JP2013004398A - Led lighting system and led arrangement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting system excellent in color rendering and color reproducibility and capable of changing color temperature with high efficiency, and an arrangement method of the LED.SOLUTION: The LED lighting system comprises an LED group comprising a plurality of LEDs, an LED package having at least one LED group, and a control part for controlling the LED package. The LED group is provided with at least one blue LED arranged in the center of the LED group, at least two red LEDs arranged symmetrically to the central point of the LED group in the surrounding of the blue LED, at least two green LEDs arranged in positions opposed to the red LEDs and symmetrically to the central point in the surrounding of the blue LED, and at least two white LEDs arranged in the surrounding of the blue LED.

Description

  The present invention relates to a lighting device using a light emitting diode (hereinafter referred to as “LED”) and a method of arranging LEDs in the lighting device.

  With the advent of pseudo-white LEDs and the improvement in luminous efficiency accompanying technological advances, various attempts have been made to commercialize lighting devices using LEDs as light sources. By using an LED as a light source, it is possible to achieve higher energy efficiency than incandescent bulbs that have been frequently used as a conventional light source, and further, the device can be reduced in size, weight, and life.

  An example of an LED illumination device using a pseudo white LED as a light source is described in Patent Document 1. In addition to pseudo white LEDs, lighting devices using green, red, and blue LEDs as light sources are also known. The LED illumination device described in Patent Document 2 is configured to obtain white light by combining three primary colors of light by combining green, red, and blue LEDs.

JP 2011-60678 A JP 2010-262868 A

  Generally, a pseudo white LED obtains yellow light by exciting a phosphor with blue light, and obtains pseudo white light by mixing the yellow light and blue light. By using such a pseudo white LED, it is possible to obtain a light source with high power-light conversion efficiency. However, the pseudo-white LED has wavelength peaks around 460 nm and 560 nm and lacks other wavelength components, so that the color rendering property that reproduces the original color of the illuminated material is poor. In particular, when a red or green substance is illuminated, these colors may appear dull. Therefore, for example, in a place where it is required to reproduce the original color of an art object such as a museum, it is not preferable to use a pseudo white LED as the light source of the lighting device. In addition, when the pseudo white LED is used, the color temperature of the illumination cannot be freely changed.

  On the other hand, in the LED lighting device described in Patent Document 2, by using three color LEDs, color rendering properties and color reproducibility can be improved as compared with the case where pseudo white LEDs are used. However, in order to obtain white light by mixing three colors of green, red, and blue, it is necessary to mix green, red, and blue at a ratio of about 7: 3: 1, which is inefficient. Specifically, the power-to-light conversion efficiency of each color LED is different, and in order to obtain white at the above ratio, it is necessary to take measures such as increasing the number of green LEDs. Therefore, in order to obtain a luminance equivalent to that of one white LED, it is necessary to drive a plurality of LEDs, and the power-light conversion efficiency is deteriorated. Further, when white light is obtained from LEDs of a plurality of colors, the luminance decreases at different rates depending on the emission color over time, and color misregistration occurs. Therefore, there is a problem that some correction means is required to eliminate the color misregistration.

  Therefore, the present invention has been made in view of the above problems, and provides a highly efficient LED lighting device and an LED arrangement method that are excellent in color rendering and color reproducibility, can change the color temperature. With the goal.

  In order to solve the above-described problems, the present invention provides an LED lighting device including an LED group including a plurality of LEDs, an LED package including at least one LED group, and a control unit that controls the LED package. The LED group of the present invention includes at least one blue LED arranged at the center of the LED group and at least two red LEDs arranged symmetrically with respect to the center point of the LED group around the blue LED. An LED, at least two green LEDs arranged around the blue LED, symmetrically with respect to the central point and opposite the red LED, and at least two white LEDs arranged around the blue LED And. Further, the LED group may include at least two blue LEDs. In this case, at least two blue LEDs may be arranged symmetrically with respect to the center point.

  The white LED may be disposed between the red LED and the green LED, and the number of the white LEDs may be larger than the number of each of the red, blue, and green LEDs. Further, the number of red LEDs may be larger than the number of blue LEDs and green LEDs. Further, the at least two white LEDs may include at least one white light bulb LED.

