JP6210405B2 - Lighting device - Google Patents

Description

  The present invention relates to an illumination device that can adjust the illuminance and color temperature of irradiated light.

  2. Description of the Related Art Conventionally, there has been known a lighting device that includes not only a fluorescent lamp as a light source but also an LED that can emit light with high luminance at low power, and is used on a desk as a reading lamp (for example, see Patent Document 1). In the illumination device described in Patent Document 1, the LED is arranged at the center of the lamp, and an annular fluorescent lamp is arranged so as to surround the LED. When the LED is turned on, irradiation light like a spotlight is obtained, and when the fluorescent lamp is turned on, irradiation light irradiated on the entire desk is obtained. Thus, by individually controlling the lighting of the LED and the fluorescent lamp, it is possible to adjust the light distribution and illuminance of the irradiation light.

  Moreover, in the illumination device provided with the two types of light sources as described above, the light sources are configured to emit light having different color temperatures, and the illuminance and color of the irradiation light are controlled by controlling the output ratio of the light sources. There is one in which the temperature can be adjusted (see, for example, Patent Document 2). Such an illuminating device performs dimming control of the light source so that the color temperature increases as the illuminance of the irradiation light increases.

JP 2006-12755 A JP-A-2005-243406

  When the illumination device described in Patent Documents 1 and 2 as described above is used as, for example, a reading lamp, generally, the readability of characters is improved by increasing the illuminance of irradiation light. However, when the illuminance is increased, the irradiation light becomes dazzling, so that it is easy to feel tired eyes and it is difficult to perform long-term visual work. In addition, unnecessarily high illuminance leads to wasted energy.

  The present invention solves the above-mentioned problems and makes it difficult to feel tired eyes even if the illumination intensity of the irradiation light is increased in order to improve the readability of characters, and enables long-term visual work. And it aims at providing the illuminating device which can aim at energy saving.

The illumination device of the present invention includes a first light source unit that emits light of a predetermined color temperature, a second light source unit that emits light of a color temperature different from the first light source unit, and the first light source unit. A light source unit and a control unit that performs dimming control on the second light source unit individually, and the control unit has an illuminance of irradiation light from the illumination device of 300 to 1500 lx and a color temperature of 5000 to 7000K. in the range, varied to inverse correlation between intensity and color temperature, and at the time of low illuminance gradually changing the color temperature in accordance with the illuminance change, so as to abruptly change the color temperature in accordance with the illuminance change in a high illuminance And adjusting an output ratio between the first light source unit and the second light source unit.

  It is preferable that the first light source unit includes a white LED that emits white light having a color temperature of 4500 to 5500K, and the second light source unit includes a blue LED that emits blue light.

The control unit, it is preferable to change the illuminance of the irradiation light Te range odor 500～1000Lx.

  The illuminating device further includes an elapsed time measuring unit that measures an elapsed time since the first light source unit and the second light source unit are turned on, and the control unit is timed by the elapsed time measuring unit. As the elapsed time increases, it is preferable to adjust the output ratio between the first light source unit and the second light source unit so as to lower the illuminance of the irradiation light and increase the color temperature of the irradiation light.

  According to the present invention, when the illuminance of the irradiation light is increased, the color temperature is lowered, so that the dazzling of the irradiation light can be suppressed even if the illuminance of the irradiation light is increased in order to improve the readability of characters. This makes it difficult to feel tired of the eyes and enables long-term visual work. Further, when the illuminance of the irradiation light is lowered, the color temperature is increased. Therefore, it is possible to save energy by reducing the illuminance while maintaining the legibility of characters.

