate values in accordance with inputted brightness values, and to a control method thereof. Provided are the driving device for a light emitting diode comprising a control part for receiving a brightness value and a color coordinate value of the light emitting diode to be controlled and adjusting the color coordinate value in accordance with the received brightness value to control the driving of the light emitting diode, and a driving unit for driving the light emitting diode under the control of the control part; and the control method of the driving device.

Description

TECHNICAL FIELD [0001] The present invention relates to a light emitting diode driving apparatus,

The present invention relates to a light emitting diode driving apparatus and a control method thereof for controlling color illumination according to input color coordinate values and brightness values.

Recently, interest and demand for light emitting diode (LED) illumination are increasing.

Such a light emitting diode light can be manufactured in a compact manner, so that it can be used in a place where it is difficult to install with conventional light, and it is possible to implement various colors and easily adjust the lightness, thereby being used as system light suitable for movie watching, reading, meeting and the like.

In addition, the power consumption is 1/8 of incandescent lamp, and the lifetime is 5 ~ 10 times of 5 ~ 100,000 hours, and it is environment friendly and various designs are possible with mercury-free light source.

Due to these characteristics, LED lighting business is being promoted as a national project in many countries including Korea, USA, Japan and Australia.

Conventional lighting has been used merely for the purpose of emitting light or informing some important information. However, as living standards have increased, driving devices having more complicated and various functions have been developed for convenience and desire of people have. Since the light emitting diode has a very high color reproduction rate and can control the color temperature and the luminance in detail, the lighting control system using the light emitting diode can satisfy the convenience and the equipment of these people.

Such a light emitting diode driving system can be configured as shown in FIG.

Referring to FIG. 1, a general LED driving system includes a control server and a control panel connected to each other through a TCP / IP system to perform lighting on / off control, dimming control, and power monitoring function. And a remote controller for controlling are connected by an illumination communication protocol.

In the driving system of the general LED as described above, CIE 1931 chart is often used for color control, and three color light emitting diodes of red, green and blue are used to express various colors. By using such a tri-color light emitting diode, it is possible to express various colors by appropriately combining the erecting ratios of the three color light emitting diodes.

However, in practice, the color coordinates of the light emitting diode are shifted due to the influences of the current and the temperature, and the color of the desired illumination is slightly changed according to the brightness of the illumination.

 Conventionally, a feedback system or a sensing circuit has been added to overcome such a problem, but this causes another problem of circuit area and manufacturing cost.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a light emitting diode driving apparatus and a control method thereof that can accurately express a desired color by adjusting input color coordinate values according to input brightness values.

According to one aspect of the present invention, there is provided a method of driving a light emitting diode, including: controlling a light emitting diode driving by adjusting a color coordinate value according to a brightness value of a light emitting diode to be controlled; And

A driving unit for driving the light emitting diode under the control of the control unit;

And a driving circuit for driving the light emitting diode.

According to one technical aspect of the present invention,

A first driver for driving a red light emitting diode under the control of the controller;

A second driver for driving a green light emitting diode under the control of the controller; And

And a third driver for driving a blue light emitting diode under the control of the controller.

According to one technical aspect of the present invention, the control unit includes a look-up table having a color coordinate value set according to a brightness value, and adjusts the input color coordinate value according to a received brightness value.

According to one technical aspect of the present invention, the look-

A red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, and a blue light emitting diode, .

According to one technical aspect of the present invention, when the input brightness value is equal to or greater than a predetermined reference brightness value, the x-coordinate value of the red light emitting diode increases and the y-coordinate value of the red light emitting diode decreases Diode driver.

According to one technical aspect of the present invention, when the input brightness value is equal to or greater than a preset reference brightness value, the x-coordinate value of the green LED is decreased and the y-coordinate value of the green LED is increased Diode driver.

According to one technical aspect of the present invention, when the input brightness value is equal to or greater than a preset reference brightness value, the x-coordinate value of the blue light emitting diode increases and the y-coordinate value of the blue light emitting diode decreases Diode driver.

