JP5285137B2 - Dimming control based on HLS color space of full color LED - Google Patents

Description

The present invention relates to dimming control of a full color LED composed of a single LED of a plurality of colors.

Conventionally, when a color is output by a full color LED, it is carried out by additive color mixing based on the RGB color space. In the present application, this method is called an RGB composition method. The RGB composition method is a method of outputting the target color by individually adjusting the luminance of the single color LED constituting the full color LED. The color expression method has an HLS color space that focuses on human color sensation, and has elements of hue, lightness, and saturation. The diffusion control described in Patent Document 1 is an RGB composition method because the brightness of single-color LEDs constituting a full-color LED is adjusted. In the present application, an LED that displays a single color instead of a full-color LED is referred to as a single-color LED, and what is simply referred to as a single-color LED is a single-color LED constituting the full-color LED.

Japanese Patent No. 4740377

It is difficult to dimm the target color by the RGB composition method that adjusts the luminance of the single-color LED configured by using the full-color LED. Dimming based on the HLS color space that is close to the human sense having elements of hue, saturation, and lightness instead of the RGB composition method is performed at a low manufacturing cost.

When a full color LED is used, the problem is that the current used is larger than that of a single single color LED, and the color reproducibility is poor due to various characteristics of the plurality of full color LEDs.

Select a single color LED, the lighting timing and the lighting ratio for the single color LED that constitutes the full color LED that is necessary for determining the hue of the color output using the full color LED within a fixed period. A single array arranged in chronological order with the elements to be adjusted, while limiting the number of single-color LEDs that can be lit at any hue to one to enhance the color adjustment function, the desired hue is emitted by repeating the cycle. .

There is a single array that can express hue or lightness with elements arranged in time series arranged to emit a specific color using a full-color LED, and this array is repeated at a fixed period to constitute a full-color LED In dimming that controls lighting of single-color LEDs, an array that repeats with a fixed period is replaced with a different array at an appropriate time in a longer period to output an intermediate color resulting from a plurality of arrays, and the number of single-color LEDs that are lit is limited to one. While improving the color adjustment function, the color of the full-color LED is adjusted by the hue, saturation, and brightness, which are elements of the HLS color space, to emit light.

According to the first aspect of the present invention, the dimming of the full-color LED can be adjusted by each element of hue, saturation, and brightness based on the HLS color space close to human sense. Furthermore, since the method to be used does not require a complicated circuit, the manufacturing cost is low.

By controlling the number of single-color LEDs to be lit to one, no matter what color the current used in the full-color LED is dimmed, it is equivalent to a single single-color LED. This reduces the capacity of the power supply used in equipment that uses full-color LEDs.

By controlling the number of single-color LEDs to be lit to one, the reproducibility of the problematic color is improved due to various characteristics different among the plurality of LEDs. This generally simplifies the process of selecting the LEDs to be used and ensuring the color identity in the process of manufacturing a device that uses a plurality of full-color LEDs.

Configuration diagram showing the overall configuration of the present invention Explanatory drawing of control arrangement by hue diffusion control Explanatory drawing of the control arrangement by hue diffusion control with a distorted hue circle as the reproduction target Illustration of dispersion period and neutral color control

FIG. 1 shows the overall structure of the present invention. Each single-color LED that constitutes a full-color LED includes a red LED drive circuit (LED-R), a green LED drive circuit (LED-G), and a blue LED drive circuit (LED-B). Connect with control signals from the chip. In the present application, a microchip refers to a microchip that can define a program structure and can process a control signal to the outside by program control.

Each LED drive circuit of LED-R, LED-G, and LED-B controls each LED with two values of lighting and extinguishing by a control signal output from the microchip. In the present application, the lighting of the LED is referred to as ON, and the extinguishing is referred to as OFF.

The dimming control is performed by the development technology based on the technology of diffusion control by the program structure in the microchip. Diffusion control is a control method described in Patent Document 1, and the purpose is to adjust the brightness by ON and OFF for each single color LED by an array that repeats with a fixed period in which the single color LEDs constituting the full color LED are held internally. Output color. Further, the array arranged in the time series of ON and OFF used at this time is called a diffusion format, and a cycle in which the diffusion format is repeated is called a diffusion cycle.