The perspective view of the illuminating device which concerns on embodiment of this invention. The block diagram which shows the structure of the said illuminating device. The figure which shows the relationship between the illumination intensity in various color temperature, and the readability feeling of a character. The figure which shows the relationship between the color temperature of the light radiate | emitted from LED, and the luminous efficiency ratio of the LED. (A) is an xy chromaticity diagram showing a chromaticity distribution of light emitted from a light source combining a white LED and various blue LEDs, and (b) is an enlarged view of a region surrounded by a two-dot chain line in (a). . (A) is sectional drawing of the 1st light source part which comprises the said illuminating device, (b) is sectional drawing of a 2nd light source part, (c) is the 2nd light source part of an example different from (b). FIG. The spectral distribution map of the irradiation light irradiated from the said illuminating device. (A) and (b) are the figures which show the relationship between the illumination intensity of the irradiation light irradiated from the said illuminating device, and color temperature. The block diagram which shows the structure of the illuminating device which concerns on the modification of the said embodiment.

  An illumination device according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the lighting device 1 is used as a desk stand, for example, and is mounted on a desk with a long lamp 11, an arm 12 that holds the lamp 11 movably, and an arm 12 that is pivotally supported. And a base 13 to be provided.

  The lamp 11 includes a first light source unit 2 that emits light having a predetermined color temperature, and a second light source unit 3 that emits light having a color temperature different from that of the first light source unit 2 (FIG. 2). See also). The first light source unit 2 and the second light source unit 3 are both configured by LEDs, and in the illustrated example, the first light source unit 2 and the second light source unit 3 are arranged fourth and ninth from one end among a total of twelve LEDs arranged in a row. The LED (shown by dots) is the second light source unit 3, and the other LEDs are the first light source unit 2.

  The lamp 11 includes a control unit 4 that performs dimming control of the first light source unit 2 and the second light source unit 3 individually, and a dimming and toning curve that defines a dimming control mode by the control unit 4 (see below). ). The control unit 4 includes a microcomputer, a switch, and the like, and adjusts the power supply from the commercial power supply to the first light source unit 2 and the second light source unit 3, so that the first light source unit 2 and the second light source are adjusted. The output ratio with the unit 3 is adjusted.

  The base 13 has a dial-like operation unit 6 that is attached to itself so as to be rotatable and is used to adjust the illuminance and color temperature of the irradiation light emitted from the lamp 11. When the user rotates the operation unit 6, the amount of change in the illuminance and color temperature of the irradiation light is determined based on the dimming toning curve according to the amount of rotation, and the illuminance and color temperature change by the amount of change. Thus, the control unit 4 controls power feeding to the first light source unit 2 and the second light source unit 3.

  When the illuminating device 1 was used as a reading lamp, an experiment was conducted to examine the relationship between the illuminance and color temperature of the irradiation light emitted from the illuminating device 1 and the readability of characters. In this experiment, a xenon lamp that emits visible light of any wavelength was combined with a liquid crystal filter, and irradiation light with various color temperatures was generated by controlling the translucency of the liquid crystal filter. The color temperature to be tested is 4 levels of 2700K, 5000K, 6000K and 7000K based on the color temperature range 2700-7000K of white light described in "Classification by light source color and color rendering of fluorescent lamp" of JISZ9112. Selected. As the illuminance to be tested, five levels of 300 lx, 500 lx, 600 lx, 750 lx and 1000 lx were selected.

  Under the test light temperature and test illumination intensity as described above, the test subject evaluated the readability of the test characters. The test characters were 30 characters printed at 7 points, which is the size of newspaper newspaper, in the center of plain paper, and the subjects read it at a viewing distance of 40 cm. The subjects were 30 males and females aged 23-69 years old, and the text readability was “very easy to read”, “pretty easy to read”, “somewhat easy to read”, “neither”, “somewhat difficult to read”, They were selected and evaluated from “very difficult to read” and “very difficult to read”. 3 points for “very easy to read”, 2 points for “very easy to read”, 1 point for “slightly easy to read”, 0 for “neither”, 1 for “slightly difficult to read”, “ The sense of readability was quantified, with "very difficult to read" being -2 points and "very difficult to read" being -3 points.

