JP5016427B2 - LED lighting device - Google Patents

Description

  The present invention relates to an LED illumination device that emits illumination light using an LED as a light source.

  Conventionally, a red, green, and blue LED and a photodiode that receives the combined light are provided, and the tristimulus value of the combined light is measured using the photodiode, and a desired color temperature is determined based on the measurement result. There is known an LED illumination device that independently controls a current value supplied to each LED in order to irradiate synthetic light as illumination light (see, for example, Patent Document 1).

By the way, the light obtained by synthesizing the three colors of light has a large change in light intensity with respect to wavelength in the emission spectrum, so that it is easily recognized as artificial light and has a low color rendering index. Therefore, in the technique disclosed in Patent Document 1, illumination light can be irradiated with a desired color temperature. However, since the illumination light is a combined light of three colors, the color rendering index is low.
JP-T-2004-525516

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an LED illumination device capable of irradiating illumination light having a desired color temperature with a high color rendering index.

  In order to achieve the above object, the invention of claim 1 is based on a plurality of LEDs, a power source for lighting the LEDs, an optical sensor for measuring the brightness of light of the LEDs, and an output of the optical sensor. A control unit that controls a current supplied from the power source to the LED, and a setting unit for setting a color temperature of the combined light of the LED, and the plurality of LEDs are , Consisting of four types of LEDs having different peak wavelengths of emission spectrum, and two types of LEDs having adjacent peak wavelengths among the four types of LEDs are connected in series and supplied with current from the same power source, The control unit stores a tristimulus value coefficient obtained from the tristimulus values of the combined light of the two types of LEDs measured in advance and the light of each other LED and the photosensor output value at that time. The The target tristimulus value of the combined light of the four types of LEDs is calculated based on the color temperature set by the setting unit, and the two types of LEDs among the four types of LEDs and the other LEDs, A current of a predetermined value is sequentially supplied from the power source to measure the brightness of the combined light of the two kinds of LEDs and the light of each of the other LEDs using the optical sensor, and the output value of the optical sensor at that time And the tristimulus value coefficient stored in the storage unit, the tristimulus values of the combined light of the two types of LEDs and the light of each of the other LEDs are estimated, and the combined light of the estimated two types of LEDs and Based on the tristimulus value of the light of each of the other LEDs and the target tristimulus value, the current supplied to the two types of LEDs and the other LEDs is controlled.

  According to a second aspect of the present invention, in the LED lighting device according to the first aspect, the plurality of LEDs are red, green, blue and orange or yellow LEDs.

  According to the first aspect of the invention, since the light emission control by the four types of LEDs is performed so that the color temperature of the combined light of the LEDs becomes the color temperature set by the setting unit, the combined light of the desired color temperature is emitted. It can be irradiated as illumination light. Furthermore, since the degree of change of the light intensity with respect to wavelength in the emission spectrum of the combined light is smaller than that of the conventional combined light of three colors, the combined light is irradiated with a high color rendering index. be able to.

  According to the invention of claim 2, since red, green, and blue LEDs are included, it is possible to irradiate light of all colors as illumination light.

Hereinafter, LED lighting devices according to various embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 shows the configuration of the LED lighting device according to the first embodiment. The LED lighting device 1 includes a plurality of LEDs 2, a power source 3 for lighting the LEDs 2, a light sensor 4 that measures the brightness of light of the LEDs 2, and a current supplied from the power source 3 to the LEDs 2. And a setting unit 6 for setting the color temperature and brightness of the combined light of the LED 2 based on the user's operation. The plurality of LEDs 2 are composed of four types of LEDs having different peak wavelengths in the emission spectrum. Among the four types of LEDs, two types of LEDs having adjacent peak wavelengths are connected in series, and are supplied from the same power source 3. Current is supplied. The control unit 5 calculates the target tristimulus value of the illumination light based on the color temperature and brightness set by the setting unit 6, and supplies a predetermined value from the power source 3 to the two types of LEDs and the other LEDs. Are sequentially supplied to estimate the tristimulus values of the combined light of the two types of LEDs and the light of each of the other LEDs. And the control part 5 is supplied to 2 types of LED and each other LED based on the tristimulus value and target tristimulus value of the estimated light of said 2 types of said LED, and each other LED light. Control the current. The setting unit 6 includes an operation button or an operation panel operated by the user for setting the color temperature and brightness, and sends a signal based on the user operation to the control unit 5. The unit of brightness to be set is lux or the like.