According to another aspect of the present invention, there is provided a method of controlling the brightness of a red light emitting diode, a green light emitting diode, and a blue light emitting diode by receiving a brightness value and a color coordinate value of a light emitting diode to be controlled, Determining;

Selecting x color coordinate values and y color coordinate values of the red light emitting diode, the green light emitting diode, and the blue light emitting diode from a preset lookup table according to brightness values of the red light emitting diode, the green light emitting diode, and the blue light emitting diode; And

Determining a ratio of the brightness values of the red light emitting diode, the green light emitting diode, and the blue light emitting diode according to the x-coordinate values and the y-coordinate values of the selected red light emitting diode, the green light emitting diode, and the blue light emitting diode,

And a control method of the light emitting diode driving apparatus.

According to the present invention, there is an effect that a desired color can be accurately expressed by adjusting an input color coordinate value according to an inputted brightness value.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a general LED driving system; FIG.
2 is a graph in which a color coordinate moves according to a current.
3 is a schematic configuration diagram of a light-emitting diode drive device of the present invention.
4 is an embodiment of a look-up table used in the LED driving apparatus of the present invention.
5 is a flow chart showing a control method of the LED driving apparatus of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, in order that those skilled in the art can easily carry out the present invention.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

The same or similar reference numerals are used throughout the drawings for portions having similar functions and functions.

In addition, in the entire specification, when a part is referred to as being 'connected' with another part, it is not only a case where it is directly connected, but also a case where it is indirectly connected with another element in between do.

Also, to include an element means to include other elements, not to exclude other elements unless specifically stated otherwise.

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

The color coordinate system of the color control used to control the color of the LED is an XYZ coordinate system, which is referred to as a CIE 1931 XYZ coordinate system, and X, Y, and Z are tristimulus values. It has characteristics similar to the human light recognition algorithm that recognizes red, green, and blue colors as fundamental values. The X, Y, Z coordinates can be matched with the CIE 1931 chromaticity diagram xyY through Equation 1 as follows.

(Equation 1)

Here, xi, yi, and zi denote chromaticity values.

Equation 1 can be changed as shown in Equation 2 using xi + yi + zi = 1 again.

(Equation 2)

Equation (2) can obtain an almost accurate color mixing formula by using a four-ary operation in mixing colors by a formula for a color mixing process.

Assuming that the light source is n, when n light sources are mixed, it can be expressed as the following Equation 3.

(Equation 3)

The result of Equation (3) can be transformed into the CIE 1931 chromaticity diagram xyY value using Equation (2), and the following Equation (4) can show the result.

(Equation 4)

If the Ymixed luminous intensity is set to 1 lm and the mixing ratios of Y1, Y2, and Y3 to the respective red light emitting diodes, green light emitting diodes, and blue light emitting diodes with respect to 1 m are set using the results of Equation 4, As shown in Fig.

(Equation 5)

XR, yR, xG, yG, xB, and yB are x-coordinate values and y-coordinate values of the red light emitting diode, x-color coordinate values of the green light emitting diode, and y- And lmR, lmG and lmB denote the mixing ratios of the red light emitting diode, the green light emitting diode and the blue light emitting diode with respect to the illumination output of 1 m, respectively, .

Equation (5) is a formula for determining the mixing ratio of the red light emitting diode, the green light emitting diode, and the blue light emitting diode for obtaining the desired output coordinates xout, yout, and has a relationship of lmR + lmG + lmB = 1 lm. In order to convert the brightness of the desired output to the value of lm, the brightness can be determined by multiplying lmR, lmG, and lmB obtained through Equation (5) by a desired output value.

For example, when the values of lmR, lmG, and lmB for obtaining the desired output coordinates are 0.3, 0.4, and 0.3, and the value of the output lm is 500 lm, the combination of the red light emitting diode, the green light emitting diode, and the blue light emitting diode is 500 By multiplying it, it can be determined to have 150 lm, 200 lm, 150 lm.

By adjusting the duty cycle for driving the light emitting diodes based on the determined lm value, it is possible to realize illumination with desired brightness and color.

However, in order to adjust the brightness, the duty cycle of the driving signal is changed, thereby causing a change in the current flowing through the light emitting diode. Thus, it is difficult to accurately control the color to be implemented by changing the characteristics of the light emitting diode as shown in FIG.

2 is a graph in which a color coordinate moves according to a current.

Referring to FIG. 2, it can be seen that the x coordinate value and the y coordinate value move according to the amount of current flowing in the LED, as described above. Accordingly, it is difficult to accurately control the color of the light emitting diode to be controlled.