  As an experimental procedure, the illuminance is increased in the order of 300 lx, 500 lx, 600 lx, 750 lx, and 1000 lx under the irradiation light of the color temperature randomly selected from the above four levels of test color temperatures, and the test at each illuminance is performed. We had you evaluate readability of letter. First, adaptation was performed for 3 minutes on plain paper on which test characters were not printed at an illuminance of 300 lx, and then the test characters were silently read for 10 seconds, and then the test characters were subjected to subjective evaluation for readability. In subsequent experiments with an illuminance of 500 lx or more, adaptation on plain paper was performed for 1 minute, and after subjective evaluation at an illuminance of 1000 lx, the color temperature was changed and the same experiment was repeated.

  As a result, as shown in FIG. 3, it was found that the higher the color temperature, the higher the readability, and the higher the illuminance, the better the readability. However, the method of improving the readability differs depending on the color temperature. For example, the illuminance is almost proportional to the readability at a color temperature of 2700 K (indicated by a white circle), whereas the illuminance is improved at other color temperatures. When it exceeded 600 lx, the sense of readability almost reached its peak.

  In the above experiment, the relationship between the illuminance of irradiated light at various color temperatures and the readability of characters was examined. FIG. 4 is a plot of the luminous efficiency of the LEDs at various color temperatures. The luminous efficiency is shown as a luminous efficiency ratio normalized by the luminous efficiency at a color temperature of 5000K. As is clear from FIG. 4, the luminous efficiency ratio was the highest at the color temperature of 5000K, and was lowered regardless of whether the color temperature was increased from 5000K or decreased. Therefore, from the viewpoint of luminous efficiency, it is preferable to cause the LED to emit light at a color temperature of 5000K.

  Returning to FIG. 3, when the illuminance of the irradiated light is 1500 lx (indicated by a point P) at a color temperature of 5000 K (indicated by a white inverted triangle) where the luminous efficiency of the LED is the highest, the sense of readability is approximately 1.4. Met. Here, in order to reduce the illuminance while maintaining this sense of readability, the color temperature is increased to 6000K (indicated by the point Q) as shown by the dotted arrow in the figure, and the color temperature is further increased to 7000K (point It can be seen that it may be increased to (indicated by R).

  In order to increase the color temperature of the irradiation light from 5000K to 7000K as described above, a white LED that emits white light having a color temperature of 5000K and a blue LED that emits blue light having a color temperature higher than that of white light are provided. It is conceivable to adjust the output ratio of these LEDs in combination. Therefore, as shown in FIGS. 5 (a) and 5 (b), a white LED and various blue LEDs that emit blue light each having a different main wavelength are combined, and the light of any color temperature in each combination. We investigated whether it could be obtained. The blue LEDs tested emitted blue light having dominant wavelengths at 450 nm, 460 nm, 470 nm, 480 nm and 490 nm, respectively. In the figure, white triangles indicate chromaticity points when white LEDs and respective blue LEDs are combined at a luminous flux ratio of 99: 1, and white squares indicate white LEDs and respective blue LEDs at a luminous flux ratio of 96. : Indicates the chromaticity point when combined at 4.

  As a result, when a white LED and a blue LED that emits blue light having a dominant wavelength of 480 nm are combined, the light of the daylight color classification (see FIG. 5B) that can be suitably used as the irradiation light of the desk stand is efficient. It turns out that it gets well. In the example shown in the drawing, the range of light obtained by mixing blue light in the wavelength range of 475 to 485 nm and white light from the white LED is represented by dots in consideration of the main wavelength of blue light being 480 nm. Show. The daylight color classification referred to here is the daylight color classification described in “Classification by light source color and color rendering of fluorescent lamp” of JISZ9112, the upper limit of Duv is 15, the lower limit is −4, and the color The upper limit of temperature is 7100K and the lower limit is 5700K.

