JP5926836B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device using an LED as a main light source. In particular, the present invention relates to an illuminating device for the purpose of renewing lighting in a place where continuous dimming has been performed using an existing incandescent light bulb, or installing lighting in a place where an incandescent light bulb atmosphere is desired.

  Recently, the main light source of lighting fixtures is rapidly shifting to LEDs. At the same time, in Japan, manufacturers are withdrawing from the incandescent bulb production business one after another at the request of the government. For this reason, LEDs are expected as an alternative to incandescent bulbs. However, many LED lamps that reproduce the same color temperature as when the incandescent bulb is fully lit have been released by each manufacturer, but one of the characteristics of the incandescent bulb is that it has a characteristic that the color temperature decreases as it darkens. Very few have been reproduced. Incandescent bulbs have been in the world since the 19th century, and it is well known that the spectral distribution of synchrotron radiation is close to that of blackbody radiation due to the principle of light emission, and it is a lighting that has little discomfort for people who have lived in the sun for many years. Therefore, it is desired to reproduce this inexpensively with LEDs.

  There is an LED module in which a monochromatic LED element and a white LED element are mounted and each element group is wired independently (for example, refer to Patent Document 1).

JP 2005-1000079 A JP 2010-176985 A JP 2008-505433 A JP 2010-192842 A

  In the prior art, although a wide range of color temperatures can be adjusted, it is impossible to simultaneously increase or decrease the brightness of light synthesized from the LEDs and to adjust the color temperature. For this reason, only by increasing or decreasing the brightness of each LED, it has not been possible to reproduce the characteristic of the incandescent light bulb that becomes darker and at the same time lowers the color temperature.

  An object of the present invention is to obtain, for example, a characteristic in which the color temperature is lowered at the same time as darkening only by increasing or decreasing the brightness of the synthesized light.

A lighting device according to one embodiment of the present invention includes:
A light source that emits white first light and orange second light;
A dimming unit for dimming the light source so that the color temperature of the combined light becomes lower as the brightness of the combined light of the first light and the second light becomes darker;
The dimming unit is configured such that the brightness of the second light decreases as the brightness of the first light decreases and the brightness of the first light decreases as the brightness of the first light decreases. The light source is dimmed so that the rate of change in light brightness is increased.

  According to one aspect of the present invention, it is possible to obtain a characteristic in which the color temperature is lowered at the same time as darkening only by increasing or decreasing the brightness of the combined light.

FIG. 3 is a circuit diagram illustrating a configuration of the lighting apparatus according to Embodiment 1; (Table 1) Comparison table of color temperature and brightness of warm white LED, (Table 2) Comparison table of color temperature and brightness of incandescent bulb. (Table 3) Comparison table of color temperature and brightness when the brightness of only the orange LED is variable. (Table 4) A comparison table of color temperature and brightness when the brightness of only the warm white LED according to Embodiment 1 is variable. (Table 5) A comparison table of color temperature and brightness when the brightness of both the warm white LED and the orange LED according to Embodiment 2 is variable. (Table 6) Comparison table of color temperature and brightness when brightness of both warm white LED and orange LED according to Embodiment 3 is variable. (Table 7) Comparison table of color temperature and brightness when brightness of both warm white LED and orange LED according to Embodiment 4 is variable. 3 is a graph corresponding to Tables 1 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis. 3 is a graph corresponding to Tables 3 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis. 3 is a graph corresponding to Tables 4 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis. 3 is a graph corresponding to Tables 5 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis. 3 is a graph corresponding to Tables 6 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis. 3 is a graph corresponding to Table 7 and Table 2, with the color temperature on the vertical axis and the brightness on the horizontal axis.

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

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing a configuration of lighting apparatus 10 according to the present embodiment.

  In FIG. 1, the illumination device 10 includes an LED lighting device 10 a, a first LED 25, and a second LED 26. The LED lighting device 10a is an example of a dimming unit, lights the first LED 25 and the second LED 26, and dimmes the first LED 25 and the second LED 26. The first LED 25 emits light having a color temperature of 2500 K (Kelvin) or more and 5000 K or less. In the present embodiment, as an example of the first LED 25, four LEDs having a color temperature of 3500K, that is, four warm white LEDs are connected in series. The second LED 26 emits light having a peak wavelength of 570 nm (nanometers) or more and 830 nm or less. Here, as an example of the second LED 26, four monochromatic LEDs having a peak wavelength of 600 nm, that is, four orange LEDs are connected in series. Note that the number of the first LEDs 25 and the second LEDs 26 may be 3 or less, or 5 or more.