3 is a schematic configuration diagram of the LED driving apparatus of the present invention.

Referring to FIG. 3, the LED driving apparatus 100 of the present invention may include a control unit 110 and a driving unit 120.

The controller 110 may provide a PWM signal for driving the light emitting diode to the driving unit 120 according to brightness values and color coordinate values included in brightness information and color coordinate information input from the outside.

The control unit 110 can obtain the color coordinate value as in Equation 5 using the CIE 1931 XYZ coordinate system to control the color of the light emitting diode as described above.

XR, xG, yG, xB, and yB of the red light emitting diode, the green light emitting diode, and the blue light emitting diode can be obtained. Accordingly, the first through third driving units 121, And the duty cycle of the PWM signal can be varied according to the color coordinate values xR, yR, xG, yG, xB, yB of the red light emitting diode, the green light emitting diode, and the blue light emitting diode.

The first to third driving units 121, 122 and 123 can drive the red light emitting diode, the green light emitting diode and the blue light emitting diode, respectively, which are respectively operated according to the PWM signal.

In this case, the color coordinate values xR, yR, xG, yG, xB, yB of the red light emitting diode, the green light emitting diode and the blue light emitting diode can be shifted according to the amount of current flowing in the light emitting diode, YR, xG, yG, xB, and yB of the red light emitting diode, the green light emitting diode, and the blue light emitting diode according to the input brightness value.

Adjustment of the color coordinate values xR, yR, xG, yG, xB, yB of the red light emitting diode, the green light emitting diode and the blue light emitting diode may be performed based on the lookup table 111 according to the input brightness value.

4 is an embodiment of a look-up table used in the LED driving apparatus of the present invention.

Referring to FIG. 4 together with FIG. 3, the lookup table 111 stores x color coordinate values of red light emitting diodes, green light emitting diodes, and blue light emitting diodes, and y color coordinate values of red light emitting diodes, green light emitting diodes, and blue light emitting diodes, It can be seen that the color coordinate values xR, yR, xG, yG, xB and yB are respectively adjusted.

For example, if the input brightness value is greater than a preset reference brightness value, the x-coordinate value of the red light-emitting diode may increase and the y-coordinate value of the red light-emitting diode may decrease.

That is, if the inputted brightness value is less than 100 lm, the x color coordinate value is 0.6952, but if the input brightness value is 100 lm or more and 220 lm or less, the x color coordinate value can be adjusted to 0.6965.

Similarly, if the input brightness value is less than 100 lm, the y color coordinate value is 0.2974, but if the input brightness value is 100 lm or more and less than 220 lm, the y color coordinate value can be adjusted to 0.2972.

For example, if the input brightness value is greater than a predetermined reference brightness value, the x-coordinate value of the green LED may decrease, the y-coordinate value of the green LED may increase, The x-coordinate value of the blue light emitting diode increases and the y-coordinate value of the blue light emitting diode may decrease.

That is, if the input brightness value is 80lm or less, the x color coordinate value of the green light emitting diode is 0.2833, but if the input brightness value is 80lm or more and 240lm or less, the x color coordinate value of the green light emitting diode can be adjusted to 0.2738, If it is 240 lm or more and 370 lm or less, the x-color coordinate value of the green light emitting diode can be adjusted to 0.2655.

In addition, if the input brightness value is 80lm or less, the y color coordinate value of the green light emitting diode is 0.6883, but if the input brightness value is 80lm or more and 240lm or less, the y color coordinate value of the green light emitting diode can be adjusted to 0.6929, If it is 240 lm or more and 370 lm or less, the y color coordinate value of the green light emitting diode can be adjusted to 0.6932.

Similarly, if the input brightness value is less than 13lm, the x color coordinate value of the blue light emitting diode is 0.1358 and the y color coordinate value is 0.0571, but if the input brightness value is equal to or greater than 13lm and less than 60lm, the x color coordinate value of the blue light emitting diode can be adjusted to 0.1386 And the y color coordinate value can be adjusted to 0.0508.

