Combined light emitting discharge lamp and luminaire using...

Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium

Reexamination Certificate

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C313S483000, C313S486000, C313S487000

Reexamination Certificate

active

06445119

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a discharge lamp and a luminaire.
2. Description of the Prior Art
Currently, colors reproduced by a variety of light sources are evaluated quantitatively based on the color rendering index, which has been an established method for quantitative evaluation of colors. The color rendering index evaluates quantitatively how faithfully light of interest reproduces colors, compared with a reference light. Recently, however, more attention has been paid to how desirably colors are reproduced, apart from the faithful reproduction. It has become increasingly important to illuminate colors in our living space such as colors of human skin, food, plants, interior decorations and clothes desirably.
At the present, discharge lamps for general illumination having a relatively high correlated color temperature ranging from about 5000 K to about 7000 K are commonly used for main illumination in houses and stores. However, it is said that lamps with a low color temperature from about 2800 to 4500 K are more suitable to create a relaxed atmosphere in the illuminated space than lamps with a high color temperature. For this reason, a light source with a low color temperature is gaining its popularity gradually year by year in the field of illumination in houses and stores.
Furthermore, a lamp with a high color temperature is more dazzling than a lamp with a low color temperature when the light source is viewed directly. Moreover, an incandescent lamp for downlight tends to be used together with a lamp for main illumination as a recent approach for illumination in houses and stores. When a lamp with a high color temperature is used for main illumination and an incandescent lamp is used additionally, the difference in color between the lamp with a high color temperature and the incandescent lamp causes a sense of incongruity.
As described above, although lamps with a low color temperature are thought to be suitable to create a relaxed atmosphere, lamps in a conventional low color temperature range of about 3700 K or less are believed to pose a problem as to how colors look under the lamps. For example, such a lamp allows an object illuminated such as a new tatami mat to look yellowish like an old mat, or the skin of a Japanese person to look unnatural, even though the lamp has a high color rendering index so that it can reproduce colors faithfully and emits three lights of blue, green and red as main emission. Thus, the color of the object illuminated is not reproduced desirably. Furthermore, there is another problem in that a white object such as a paper or a white shirt does not look white, namely, the lamp cannot provide high perception of white. It is also said that a lamp in a conventional low temperature range cannot provide sufficient color identification because natural colors are not reproduced, and it is more difficult to distinguish similar colors under such a lamp.
SUMMARY OF THE INVENTION
Therefore, with the foregoing in mind, it is the object of the present invention to provide a discharge lamp and a luminaire primarily emitting combined lights in blue, green and red spectral regions that allows improved reproduction of natural colors of various colored objects, is not overly dazzling, and barely causes a sense of incongruity when used with an incandescent lamp.
In order to solve the above-described problems, a first discharge lamp of the present invention radiates visible light including the following lights combined: light having an emission peak in 400 to 490 nm wavelength range in a blue spectral region; light having an emission peak in a 500 to 550 nm wavelength range in a green spectral region; and light having with an emission peak in 600 to 670 nm wavelength range in a red spectral region. The color point of the combined light lies within a region common to the following regions: a region bounded by an ellipse with a color point (u, v)=(0.224, 0.330) as its center, a major axis of 0.056, a minor axis of 0.024, and an angle from the u axis of 20 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.224, 0.330) as its center, a major axis of 0.078, a minor axis of 0.014, and an angle from the u axis of 30 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.235, 0.335) as its center, a major axis of 0.060, a minor axis of 0.030, and an angle from the u axis of 30 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.225, 0.330) as its center, a major axis of 0.060, a minor axis of 0.018, and an angle from the u axis of 20 degrees in the CIE 1960 UCS diagram; and a region on a side of color temperature lower than an isotemperature line of a correlated color temperature of 3500 K.
This embodiment achieves a discharge lamp with a low color temperature primarily radiating combined lights in blue, green and red spectral regions that provides excellent color discrimination (identification) and is not overly dazzling.
The visible light radiated by this discharge lamp includes radiation of atoms or molecules exited by radiation or discharge from a phosphor.
A second discharge lamp of the present invention radiates visible light including the following lights combined: light having an emission peak in 400 to 490 nm wavelength range in a blue spectral region; light having an emission peak in a 500 to 550 nm wavelength range in a green spectral region; and light having with an emission peak in 600 to 670 nm wavelength range in a red spectral region. The color point of the combined light lies within a region bounded by lines connecting four color points (u, v)=(0.235, 0.342), (0.252, 0.345), (0.248, 0.338), and (0.239, 0.334) in the CIE 1960 UCS diagram.
This embodiment achieves a discharge lamp with a low color temperature primarily radiating combined lights in blue, green and red spectral regions that allows an illuminated white object to be perceived as white (i.e., provides excellent perception of white) and is not overly dazzling.
A third discharge lamp of the present invention radiates visible light including the following lights combined: light having an emission peak in 400 to 490 nm wavelength range in a blue spectral region; light having an emission peak in a 500 to 550 nm wavelength range in a green spectral region; and light having with an emission peak in 600 to 670 nm wavelength range in a red spectral region. The color point of the combined light lies within a region common to the following regions: a region bounded by an ellipse with a color point (u, v)=(0.224, 0.330) as its center, a major axis of 0.056, a minor axis of 0.024, and an angle from the u axis of 20 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.224, 0.330) as its center, a major axis of 0.078, a minor axis of 0.014, and an angle from the u axis of 30 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.235, 0.335) as its center, a major axis of 0.060, a minor axis of 0.030, and an angle from the u axis of 30 degrees in the CIE 1960 UCS diagram; a region bounded by an ellipse with a color point (u, v)=(0.225, 0.330) as its center, a major axis of 0.060, a minor axis of 0.018, and an angle from the u axis of 20 degrees in the CIE 1960 UCS diagram; and a region bounded by lines connecting four color points: (u, v)=(0.235, 0.342), (0.252, 0.345), (0.248, 0.338), and (0.239, 0.334) in the CIE 1960 UCS diagram.
This embodiment achieves a discharge lamp that has both of the advantages of the first and second discharge lamps.
In the first, second and third discharge lamps, the color point of the combined light preferably lies within a region on a side of color temperature lower than an isotemperature line of a correlated color temperature of 3400 K in the CIE 1960 UCS diagram.
This embodiment provides an advantage in that when the discharge lamp

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