  The LED lighting device 10a includes a diode bridge 11, a booster circuit 15, a first constant current output circuit 17a, a second constant current output circuit 17b, a dimming control unit 31, and a dimming controller 32. The diode bridge 11 rectifies an alternating voltage from the commercial power supply AC to generate a pulsating voltage. The booster circuit 15 is connected to the diode bridge 11 and boosts and smoothes the pulsating voltage generated by the diode bridge 11 and outputs a DC voltage. The first constant current output circuit 17 a is connected to the booster circuit 15, generates a constant current from the DC voltage output from the booster circuit 15, and outputs the constant current to the first LED 25. That is, the first constant current output circuit 17a supplies power to the first LED 25. Similarly to the first constant current output circuit 17a, the second constant current output circuit 17b is connected to the booster circuit 15, generates a constant current from the DC voltage output from the booster circuit 15, and outputs the constant current to the second LED 26. That is, the second constant current output circuit 17b supplies power to the second LED 26. The dimming control unit 31 controls the first constant current output circuit 17a and the second constant current output circuit 17b. The dimming controller 32 outputs a dimming signal to the dimming control unit 31.

  The step-up circuit 15 includes a coil 13 connected to the diode bridge 11, a diode 14 and MOSFET 18 connected to the coil 13, an electrolytic capacitor 16 connected to the output side of the diode 14, and a power factor that controls switching of the MOSFET 18. An improvement control unit 12 is provided. The booster circuit 15 switches the MOSFET 18 by the power factor correction control unit 12 and boosts the voltage input from the diode bridge 11 by self-induction of the coil 13. The booster circuit 15 smoothes and outputs the boosted voltage by the electrolytic capacitor 16 via the diode 14.

  The first constant current output circuit 17 a includes a MOSFET 19, a diode 23 and a coil 24 connected to the MOSFET 19, an electrolytic capacitor 29 connected to the coil 24, and a first control unit 21 that controls switching of the MOSFET 19. The first constant current output circuit 17a outputs a constant current to the first LED 25 connected in parallel to the electrolytic capacitor 29 by a buck converter method.

  The second constant current output circuit 17 b includes a MOSFET 20, a diode 27 and a coil 28 connected to the MOSFET 20, an electrolytic capacitor 30 connected to the coil 28, and a second control unit 22 that controls switching of the MOSFET 20. The second constant current output circuit 17b outputs a constant current to the second LED 26 connected in parallel to the electrolytic capacitor 30 by a buck converter method.

  The dimming control unit 31 receives the dimming signal output from the dimming controller 32, and outputs the output currents of the first constant current output circuit 17a and the second constant current output circuit 17b based on the input dimming signal. An output control signal for adjustment is output to the first control unit 21 and the second control unit 22. The dimming control unit 31 incorporates an algorithm for controlling the brightness and color temperature of the first LED 25 and the second LED 26. The dimming control unit 31 controls the output currents of the first constant current output circuit 17a and the second constant current output circuit 17b based on this algorithm, thereby adjusting the brightness and color temperature of the first LED 25 and the second LED 26, respectively. Control with characteristics close to the brightness and color temperature of incandescent bulbs. The dimming control unit 31 can be implemented by, for example, a microcomputer, and in this case, the algorithm can be incorporated in software executed by the microcomputer.

  The algorithm incorporated in the dimming control unit 31 uses a simple method for obtaining the correlated color temperature as the color temperature calculation method.

The correlated color temperature is determined by the CIE • 1960 • uv chromaticity diagram. The chromaticity coordinates u, v are obtained from tristimulus values X, Y, Z.
u = 4X / (X + 15Y + 3Z)
v = 6Y / (X + 15Y + 3Z)
Can be obtained. When a black body locus is drawn on the uv chromaticity diagram, the correlated color temperature can be determined by a straight line (isochromatic temperature line) orthogonal to the black body locus. However, the chromaticity coordinates u and v are not used much at present.