The look-up table as described above is an embodiment. Referring to a graph in which a color coordinate moves according to the current shown in FIG. 2, x-coordinate values of red light emitting diodes, green light emitting diodes, and blue light emitting diodes y color coordinate values. In a section where the color coordinate value moves rapidly according to the current, the range of the brightness value for adjusting the x color coordinate value and the y color coordinate value may be adjusted to set the lookup table.

5 is a flow chart showing a control method of the LED driving apparatus of the present invention.

Referring to FIG. 5 together with FIG. 5, the control method of the LED driving apparatus of the present invention will be described. First, the controller 110 receives the brightness value and the color coordinate value of the LED to be controlled, The brightness values of the green light emitting diode and the blue light emitting diode can be determined (S10, S20).

At this time, the x coordinate value and the y coordinate value of each of the red light emitting diode, the green light emitting diode, and the blue light emitting diode can be selected from the lookup table 111 according to the brightness values of the red light emitting diode, the green light emitting diode, and the blue light emitting diode S30).

The controller 110 determines brightness ratio ratios of the red light emitting diode, the green light emitting diode, and the blue light emitting diode according to the x-coordinate values of the selected red light emitting diode, the green light emitting diode, and the blue light emitting diode, The first and third driving units 121, 122 and 123 may drive the red light emitting diode, the green light emitting diode and the blue light emitting diode, respectively, to be operated according to the PWM signal having the determined ratio (S50).

As described above, according to the present invention, a desired color can be accurately expressed by adjusting an input color coordinate value according to an input brightness value.

In addition, since no separate sensor or feedback circuit is employed, the circuit area and manufacturing cost can be reduced.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the particular forms disclosed. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100 ... LED driving device
110 ... control unit
120 ... drive unit
121 ... first driving section
122 ... second driving section
123 ... third driving section

Claims (5)

A controller for controlling driving of the light emitting diode by adjusting a color coordinate value based on an input brightness value of a light emitting diode to be controlled; And
A driving unit for driving the light emitting diode under the control of the control unit;
≪ / RTI >
The controller increases the x color coordinate value of the red light emitting diode and decreases the y color coordinate value, decreases the x color coordinate value of the green light emitting diode, and decreases the y color coordinate value of the red light emitting diode when the brightness value input by the user is equal to or greater than a preset reference brightness value Increases the x color coordinate value of the blue light emitting diode and decreases the y color coordinate value to adjust the input color coordinate value.
2. The apparatus according to claim 1, wherein the drive unit
A first driver for driving a red light emitting diode under the control of the controller;
A second driver for driving a green light emitting diode under the control of the controller; And
A third driver for driving a blue light emitting diode under the control of the controller,
And a light emitting diode driving device.
The method according to claim 1,
Wherein the control unit includes a look-up table having a color coordinate value set according to a brightness value, and adjusts the received color coordinate value according to the received brightness value.
4. The apparatus of claim 3, wherein the look-
A red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, a red light emitting diode, and a blue light emitting diode, .
Determining a brightness value of the red light emitting diode, the green light emitting diode, and the blue light emitting diode based on the brightness value and the color coordinate value of the light emitting diode to be controlled;
The x-coordinate values and the y-coordinate values of the red light emitting diode, the green light emitting diode and the blue light emitting diode are compared with preset lookup tables according to the determined brightness values of the red light emitting diode, the green light emitting diode and the blue light emitting diode, Selecting a color coordinate value moving according to an amount of a current in consideration of the color coordinate value; And
Determining a ratio of brightness values of the red light emitting diode, the green light emitting diode, and the blue light emitting diode according to a selected x color coordinate value and a y color coordinate value of each of the red light emitting diode, the green light emitting diode, and the blue light emitting diode, and a received brightness value;
, ≪ / RTI &
The look-up table includes x-color coordinate values and y-color coordinate values of the red light emitting diodes according to the brightness of the red light emitting diodes, x-color coordinate values and y-color coordinate values of the green light emitting diodes according to the brightness of the green light emitting diodes, The x color coordinate value and the y color coordinate value of the blue light emitting diode,
If the brightness value input by the user is equal to or greater than a preset reference brightness value, the x color coordinate value of the red light emitting diode is increased, the y color coordinate value is decreased, the x color coordinate value of the green light emitting diode is decreased, Wherein the x coordinate value of the blue light emitting diode is increased and the y coordinate value is decreased to adjust the input color coordinate value.

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