  Further, according to the present invention, there is provided an LED arrangement method in an LED lighting device including an LED group composed of a plurality of LEDs, an LED package including at least one LED group, and a control unit that controls the LED package. At least one blue LED in the middle of the LED, at least two red LEDs around the blue LED, symmetrically with respect to the center point of the LED group, and at least two around the blue LED An LED arrangement method is provided, wherein green LEDs are arranged symmetrically with respect to a center point and at positions facing red LEDs, and at least two white LEDs are arranged around blue LEDs. .

  In the LED illumination device of the present invention, excellent color rendering and color reproducibility can be realized, and the color temperature of illumination can be changed in a wide range. Furthermore, by arranging the LEDs of each color in a well-balanced manner, it is possible to realize a highly efficient lighting device without color unevenness.

It is the schematic which shows the LED lighting apparatus in embodiment of this invention. It is a circuit diagram which shows the LED drive circuit in the LED lighting apparatus of FIG. It is a figure which shows arrangement | positioning of LED in the LED package of FIG. It is a figure which shows arrangement | positioning of LED in another embodiment of this invention.

  Hereinafter, an LED lighting device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing an LED lighting device 1 according to an embodiment of the present invention. The LED lighting device 1 includes a plurality of LED packages 200 and a control unit 500. The LED package 200 is an LED substrate on which a plurality of white, blue, green, and red LEDs are mounted, as will be described later. The control unit 500 is a control unit for driving and controlling the LED package 200. In the LED lighting device 1, four LED packages 200 connected in series are regarded as one block, and are driven by the control unit 500 for each block. In the example of FIG. 1, four blocks (16 LED packages 200) are driven by the control unit 500. Note that the number of LED packages 200 in series is not limited to four, and a larger or smaller number of LED packages 200 can be connected in series to form one block according to the luminance required for the lighting device.

  FIG. 2 is a circuit diagram showing the LED driving circuit 120 per block in the LED lighting device 1. The LED driving circuit 120 includes a plurality of LED driving units 20W, 20B, 20G, and four LED packages 200 each including a plurality of LED units 10W, 10B, 10G, and 10R, and each LED unit 10W to 10R. 20R and a plurality of current control units 30W, 30B, 30G and 30R. The LED driving units 20W to 20R supply a current for driving each LED unit, and the power control units 30W to 30R control a current flowing through each LED driving unit. In addition, VD shown in FIG. 2 is an LED power source, and VE is a driving unit power source.

  Here, since the configurations of the LED units 10W to 10R, the LED driving units 20W to 20R, and the current control units 30W to 30R are substantially the same, the LED unit 10W, the LED driving unit 20W, and the current control unit 30W are taken as an example. A detailed configuration of the LED drive circuit 120 will be described.

In this embodiment, a feedback type constant current circuit is used as the current control unit 30W. Specifically, the current control unit 30W includes a reference voltage setting unit 35W for setting a current value supplied to the LED unit 10W. The reference voltage setting unit 35W includes a variable resistor Rv, and can change the reference voltage by changing the value of the variable resistor Rv. That is, the current flowing through the LED unit 10W is set to a desired value by the variable resistor Rv. Further, the current control unit 30W includes an amplifier 31W. The amplifier 31W receives the reference voltage set by the reference voltage setting unit 35W as one input, and information on the current value of the LED drive unit 20W connected to the LED unit 10W. To the other input via a feedback circuit composed of feedback resistors Rf ₁ and Rf ₂ .

  The LED driving unit 20W includes a driving transistor Tr, and an emitter resistance Re and a base resistance Rb are connected to an emitter and a base of the driving transistor Tr, respectively. Information on the current value flowing through the LED unit 10W is detected as a voltage generated in the emitter resistor Re. And the electric current which flows into LED unit 10W is each controlled by inputting the detected voltage value into the amplifier 31W via a feedback circuit.

LED unit 10W is five white LED1 _W and one resistor R10W is series connected LED string _{2 W} is configured five columns, are connected in parallel. In the present embodiment, a pseudo white LED is used as the white LED 1 _w , which obtains pseudo white light using a technique of exciting a phosphor with blue light to obtain yellow light.

Here, since the LED Vf (forward voltage) varies depending on individual differences, when the LED is simply connected in series and parallel and driven at constant current, the LED row having the smallest total value of Vf is obtained. Current flows in a concentrated manner. As a result, only some of the LED rows are lit brightly, while some of the LED rows are hardly illuminated. To prevent such a problem, in the present embodiment, the LED units 10 W, a resistor R10W by inserting into each LED column 2 _W, the difference between the current flowing through each LED column is suppressed from occurring.