  The plurality of LEDs 2 includes a red LED 21, an orange LED 22, a green LED 23, and a blue LED 24 (hereinafter referred to as a red LED 21 or the like). Among these, two types of LEDs having adjacent peak wavelengths, that is, a red LED 21 and an orange LED 22 are electrically connected in series. The number of red LEDs 21 or the like may be singular or plural. Since the plurality of LEDs 2 include the red LED 21, the green LED 23, and the blue LED 24, it is possible to irradiate light of all colors as illumination light.

  The power source 3 includes a power source 31 that supplies the same current to the red LED 21 and the orange LED 22, a power source 32 that supplies current to the green LED 23, and a power source 33 that supplies current to the blue LED 24. The power supplies 31 to 33 (hereinafter referred to as the power supply 31 and the like) supply a current by sending a pulse train-like current signal to the red LED 21 and the like. The power supply 31 or the like controls the supply current value to the red LED 21 or the like by modulating the peak value or the duty ratio of the current signal. The supply current value is controlled based on a control signal sent from the control unit 5. The optical sensor 4 is composed of a brightness sensor composed of a photodiode.

  The control unit 5 includes a storage unit 51 that stores various data for calculating target tristimulus values of illumination light and estimating tristimulus values of the red LEDs 21 and the like. Further, the control unit 5 refers to the storage unit 51 and performs various calculations such as calculation of target tristimulus values of illumination light, combined light of the two types of LEDs, and estimation of tristimulus values of other LED lights. And an arithmetic unit 52 for controlling a current value supplied to the LED 2 by the power source 31 and the like. The calculation unit 52 is configured by a microprocessor including a CPU. Detailed operation of the calculation unit 52 will be described later.

  The storage unit 51 is configured by a storage medium such as a ROM, a RAM, or a flash memory. This storage medium includes a chromaticity coordinate table 51a for calculating a target tristimulus value shown in FIGS. 2A and 2B, combined light of the above two types of LEDs (red LED 21, orange LED 22), and other A tristimulus value coefficient table 51b for estimating tristimulus values of light of each LED (green LED 23, blue LED 24) is stored.

  The chromaticity coordinate table 51a shows the correspondence between the color temperature and the chromaticity coordinate values (x, y, z). Therefore, referring to the chromaticity coordinate table 51a, the chromaticity coordinate value corresponding to the color temperature set by the setting unit 6 is obtained, and the brightness value set by the setting unit 6 is obtained as the obtained chromaticity coordinate value. The target tristimulus value can be calculated by multiplying by.

  In the tristimulus value coefficient table 51b, tristimulus value coefficients obtained from the tristimulus values of the combined light of the above-described two kinds of LEDs and the light of the other LEDs and the output value of the optical sensor 4 at the time of measurement are stored in the tristimulus value coefficient table 51b. Is stored. Specifically, the tristimulus values of the combined light of the red LED 21 and the orange LED 22 and the light of each of the green LED 23 and the blue LED 24 (hereinafter referred to as the combined light of the red LED 21 and the orange LED 22 etc.) at the time of an inspection process before shipment, etc. , And the tristimulus value coefficients (r1, r2, r3), (g1, g2, g3) obtained by dividing the tristimulus value at that time by the output voltage of the optical sensor 4 at the time of measurement, (B1, b2, b3) are stored.