As an approximate expression for obtaining the correlated color temperature T from the chromaticity coordinates x, y, the following expression has been proposed (McCammy, 1992).
T = −437n ³ + 3601n ² −6861n + 5514.31
here,
n = (x−0.3320) / (y−0.1858)
It is.

  By the above formula, the color temperature can be easily calculated from the values of the chromaticity coordinates x and y described in the data sheets of the first LED 25 and the second LED 26 and the brightness ratio of the first LED 25 and the second LED 26. For example, the chromaticity coordinates (x, y) = (0.3903, 0.3826) of the first LED 25, the chromaticity coordinates (x, y) = (0.5625, 0.43) of the second LED 26, the light of the first LED 25 The output (dimming degree, brightness) is set to 100%, and the light output of the second LED 26 is set to 37%. In this case, since chromaticity coordinates (x, y) = (0.436807, 0.395401) of the illumination device 10 (the combined light of the first LED 25 and the second LED 26), n = 0.500208. Therefore, the color temperature T of the illumination device 10 is 292.9335 [K].

  FIG. 2 shows a comparison table between the color temperature and brightness of the warm white LED as Table 1, and a comparison table between the color temperature and brightness of the incandescent lamp as Table 2. FIG. 8 shows graphs corresponding to Tables 1 and 2 with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 1 shows the color temperature and brightness characteristics of a warm white LED used as the first LED 25 in the present embodiment. Table 2 shows the characteristics of the color temperature and brightness of the incandescent bulb. FIG. 8 is a graph of Tables 1 and 2 with the vertical axis representing color temperature and the horizontal axis representing brightness.

  As apparent from FIG. 8, the difference in color temperature between the LED and the incandescent bulb increases as the brightness becomes darker. This leads to a sense of incongruity when switching from incandescent bulbs to LEDs.

  FIG. 3 shows a comparison table between the color temperature and the brightness when the brightness of only the orange LED is variable with the same configuration as the illumination device 10 as Table 3. FIG. 9 shows graphs corresponding to Table 3 and Table 2 with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 3 shows the color when the warm white LED used as the first LED 25 in the present embodiment is a fixed output and the orange LED used as the second LED 26 in the present embodiment is a variable output in order to make the color temperature variable. It shows the characteristics of temperature and brightness. FIG. 9 is a graph of Tables 3 and 2, with the vertical axis representing color temperature and the horizontal axis representing brightness.

  As is apparent from FIG. 9, when the light output of the warm white LED is fixed and the light output of the orange LED is variable, the control is not successful. This makes it difficult to eliminate the uncomfortable feeling when switching from an incandescent bulb to an LED.

  FIG. 4 shows a comparison table between the color temperature and the brightness of the lighting apparatus 10 according to the present embodiment, in which the brightness of only the warm white LED is variable. FIG. 10 shows graphs corresponding to Tables 4 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 4 shows the characteristics of the color temperature and brightness of the lighting device 10 in which the warm white LED used as the first LED 25 in the present embodiment is a variable output and the orange LED used as the second LED 26 in the present embodiment is a fixed output. Is shown. FIG. 10 is a graph of Tables 4 and 2 with the vertical axis representing color temperature and the horizontal axis representing brightness.

  In the present embodiment, when the dimming control unit 31 of the LED lighting device 10a receives a dimming signal instructing the dimming degree L [%] (5 ≦ L ≦ 100) from the dimming controller 32, the first LED 25 adjusts the light. The first constant current output circuit 17a is controlled so as to be lit with a light output corresponding to the light intensity L. At this time, the dimming control unit 31 controls the second constant current output circuit 17b so that the second LED 26 lights with a constant light output regardless of the dimming degree L. That is, in the present embodiment, the light control unit 31 reduces the light output of the first LED 25 and the light output of the second LED 26 as the light control degree (target brightness of the combined light) of the lighting device 10 decreases. The first LED 25 and the second LED 26 are dimmed so that becomes constant. At this time, the change rate of the light output of the first LED 25 is constant regardless of the dimming degree. In the present embodiment, the dimming control unit 31 prevents the first LED 25 and the second LED 26 from having the same color temperature as that of the incandescent light bulb so that the color temperature does not give a strange feeling to the color temperature. The brightness is controlled.