  As described above, by combining a white LED that emits white light with a color temperature of 5000 K and a blue LED that emits blue light having a dominant wavelength in the wavelength range of 475 to 485 nm, it is possible to efficiently obtain daylight color division light. it can. Therefore, in the present embodiment, the first light source unit 2 includes a white LED that emits white light having a color temperature of 5000K, and the second light source unit 3 includes blue light having a dominant wavelength in the wavelength region of 475 to 485 nm. A blue LED that emits light. Here, the color temperature of the white light emitted from the first light source unit 2 does not have to be strictly 5000K, and may be in the range of 4500 to 5500K.

  As shown to Fig.6 (a), the 1st light source part 2 is the LED chip 21, the base 22 which accommodates LED chip 21, the sealing material 23 which seals LED chip 21, and a sealing material. And a phosphor 24 that is dispersed in the light source 23 and emits light from the LED chip 21 after wavelength conversion. The LED chip 21 is composed of a gallium nitride blue LED chip that emits blue light having a main wavelength of 450 nm. The base 22 has a concave portion 22a whose inner diameter decreases in the center toward the bottom surface, and the LED chip 21 is disposed on the bottom surface of the concave portion 22a. A thin film made of a material having high light reflectivity, for example, silver or aluminum is formed on the inner peripheral surface of the recess 22a. The sealing material 23 is made of a translucent material that transmits light from the LED chip 21, for example, a transparent silicone resin, and preferably includes a diffusing material that diffuses light. The phosphor 24 is composed of a yellow phosphor such as a YAG phosphor that is excited by blue light from the LED chip 21 and emits yellow light having a main wavelength of 580 nm (see FIG. 7 described later). The first light source unit 2 emits white light by mixing the blue light from the LED chip 21 and the yellow light from the phosphor 24 with each other.

  As shown in FIG. 6B, the second light source unit 3 replaces the LED chip 21 with the LED chip 31 based on the first light source unit 2 shown in FIG. The body 24 is replaced with a phosphor 34. The LED chip 31 is composed of a near-ultraviolet LED chip that emits near-ultraviolet light having a main wavelength in a wavelength range of 290 to 380 nm. The phosphor 34 is formed of a phosphor that converts the wavelength of near-ultraviolet light emitted from the LED chip 31 into blue light having a dominant wavelength in the wavelength range of 475 to 485 nm. In addition, as shown in FIG.6 (c), the 2nd light source part 3 has the LED chip 32 which does not have a fluorescent substance and directly radiate | emits the blue light which has a main wavelength in a wavelength range 475-485 nm. It may be said.

  FIG. 7 shows the spectral distribution of white light emitted from the first light source unit 2 (white LED) (shown by a white diamond and a broken line), the first light source unit 2 and the second light source unit 3 (blue LED). ) Are combined at a luminous flux ratio of 1500: 300, showing the spectral distribution of irradiation light (indicated by a white circle and a solid line). When the first light source unit 2 and the second light source unit 3 are combined with this luminous flux ratio, the color temperature of the irradiated light is 7000K. Therefore, the color temperature of the irradiation light can be changed in the range of 5000K to 7000K by adjusting the luminous flux ratio between the first light source unit 2 and the second light source unit 3 in the range of 1500: 0 to 300.

  As shown in FIG. 8A, the irradiation light emitted from the lighting device 1 is controlled based on a light control toning curve that is defined so that the illuminance and the color temperature change in inverse correlation. The light control toning curve has a color temperature of 7000 K when the illuminance is 300 lx, a color temperature of 5000 K when the illuminance is 1500 lx, and the color temperature gradually changes according to the change in illuminance when the illuminance is low. Sometimes, it is specified that the color temperature changes rapidly according to the illuminance change. In this way, by logarithmically controlling the color temperature with respect to the illuminance, it is possible to realize natural irradiation light that makes it difficult for the user to feel uncomfortable as compared to the case where the color temperature is linearly controlled with respect to the illuminance (indicated by a dotted line). Can do. As shown in FIG. 8B, the light control toning curve is more preferably defined so that the logarithm control is performed in the range of 5,000 to 7000K and the color temperature in the range of 500 to 1000 lx.