  Here, a measurement example of tristimulus values such as synthesized light of the red LED 21 and the orange LED 22 and a calculation example of tristimulus value coefficients will be described. First, as shown in FIGS. 3 to 5, the spectroscope 7 capable of measuring the tristimulus value of light is electrically connected to the calculation unit 52 by an inspector or the like during an inspection process before shipment. . The calculation unit 52 detects the connection with the spectroscope 7 or the operation of the setting unit 6 by an inspector or the like as a trigger, and sequentially inputs a red LED 21, an orange LED 22, a green LED 23, and a blue LED 24 from the power supply 31 and the like to a predetermined number. Supply current and turn them on sequentially. In FIG. 3 to FIG. 5, the red LED 21 and the like that are turned off are indicated by broken lines.

  Each time the light is turned on, the spectroscope 7 measures the tristimulus value of light and sends the measurement data to the calculation unit 52, and the calculation unit 52 measures the brightness of the light using the optical sensor 4. The calculation unit 52 calculates the tristimulus value coefficient by dividing the tristimulus value measured by the spectroscope 7 by the output voltage of the optical sensor 4. Accordingly, the tristimulus value can be calculated by multiplying the tristimulus value coefficient by the output voltage of the optical sensor 4. For this reason, once the tristimulus values such as the combined light of the red LED 21 and the orange LED 22 are measured once before shipment, the tristimulus values are estimated without measuring the tristimulus values after shipment. Is possible.

  FIG. 6 shows an LED control process of the calculation unit 52 in the LED lighting device 1 configured as described above. Based on the signal from the setting unit 6, the calculation unit 52 recognizes the set color temperature and brightness in the illumination light, that is, the combined light such as the red LED 21 (S1).

  Then, the calculation unit 52 acquires the chromaticity coordinate value corresponding to the set color temperature with reference to the chromaticity coordinate table 51a of the storage unit 51 (S2), and is set to the acquired chromaticity coordinate value. A target tristimulus value is calculated by multiplying the brightness (S3). For example, when the set color temperature is 3000 [K] and the set brightness is 1000 [lx], as shown in the chromaticity coordinate table 51a, the color corresponding to the color temperature 3000 [K] Since the degree coordinate value is (x, y, z) = (0.436, 0.402, 0.162), the target tristimulus value is obtained by multiplying the chromaticity coordinate value by brightness ( 4360, 4020, 1620).

  Next, the calculation unit 52 controls the current supplied from the power source 31 and the like to the red LED 21 and the like, and sequentially turns on the red LED 21, the orange LED 22, the green LED 23, and the blue LED 24 (S4). At this time, the supply current value to the red LED 21 and the orange LED 22 is R, the supply current value to the green LED 23 is G, and the supply current value to the blue LED 24 is B. R, G, and B are predetermined current values, for example, maximum current values. At the time of lighting, the calculation unit 52 measures the brightness of the combined light of the red LED 21 and the orange LED 22 and the brightness of the light of each of the green LED 23 and the blue LED 24 using the light sensor 4, and outputs the light sensor 4. The voltages Vr, Vg, and Vb are recognized (S5).

上記の数１のように、三刺激値係数（ｒ１、ｒ２、ｒ３）、（ｇ１、ｇ２、ｇ３）、（ｂ１、ｂ２、ｂ３）に光センサ４の出力電圧Ｖｒ、Ｖｇ、Ｖｂを乗じることで、赤色ＬＥＤ２１及び橙色ＬＥＤ２２の合成光等の三刺激値が推定される。 After the brightness measurement, the calculation unit 52 refers to the tristimulus value coefficient table 51b of the storage unit 51 for the tristimulus value coefficients (r1, r2, r3), (g1, g2, g3), (b1, b2, b3). (S6). Then, the arithmetic unit 52 uses the mathematical formula shown in the following equation 1 to calculate the tristimulus values (Xr, Yr, Zr) of the combined light of the red LED 21 and the orange LED 22, and the light of each of the green LED 23 and the blue LED 24. Tristimulus values (Xg, Yg, Zg) and (Xb, Yb, Zb) are estimated (S7).