  As apparent from FIG. 10, according to the present embodiment, it is possible to realize the characteristic that the color temperature is lowered at the same time as the darkness is reduced only by increasing or decreasing the brightness of the first LED 25. Moreover, in the present embodiment, the change rate of the color temperature of the lighting device 10 increases as the brightness of the lighting device 10 (combined light) becomes darker. For this reason, the uncomfortable feeling at the time of switching from an incandescent lamp (incandescent lamp) to LED can be suppressed.

  In the present embodiment, the LED lighting device 10a includes the dimming controller 32, but the dimming controller 32 may be provided outside the LED lighting device 10a.

  In the present embodiment, an LED having a color temperature of 3500K is used as the first LED 25, but an LED having another color temperature (for example, a range of 2500K to 5000K) may be used. In the present embodiment, a monochromatic LED having a wavelength peak of 600 nm is used as the second LED 26, but a monochromatic LED having a peak at other wavelengths (for example, a range of 570 nm to 830 nm) may be used.

  As described above, the lighting device 10 according to the present embodiment uses an LED having a color temperature of 2500 to 5000K and a single color LED having a peak wavelength of 570 to 830 nm as a light source, and simultaneously changes the brightness and the color temperature. It is characterized by making it. In addition, the lighting device 10 is characterized in that the color temperature decreases as it becomes darker.

  Due to the above features, in the present embodiment, it can be expected that the color temperature of the incandescent bulb at each brightness is inexpensively reproduced by the LED and can be used without a sense of incongruity even when the incandescent bulb is switched to the lighting device 10.

Embodiment 2. FIG.
In the present embodiment, differences from the first embodiment will be mainly described.

  Referring to FIG. 10, in the lighting device 10 according to the first embodiment, the color temperature starts to drop sharply when the brightness exceeds 50%. In addition, the illumination device 10 according to the first embodiment and the incandescent lamp have a large difference in color temperature when the brightness is 100%.

  FIG. 5 shows a comparison table between the color temperature and the brightness of the lighting apparatus 10 according to the present embodiment, in which the brightness of both the warm white LED and the orange LED is variable. FIG. 11 shows graphs corresponding to Tables 5 and 2, with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 5 shows the color temperature and brightness of the lighting device 10 in which the warm white LED used as the first LED 25 in the present embodiment has a variable output, and at the same time, the orange LED used as the second LED 26 in the present embodiment also has a variable output. The characteristics are shown. The change in light output is monotonously decreasing for both LEDs. FIG. 11 is a graph of Tables 5 and 2 with the vertical axis representing color temperature and the horizontal axis representing brightness.

  In the present embodiment, when the dimming control unit 31 of the LED lighting device 10a receives a dimming signal instructing the dimming degree L [%] (5 ≦ L ≦ 100) from the dimming controller 32, the first embodiment Similarly to the above, the first constant current output circuit 17a is controlled so that the first LED 25 lights with the light output corresponding to the dimming degree L. At this time, unlike the first embodiment, the dimming control unit 31 controls the second constant current output circuit 17b so that the second LED 26 lights with a light output corresponding to the dimming degree L. That is, in the present embodiment, the light control unit 31 reduces the light output of the first LED 25 and the light output of the second LED 26 as the light control degree (target brightness of the combined light) of the lighting device 10 decreases. The first LED 25 and the second LED 26 are dimmed so as to be smaller. That is, the dimming control unit 31 dims the first LED 25 and the second LED 26 so that the brightness of the second LED 26 becomes darker as the brightness of the first LED 25 becomes darker. At this time, the change rate of the light output of the first LED 25 and the change rate of the light output of the second LED 26 are both constant regardless of the degree of dimming. Further, in the present embodiment, the dimming control unit 31 is configured so that the color temperature near 100% brightness and 5% brightness is the same as that of the incandescent light bulb so as not to give a strange feeling to the color temperature. The brightness of the first LED 25 and the second LED 26 is controlled.

  As is clear from FIG. 11, in this embodiment, it is possible to avoid a sudden drop in color temperature from around 50% brightness as in the first embodiment. In addition, the difference in color temperature between the lighting device 10 and the incandescent light bulb when the brightness is 100% can be eliminated. For this reason, the sense of incongruity at the time of switching from an incandescent bulb to an LED can be almost eliminated.

Embodiment 3 FIG.
The difference between the present embodiment and the second embodiment will be mainly described.