In the diffusion control, each single color LED constituting the full color LED is synchronously controlled. The monochromatic LED necessary for obtaining the specific hue is developed exclusively by developing the control.

During the ON period determined by the diffusion control, one single-color LED output of two colors for determining the hue is turned on, and when the OFF period is set, another single-color LED for determining the hue is lit. In other words, in the diffusion control, the ON and OFF control, which was performed to adjust the brightness of the single color LED, is changed to the control that switches on and switches on the two single color LEDs, and the single diffusion control performed for each single color LED is integrated. Are output as a single control array. A control array is a sequence of elements for determining the selection of a single color LED to be controlled, the lighting timing and the lighting ratio in time series, and is an ON / OFF array prepared for each single color LED used in diffusion control. It is different from the diffusion form. Since the cycle for repeating the control array is the same as the diffusion cycle, the cycle for repeating the control array is called a diffusion cycle. The important point in this control is to control the light by limiting the single-color LED to be lit to one. This control method is called hue diffusion control and is shown as hue diffusion control 1 in FIG. The hue diffusion control 2 is also controlled in the same manner, but the target hue is different from the hue diffusion control 1. FIG. 2 shows, as an example, a control arrangement implemented at three blending ratios by hue diffusion control for red (R) and blue (B).

In the hue diffusion control by any two of the three single-color LEDs constituting the full-color LED, a hue circle in which all the colors are aligned becomes a reproduction target. This hue circle is referred to as a normal hue circle in the present application. In hue diffusion control by a combination other than two single-color LEDs, a biased hue circle lacking a partial hue other than the normal hue circle is a reproduction target. This hue circle is referred to as a distorted hue circle in the present application. A unique color effect can be obtained by switching the reproduction target from a normal hue circle to a distorted hue circle. The combination when a distorted hue ring is a reproduction target includes a lighting period in which a plurality of single-color LEDs are handled as one. In the hue diffusion control, the single-color LEDs that are lit are limited to one. In the lighting period when the LEDs are handled as one, the single color LEDs are turned on in order. As an example, FIG. 3 shows a control arrangement implemented at three blending ratios by hue diffusion control using a distorted hue ring using red (R) and blue (B) without using green (G) as a reproduction target. . At this time, red (R) and blue (B) are handled in a single color, and a combination of red + blue (R + B) is used instead of green (G). Although it is similar to FIG. 2, the proportion of monochromatic LEDs and the timing of lighting are different. As another example, a pastel color when hue diffusion control is performed with red + blue (R + B), blue + green (B + G), and green + red (G + R), which is a single color LED instead of a single color LED. The distorted hue circle is the reproduction target.

When dimming an intermediate color with a full-color LED, if two colors are lit simultaneously using the RGB composition method, the luminance increases and the saturation decreases. Even when displaying intermediate colors, suppressing the increase in luminance while maintaining the hue as a full color LED has the effect of increasing the saturation. In the hue diffusion control , the number of single-colored LEDs that are lit is limited to one, and the RGB composition method suppresses the phenomenon that the saturation is lowered.

In the hue diffusion control according to the first aspect of the present invention, the hue adjustment range is wide as compared with the method of adjusting the luminance of the monochromatic LED by ON and OFF. That is, in the hue diffusion control, dimming is performed while always lighting any one of the LEDs from the state where one single-color LED constituting the hue is continuously lit to the state where the other single-color LED is continuously lit. Dimming without turning off the single color LED expands the hue adjustment range by maximizing the luminance of the single color LED with continuous lighting.

In the hue diffusion control , the current to be used is made equal to that of a single single-color LED by limiting the single-color LED to be lit to one. In other words, even a full-color LED composed of a plurality of single-color LEDs operates with the same power supply capacity as when a single single-color LED is used.

In the RGB composition method, the target color is determined as the composition of the luminance of the single color LED, so that the same hue can be obtained in a device using a plurality of full color LEDs due to variations in the luminance of the single color LEDs constituting the full color LED. Is difficult. Hue diffusion control that limits the single color LED to be lit and adjusts the target hue by switching the single color LED reduces the influence on the hue due to the luminance difference of the single color LED and improves the color reproducibility.