Multiplying the tristimulus value coefficients (r1, r2, r3), (g1, g2, g3), (b1, b2, b3) by the output voltages Vr, Vg, Vb of the optical sensor 4 as shown in Equation 1 above. Thus, the tristimulus values such as the combined light of the red LED 21 and the orange LED 22 are estimated.

  After the tristimulus value is estimated, based on the estimation result, the supply current value to the red LED 21 and the orange LED 22 necessary for the tristimulus value of the illumination light, that is, the combined light of the red LED 21 and the like to be the target tristimulus value, A supply current value to each of the green LED 23 and the blue LED is calculated. And according to the calculation result, an electric current is supplied to each of red LED21 and orange LED22, green LED23, and blue LED24, and it controls independently (S8).

Here, an example of calculating the above supply current value will be described. The tristimulus value of the illumination light is a value obtained by adding the tristimulus values of the respective lights of the red LED 21 and the like, so it is necessary to first obtain the ratio of the tristimulus values to the whole. Accordingly, the calculation unit 52 solves the ternary linear simultaneous equation represented by the following Equation 2 with the target tristimulus values as (X ₀ , Y ₀ , Z ₀ ) and the variables as α, β, and γ.

演算部５２は、上記の数３の数式を解いて求めた供給電流値Ｉｒ、Ｉｇ、Ｉｂでもって赤色ＬＥＤ２１等に電流を供給するように指示する制御信号を電源３１等に送出し、目標三刺激値の照明光を赤色ＬＥＤ２１等から出射させる。 By the way, the tristimulus value of light changes according to the brightness of light, and the brightness of light changes with the change of the supply current value to the LED 2. For this reason, the solutions of α, β, and γ in the above equation 2 are obtained and multiplied by the above-described supply current values R, G, and B as shown in the following equation 3, so that the tristimulus of illumination light is obtained. It is possible to calculate the supply current value Ir to the red LED 21 and the orange LED 22 and the supply current values Ig and Ib to the green LED 23 and the blue LED, which are necessary for the value to become the target tristimulus value.

The calculation unit 52 sends a control signal instructing to supply current to the red LED 21 and the like with the supply current values Ir, Ig, and Ib obtained by solving the above mathematical formula 3, to the power source 31 and the like. Stimulus value illumination light is emitted from the red LED 21 or the like.

  In the present embodiment, light emission control by the red LED 21 or the like, that is, light emission control by four types of LEDs, so that the color temperature and brightness of the combined light from the red LED 21 or the like becomes the color temperature and brightness set by the setting unit 6. Is done. For this reason, it is possible to irradiate synthetic light having a desired color temperature as illumination light, and to reduce the degree of change of light intensity with respect to wavelength in the emission spectrum of the synthetic light, compared to the conventional synthetic light of three colors of light. can do. Therefore, the combined light from the red LED 21 or the like can be irradiated with a high color rendering index, and light closer to natural light can be obtained.

  Further, a target tristimulus value is calculated based on the color temperature set by the setting unit 6, and the red LED 21 is calculated by the calculation unit 52 so that the tristimulus value of the combined light of the red LED 21, that is, the illumination light becomes the target tristimulus value. Therefore, the user can irradiate illumination light having a desired color temperature by setting the color temperature of the illumination light to a desired value using the setting unit 6.

  In addition, since the red LED 21 and the orange LED 22 are connected in series and current is supplied from the same power source, they can be regarded as one type of LED as a group to be controlled. For this reason, four types of LEDs, that is, red LEDs 21 and the like can be controlled so as to control three types of LEDs. For this reason, complication of control accompanying increase in the type of LED can be prevented.

(Second Embodiment)
FIG. 7 shows a configuration of the LED illumination device according to the second embodiment. In the LED lighting device 1 of the present embodiment, the red LED 21 and the orange LED 22 are arranged such that the number h of illumination lights, that is, the color rendering evaluation number of the combined light of the red LED 21, the orange LED 22, the green LED 23, and the blue LED 24 is the highest. i is set. For this reason, in this embodiment, the color rendering evaluation number of illumination light can be made higher than in the first embodiment, and the illumination light can be made light closer to natural light. In this embodiment, the same effect as that of the first embodiment can be obtained.