  Further, the value of the resistor R10W of the present embodiment is calculated as follows. First, when n stages of LEDs are connected in series, a voltage difference of (Vfmax−Vfmin) × n at the maximum occurs in each LED row. Here, Vfmax is the maximum value of Vf of LED1, and Vfmin is the minimum value of Vf of LED. Therefore, by setting the voltage drop value of the resistor R10W connected in series to be k times the voltage difference, the variation in Vf can be absorbed. Here, it is desirable to set k to a value of at least 3 or more, and by making it larger (for example, around 10), variations can be almost ignored. However, since the loss of voltage due to the resistor R10W increases by setting k large, it is practical to set k to a value around 5 in consideration of the balance between variation absorption and loss.

Next, the arrangement of LEDs in the LED package 200 of the present embodiment will be described with reference to FIG. In the present embodiment, the LED package 200 is mounted with 25 white LEDs 1 _w , 10 blue LEDs 1 _B and 10 green LEDs 1 _G , respectively, and 14 red LEDs 1 _R. Here, in general, the Vf of a red LED is lower than the Vf of LEDs of other colors due to its material. Therefore, in this embodiment, in order to balance the Vf value in each LED unit, the number of the red LED1 _R is green, it is increasingly compared to the number of blue LED. By increasing the number of red LEDs in this way, it is possible to reduce wasted power burdened by the current control unit (reduce loss), and the efficiency of the LED lighting device 1 is improved. Furthermore, the same power supply voltage can be used for driving each color LED, and the types of power supply voltages to be used can be reduced. Further, since the red LED is relatively inefficient, the efficiency can be improved by increasing the number of other LEDs than other LEDs, and the control for producing a white color becomes easy.

Further, as shown in FIG. 3, each LED is distributed to an LED group 100 located at the center of the LED package 200 and four LED groups 110 located around the LED group 100. Specifically, the LED group 100 includes five white LEDs 1 _w and two red LEDs 1 _R , a green LED 1 _G, and a blue LED 1 _B , and the LED group 110 includes two white LEDs 1 _w , two each. Green LED 1 _G and blue LED 1 _B, and three red LEDs 1 _R.

In the LED group 100, the two blue LEDs 1 _B are arranged in the center of the LED group 100 so as to be symmetric with respect to the virtual optical center point A. In general, human sensitivity to blue LEDs is low compared to other colors. Therefore, even when a blue LED is arranged in the center, there is an advantage that blue is not recognized by a person. Further, the two red LEDs 1 _R are arranged so as to be symmetric with respect to the center point A around the blue LED 1 _B. Then, two green LED1 _G is also around the blue LED1 _B, are symmetrical with respect to the center point A, is disposed and the red LED1 to face the _R position. Thus, by arranging the red LED and the green LED close to each other, the red and green LEDs are mixed, and the occurrence of color unevenness is suppressed. Further, the five white LEDs 1 _W are arranged so as to fill the periphery of the blue LED 1 _B so as to be substantially symmetric with respect to the center point A. As described above, by arranging the white LEDs between the LEDs of the respective colors, the light from the red, green, and blue LEDs is mixed with the light from the white LEDs, and a clearer white can be obtained.

Furthermore, the LED group 110, the LED substantially similarly to the LED group 100 is disposed, the number of the red LED1 _R than LED group 100 is different only in one more. Here, the LED package 200 does not need to include the two types of LED groups 100 and 110, and may be configured by only the LED group 100 or only the LED group 110. Since the LED groups 100 and 110 can obtain well-balanced white light as a single unit, the system can be expanded / reduced by arbitrarily increasing or decreasing the number of the LED groups 100 and 110.

  Thus, in the LED lighting device 1 of the present embodiment, excellent color rendering and color reproducibility can be realized by providing red, green, and blue LEDs in addition to white LEDs. Moreover, in this embodiment, it is possible to change the color temperature of illumination in a wide range by providing a predetermined number (34 in total) of red, green, and blue LEDs for 25 white LEDs. It has become. Furthermore, it is not necessary to set the ratio of red, green, and blue LEDs to 7: 3: 1 by mixing four colors of LEDs to obtain white, thus realizing a high-luminance lighting device without reducing efficiency. In addition, the color misregistration associated with the elapsed time can be kept low enough to be ignored.