For lightness adjustment, a control array having a different purpose from the control array output by hue diffusion control is required. One is a control array B that turns off all the single color LEDs constituting the full color LED and outputs the minimum brightness, and the other is a control array W that lights all the single color LEDs constituting the full color LED at the same ratio and outputs the maximum brightness. become. Control for creating a control array necessary for brightness adjustment is called brightness diffusion control and is shown in FIG. The lightness diffusion control is performed for the purpose of adjusting the lightness in the control array output by the hue diffusion control. When the control array W is output by lightness diffusion control, the single-color LED to be lit is limited to one as in the case of hue diffusion control. In the present application, the color by the control array W is set to 100% lightness and the color from the control array B is set to 0% lightness regardless of the brightness displayed by the full color LED.

Separate control arrays created by the hue diffusion control 1, the hue diffusion control 2, and the lightness diffusion control are passed to the next intermediate color control. The intermediate color control corresponding to claim 1 of the present invention is to output the intermediate color between the control arrays by arranging the control arrays created by the hue diffusion control 1, the hue diffusion control 2 and the lightness diffusion control in a fixed period longer than the diffusion period. The control method is called and shown as the intermediate color control in FIG. The important point of this control is to output the intermediate color from the control array already having hue and lightness elements. The proportion in which the control sequence is blended is determined by the target color effect. The period in which the control arrays are distributed at this time is referred to as a dispersion period, and the dispersion period needs to be shortened until the included control arrays cannot be recognized as separate colors. As an example, FIG. 4 shows the intermediate color control and the dispersion period performed at three blending ratios by the control array A and the control array B.

Two control arrays that output colors close to the intermediate color control are passed to further subdivide the two hues. This smoothes the display color change of the entire full color LED and increases the resolution of the target hue.

Saturation adjustment is performed by passing two control arrays for outputting colors separated as hues to the intermediate color control . It is perceived that the color on the hue circle is formed as an extreme blending ratio, but the intermediate color between two distant hues shifts to a neutral blending ratio and the saturation decreases. The most effective combination of hues for saturation adjustment is an intermediate color between hues in complementary colors, and the saturation decreases to the maximum when the blending ratio is approximately half.

The control array for outputting one hue for the intermediate color control and the control array B or the control array W prepared for adjusting the brightness are passed, and the brightness is adjusted while maintaining the hue. In the present application, the color output by the hue diffusion control is set to 50% brightness, the brightness of 50% or less is adjusted by executing the control array B and the intermediate color control, and the control array W and the intermediate color control is adjusted to 50%. Adjust the above brightness. In the hue diffusion control with a normal hue circle as a reproduction target, the single color LEDs constituting the full color LED are not turned off, but the single color LED is turned off only after the intermediate color control with the control array B is performed.

Intermediate color control works from three or more control arrays, but intermediate color control performed with three or more control arrays requires a longer dispersion period to obtain the same color effect compared to intermediate color control using two control arrays. . For this purpose, the target color effect is selected, and intermediate color control performed from two control arrays is fundamental.

Hue , saturation and brightness are adjusted by hue diffusion control and intermediate color control . A method of dimming with these elements is regarded as an HLS color space. The dimming control method of the present invention, in which the color of the full-color LED is determined by adjusting the elements of the HLS color space, is superior to the dimming control method using the RGB composition method because it is easy to judge the color sensuously.

A control signal derived from the intermediate color control is output from the microchip, and the full color LED is turned on by the LED-R, LED-G, and LED-B drive circuits.

1. . . Hue diffusion control 1,2. . . Hue diffusion control 2,3. . . 3. Lightness diffusion control . . Intermediate color control, 5. . . . 5. Red LED drive circuit (LED-R), . . 6. Green LED drive circuit (LED-G) . . Blue LED drive circuit (LED-B), 8. . . Microchip

Claims (1)

Prepared to emit a specific color using a full-color LED, as an element for lighting a single color LED, the lighting timing and lighting time of a plurality of single color LEDs with different emission colors are included. In the dimming that controls the single color LED that constitutes the full color LED by using the control array in the diffusion period and controls the single-color LED constituting the full-color LED in order to bring about the dimming effect with the longer dispersion period. A dimming control method that outputs an intermediate color provided by a plurality of control arrays, timely interchanges with another necessary control array, and adjusts the emission color of a full-color LED by hue, saturation, and brightness.

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