  Referring to FIG. 11, in the lighting device 10 according to the second embodiment, the color temperature starts to rapidly decrease around 30% brightness. In addition, there is almost no change in color temperature at a brightness of 100 to 50%.

  FIG. 6 shows a comparison table between the color temperature and the brightness of the lighting apparatus 10 according to the present embodiment, in which the brightness of both the warm white LED and the orange LED is variable. FIG. 12 shows graphs corresponding to Tables 6 and 2 with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 6 shows the color temperature and brightness of the lighting device 10 in which the warm white LED used as the first LED 25 in the present embodiment has a variable output, and at the same time, the orange LED used as the second LED 26 in the present embodiment also has a variable output. The characteristics are shown. The change in the light output is a decrease that can be represented by a graph in which the warm white LED decreases monotonically and the orange LED protrudes upward. FIG. 12 is a graph of Tables 6 and 2 with the vertical axis representing color temperature and the horizontal axis representing brightness.

  In the present embodiment, when the dimming control unit 31 of the LED lighting device 10a receives a dimming signal instructing the dimming degree L [%] (5 ≦ L ≦ 100) from the dimming controller 32, the second embodiment. Similarly to the above, the first constant current output circuit 17a is controlled so that the first LED 25 lights with the light output corresponding to the dimming degree L. At this time, the dimming control unit 31 is different from the second embodiment in that the second constant current output circuit is configured such that the lower the dimming degree L, the larger the change amount of the light output of the second LED 26 with respect to the change amount of the dimming degree L. 17b is controlled. That is, in the present embodiment, the light control unit 31 reduces the light output of the first LED 25 and the light output of the second LED 26 as the light control degree (target brightness of the combined light) of the lighting device 10 decreases. The first LED 25 and the second LED 26 are dimmed so that becomes smaller. At this time, the change rate of the light output of the first LED 25 is constant regardless of the degree of dimming, as in the second embodiment, but the change rate of the light output of the second LED 26 is different from that of the second embodiment. It becomes higher as the dimming degree becomes smaller. In other words, the dimming control unit 31 dims the first LED 25 and the second LED 26 so that the rate of change in the brightness of the second LED 26 increases as the brightness of the first LED 25 becomes darker. In the present embodiment, the dimming control unit 31 prevents the first LED 25 and the second LED 26 from having the same color temperature as that of the incandescent light bulb so that the color temperature does not give a strange feeling to the color temperature. The brightness is controlled. Further, in the present embodiment, the dimming control unit 31 controls the brightness of the first LED 25 and the second LED 26 so that the color temperature clearly changes in the brightness range of 100 to 50%.

  As is apparent from FIG. 12, in the present embodiment, it is possible to avoid the color temperature from starting to suddenly decrease when the brightness exceeds 30%, as in the second embodiment. Further, the color temperature can be changed at a brightness of 100 to 50%. For this reason, the uncomfortable feeling at the time of switching from an incandescent lamp to LED can be suppressed.

Embodiment 4 FIG.
The difference between the present embodiment and the third embodiment will be mainly described.

  Referring to FIG. 12, in the lighting device 10 according to the third embodiment, although not as much as in the second embodiment, the color temperature starts to decrease slightly abruptly after the brightness of 30% has passed. In addition, the illumination device 10 according to the third embodiment and the incandescent light bulb cause a difference in color temperature when the brightness is 100%.

  FIG. 7 shows a comparison table between the color temperature and the brightness of the lighting apparatus 10 according to the present embodiment, in which the brightness of both the warm white LED and the orange LED is variable. FIG. 13 shows graphs corresponding to Table 7 and Table 2, with the color temperature on the vertical axis and the brightness on the horizontal axis.

  Table 7 shows the color temperature and brightness of the lighting device 10 in which the warm white LED used as the first LED 25 in the present embodiment has a variable output, and at the same time, the orange LED used as the second LED 26 in the present embodiment also has a variable output. The characteristics are shown. The change in light output is such that the warm white LED decreases monotonically and the orange LED decreases by the formula √r including the square root. R in the square root is monotonously decreased. Also in this case, the change in the light output of the orange LED is a reduction method that can be represented by a graph that is convex upward, as in the third embodiment. FIG. 13 is a graph of Tables 7 and 2 with the vertical axis representing color temperature and the horizontal axis representing brightness.