  According to the illuminating device 1 configured as described above, since the color temperature decreases when the illuminance of the irradiation light is increased, the irradiation light is increased even if the illuminance of the irradiation light is increased in order to improve the readability of characters. This reduces the glare of the eyes and makes it difficult to feel tired eyes. Further, when the illuminance of the irradiation light is lowered, the color temperature is increased. Therefore, it is possible to save energy by reducing the illuminance while maintaining the legibility of characters. Furthermore, since the color temperature is controlled to approach 5000K, which has the highest LED light emission efficiency when the illumination light is set to a high illuminance, energy saving can also be achieved.

  Next, a lighting device according to a modification of the above embodiment will be described with reference to FIG. The illuminating device 1a is further provided with an elapsed time measuring unit 7 that measures the elapsed time since the first light source unit 2 and the second light source unit 3 are turned on based on the illuminating device 1 described above. . The control unit 4 includes the first light source unit 2 and the second light source unit so as to decrease the illuminance of the irradiation light and increase the color temperature of the irradiation light as the elapsed time counted by the elapsed time counting unit 7 increases. The output ratio with 3 is adjusted.

  In general, immediately after starting a visual task such as reading a character, the user tends to feel a sense of brightness due to the influence of illuminance rather than the color temperature of irradiation light. Therefore, in the lighting device 1a, immediately after the start of the visual operation, the irradiation light (see FIG. 4) having the highest LED light emission efficiency and the color temperature of 5000K is irradiated with high illuminance, for example, 1500 lx (condition of the point P in FIG. 3). . Then, as the elapsed time from turning on the first light source unit 2 and the second light source unit 3 increases, the illuminance of the irradiation light is changed so as to transition from the point P to the point Q and further to the point R. Increase color temperature while lowering. As a result, the illuminance can be lowered while maintaining a sense of readability, so energy saving can be achieved as compared with the case where the first light source unit 2 and the second light source unit 3 are kept on under the condition of the point P. You can plan.

  In addition, the illumination device according to the present invention is not limited to the above-described embodiment and its modifications, and various modifications can be made. For example, the first light source unit and the second light source unit are not necessarily configured by LEDs, and may be configured by a fluorescent lamp or an organic EL light emitting element. Further, the light emitted from each of the first light source unit and the second light source unit is not limited to white light and blue light, respectively, and may be, for example, daylight color light and light bulb color light.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 1st light source part 3 2nd light source part 4 Control part 7 Elapsed time timing part

Claims (4)

A first light source unit that emits light of a predetermined color temperature, a second light source unit that emits light of a color temperature different from that of the first light source unit, the first light source unit and the second light source A lighting unit including a control unit that performs dimming control of each unit,
Wherein the control unit, to the extent the illuminance of the illumination light color temperature 300~1500lx of 5000~7000K emitted from the illumination device, is changed to inverse correlation between intensity and color temperature, and illuminance at the time of low illuminance The output temperature ratio of the first light source unit and the second light source unit is adjusted so that the color temperature is gradually changed according to the change and the color temperature is rapidly changed according to the illuminance change at high illuminance. A lighting device.   2. The first light source unit includes a white LED that emits white light having a color temperature of 4500 to 5500K, and the second light source unit includes a blue LED that emits blue light. The lighting device described in 1.   The illumination device according to claim 1 or 2, wherein the control unit changes the illuminance of the irradiation light in a range of 500 to 1000 lx. An elapsed time timer that measures an elapsed time since the first light source unit and the second light source unit are turned on;
The control unit includes the first light source unit and the second light source unit so as to lower the illuminance of the irradiation light and increase the color temperature of the irradiation light as the elapsed time counted by the elapsed time counting unit increases. The lighting device according to any one of claims 1 to 3, wherein the output ratio of the lighting device is adjusted.

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