FIG. 4 is a diagram showing the arrangement of LEDs in the LED package 201 according to another embodiment of the present invention. In the present embodiment, in the arrangement shown in FIG. 3, two of the five white LEDs 1 _W included in the LED groups 101 and 111 are replaced with light bulb-colored white LEDs 1 _WD . In this case, the two white LEDs 1 _WD are arranged symmetrically with respect to the center point A. At this time, color unevenness can be prevented by disposing each white LED 1 _{WD not} in the red LED 1 _R but in the vicinity of the green LED 1 _G. Thus, the color developability of the LED lighting device 1 can be further improved by using a part of the white LED as a light bulb color white LED. In addition, said effect can be acquired by making at least 1 white LED into white LED _1WD of a light bulb color.

The above is the description of the exemplary embodiments of the present invention. Specific aspects of the embodiments of the present invention are not limited to those described above, and can be arbitrarily changed within the scope of the technical idea expressed by the description of the scope of claims. For example, in the present embodiment, 34 red, green, and blue LEDs are used for 25 white LEDs, but the number of each LED and the ratio of the white LED to the red, green, and blue LEDs are as follows. Can be arbitrarily changed. Increasing the ratio of red, green, and blue LEDs broadens the range of color temperature changes, and increasing the ratio of white LEDs increases efficiency. For example, by setting the ratio of white LEDs to red, green, and blue LEDs to 9: 1, sufficient color rendering and color reproducibility can be obtained, but it is difficult to change the color temperature. In the above embodiment has a configuration to place two symmetrically with respect to the center point blue LED1 _B in the center of the LED group 100, it may be disposed only one at the center.

  Further, the number of LEDs in each LED row in each LED unit 10W to 10R and the number of LED rows in parallel are not limited to five or seven, but are based on the luminance required for the device and the number of LEDs. Is set as appropriate. However, since the power supply voltage value increases by increasing the number of LEDs in series and the number of parallel connections, from the viewpoint of safety, the number of series and the number of parallel connections are set so that the power supply voltage value is a predetermined value or less (for example, 48 V or less). May be set. Furthermore, although the feedback type constant current circuit is used as the current control unit, the present invention is not limited to this, and other known circuits can be used as the current control unit.

1 LED lighting device 1 _W to 1 _R LED
2 _W to 2 _R LED string R10W~R10R resistance 10W～10R LED unit 20W～20R LED driver 30W~30R current controller 31W~31R amplifier 35W~35R reference voltage setting unit 100, 110 LED group 120 LED driving circuit 200 LED Package 500 control unit

Claims (7)

An LED lighting device including an LED group including a plurality of LEDs, an LED package including at least one LED group, and a control unit that controls the LED package,
The LED group is
At least one blue LED disposed in the center of the LED group;
Around the blue LED, at least two red LEDs arranged symmetrically with respect to the center point of the LED group;
Around the blue LED, at least two green LEDs arranged symmetrically with respect to the center point and facing the red LED;
At least two white LEDs disposed around the blue LED;
An LED lighting device comprising: The LED group comprises at least two blue LEDs;
The LED lighting device according to claim 1, wherein the at least two blue LEDs are arranged symmetrically with respect to the center point.   The LED illumination device according to claim 1, wherein the white LED is disposed between the red LED and the green LED.   4. The LED lighting device according to claim 1, wherein the number of the white LEDs is larger than the number of each of the red, blue, and green LEDs. 5.   5. The LED lighting device according to claim 1, wherein the number of the red LEDs is larger than the number of each of the blue LEDs and the green LEDs.   The LED lighting device according to claim 1, wherein the at least two white LEDs include at least one light bulb color white LED. An LED arrangement method in an LED illumination device comprising an LED group comprising a plurality of LEDs, an LED package comprising at least one LED group, and a control unit for controlling the LED package,
Placing at least one blue LED in the center of the LED group;
Around the blue LED, at least two red LEDs are arranged symmetrically with respect to the center point of the LED group,
Around the blue LED, at least two green LEDs are arranged symmetrically with respect to the center point and at a position facing the red LED,
Arrange at least two white LEDs around the blue LED;
The LED arrangement method characterized by the above-mentioned.

Images