(Third embodiment)
FIG. 8 shows a configuration of an LED lighting device according to the third embodiment. Compared with the configuration of the first embodiment, the LED illumination device 1 of the present embodiment includes a yellow LED 25 instead of the orange LED 22, and a plurality of yellow LEDs 25 are provided. At least one yellow LED 25 is connected in series with a red LED 21 having a peak wavelength adjacent thereto, and a current is supplied from a power supply 31. Further, the yellow LED 25 different from the above is connected in series with the green LED 23 having an adjacent peak wavelength, and current is supplied from the power supply 32. In this embodiment, the same effect as that of the first embodiment can be obtained.

  In addition, this invention is not limited to the structure of the said 1st thru | or 3rd embodiment, A various deformation | transformation is possible according to a use purpose. For example, in the first embodiment, the optical sensor 4 may be configured by a color sensor instead of a brightness sensor. The setting unit 6 may set the chromaticity of the combined light such as the red LED 21. In this case, the target tristimulus value of the synthetic light is calculated based on the set chromaticity. In the third embodiment, the yellow LED 25 may be connected in series only to either the red LED 21 or the green LED 23.

The block diagram of the LED lighting apparatus which concerns on the 1st Embodiment of this invention. (A) is a figure which shows the chromaticity coordinate table stored in the memory | storage part of the said apparatus, (b) is a figure which shows the tristimulus value coefficient table stored in the memory | storage part. The block diagram which shows the measurement example of the tristimulus value of LED of the said apparatus. The block diagram which shows the measurement example of the tristimulus value of LED of the said apparatus. The block diagram which shows the measurement example of the tristimulus value of LED of the said apparatus. The flowchart of the LED control processing by the calculating part of the said apparatus. The block diagram of the LED lighting apparatus which concerns on the 2nd Embodiment of this invention. The block diagram of the LED lighting apparatus which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

1 LED lighting device 2 LED
21 Red LED
22 Orange LED
23 Green LED
24 Blue LED
25 Yellow LED
3, 31-33 Power supply 4 Optical sensor 5 Control unit 51 Storage unit 51a Chromaticity coordinate table 51b Tristimulus value coefficient table 52 Calculation unit 6 Setting unit

Claims (2)

Based on a plurality of LEDs, a power source for lighting the LEDs, a light sensor that measures the brightness of light of the LEDs, and an output of the light sensor, a current supplied from the power source to the LEDs is controlled. And an LED lighting device comprising:
A setting unit for setting the color temperature of the combined light of the LED;
The plurality of LEDs are composed of four types of LEDs having different peak wavelengths of the emission spectrum, and two types of LEDs having adjacent peak wavelengths among the four types of LEDs are connected in series and are connected to the same power source. Current is supplied,
The controller is
Having a storage unit for storing tristimulus value coefficients obtained from the pre-measured combined light of the two types of LEDs and the tristimulus values of the light of each other LED and the light sensor output value at that time;
The target tristimulus value of the combined light of the four types of LEDs is calculated based on the color temperature set by the setting unit, and the two types of the four types of LEDs and the other LEDs A current of a predetermined value is sequentially supplied from a power source, and the brightness of the combined light of the two types of LEDs and the light of each of the other LEDs are respectively measured using the photosensors. According to the tristimulus value coefficient stored in the storage unit, the combined light of the two kinds of LEDs and the tristimulus value of the light of each other LED are estimated,
Controlling the current supplied to the two types of LEDs and the other LEDs based on the estimated tristimulus values of the combined light of the two types of LEDs and the light of each of the other LEDs and the target tristimulus value. LED lighting device characterized by this.   The LED lighting device according to claim 1, wherein the plurality of LEDs are red, green, blue, orange, or yellow LEDs.

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