  In the present embodiment, when the dimming control unit 31 of the LED lighting device 10a receives a dimming signal instructing the dimming degree L [%] (5 ≦ L ≦ 100) from the dimming controller 32, the third embodiment. Similarly to the above, the first constant current output circuit 17a is controlled so that the first LED 25 lights with the light output corresponding to the dimming degree L. At this time, unlike the third embodiment, the dimming control unit 31 is configured to turn on the second constant current output circuit 17b so that the second LED 26 is lit with the light output represented by the square root √r of r corresponding to the dimming degree L. To control. That is, in the present embodiment, the light control unit 31 reduces the light output of the first LED 25 and the light output of the second LED 26 as the light control degree (target brightness of the combined light) of the lighting device 10 decreases. The first LED 25 and the second LED 26 are dimmed so that becomes smaller. At this time, the change rate of the light output of the first LED 25 is constant regardless of the degree of dimming, as in the third embodiment, and the change rate of the light output of the second LED 26 is also similar to the third embodiment. It becomes higher as the dimming degree becomes smaller. However, in the present embodiment, unlike the third embodiment, the dimming control unit 31 sets r as a variable that decreases at a constant change rate as the brightness of the first LED 25 becomes darker, and the brightness of the second LED 26 increases. The first LED 25 and the second LED 26 are dimmed so as to be equal to the square root √r of r.

  As is apparent from FIG. 13, in the present embodiment, a trajectory almost similar to the color temperature of the incandescent bulb can be drawn. That is, in the present embodiment, the relationship between the brightness of the lighting device 10 (combined light) and the color temperature is substantially the same as the relationship between the brightness of the incandescent lamp (incandescent lamp) and the color temperature. For this reason, even if it uses the illuminating device 10 as a substitute of an incandescent lamp, it is thought that there is no sense of incongruity at all.

  As described above, in the lighting device 10 according to the present embodiment, the relationship between the brightness and the color temperature is 2500 to 4000 K at the time of all light, and is substantially the same as the relationship between the brightness and the color temperature of the incandescent lamp. It is characterized by being.

  Due to the above features, in the present embodiment, it can be further expected that the incandescent lamp can be used without a sense of incongruity even when switched from the incandescent light bulb to the lighting device 10.

  DESCRIPTION OF SYMBOLS 10 Illuminating device, 10a LED lighting device, 11 Diode bridge, 12 Power factor improvement control part, 13 Coil, 14 Diode, 15 Booster circuit, 16 Electrolytic capacitor, 17a 1st constant current output circuit, 17b 2nd constant current output circuit, 18 MOSFET, 19 MOSFET, 20 MOSFET, 21 1st controller, 22 2nd controller, 23 diode, 24 coil, 25 1st LED, 26 2nd LED, 27 diode, 28 coil, 29 electrolytic capacitor, 30 electrolytic capacitor, 31 Dimming control unit, 32 dimming controller, AC commercial power.

Claims (5)

A light source that emits white first light and orange second light;
A dimming unit for dimming the light source so that the color temperature of the combined light becomes lower as the brightness of the combined light of the first light and the second light becomes darker;
The dimming unit is configured such that the brightness of the second light decreases as the brightness of the first light decreases and the brightness of the first light decreases as the brightness of the first light decreases. An illuminating device that dims the light source so that the change rate of the brightness of the light is increased.   The lighting device according to claim 1, wherein the light control unit adjusts the light source such that a change rate of a color temperature of the composite light increases as a brightness of the composite light becomes dark.   3. The illumination according to claim 1, wherein the light control unit adjusts the light source so that a relationship between the brightness of the combined light and the color temperature is the same as a relationship between the brightness of the incandescent lamp and the color temperature. apparatus.   The dimming unit sets r as a variable that decreases at a constant change rate as the brightness of the first light becomes dark, and makes the brightness of the second light equal to the square root √r of r. The lighting device according to claim 1, wherein the light source is dimmed. The first light so that the color temperature of the combined light becomes lower as the brightness of the combined light of the first light color light that is white light and the second light color light that is orange light becomes darker. A light control unit for adjusting the color light and the second light color light;
The dimming unit is configured such that the brightness of the second light color light becomes darker as the brightness of the first light color light becomes darker and the second light light becomes darker as the brightness of the first light color light becomes darker. An illumination device that adjusts the first light color light and the second light color light so that a change rate of brightness of the color light is increased.

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