Electric lamp and discharge devices – With luminescent solid or liquid material – With gaseous discharge medium
Reexamination Certificate
1999-03-23
2002-07-02
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
With gaseous discharge medium
C313S487000, C252S30140P
Reexamination Certificate
active
06414426
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a high efficiency illuminating light source which ensures such a level of color reproduction that allows categorical color perception for surface colors of at least red, green, blue, yellow white, and black on which categorical color perception of the human visual characteristics is based.
The invention relates to the following three major technologies.
The first is a fluorescent lamp and a metal halide lamp for providing high-efficiency illuminating light source which allows high luminous brightness in mesopic vision and scotopic vision or in wide visual field, while ensuring such a level of color reproduction that allows categorical color perception for surface colors of at least red, green, blue, yellow, white and black.
The second is a fluorescent lamp and a metal halide lamp for providing illumination which has whiteness in the light color without causing sense of incongruity when used in conjunction with a conventional high temperature light source, while ensuring such a level of color reproduction that allows categorical color perception for surface colors of at least red, green, blue, yellow, white and black.
The third is a fluorescent lamp and a metal halide lamp for providing high-efficiency illumination which has light color equivalent to incandescent lamp color without causing sense of incongruity when used in conjunction with a conventional low color temperature light source, while ensuring such a level of color reproduction that allows categorical color perception for surface colors of at least red, green, blue, yellow, white and black.
BACKGROUND ART
In conventional lamps, spectral characteristic has been designed by evaluating the subtle color reproduction quality in terms of general color rendering index (Ra) with reference to a reference light source (black body radiation, reconstituted daylight radiator). In contrast, a Japanese patent application (Application No. JAP-HEI 7-242863(Sep. 21, 1995), PCT/jp96/02618 based on said Japanese application, discloses a method of optimizing the design of spectral characteristic by applying such human visual characteristics that human recognizes color roughly (namely categorical color perception).
This method made it possible to provide high-efficiency light sources while ensuring such a level of color reproduction that allows categorical color perception for surface colors of at least red, green, blue, yellow, white and black on which categorical color perception of the human visual characteristics is based. A point of achieving the light source realizing categorical color perception with high-efficiency is to concentrate the wavelength of light into wavelength bands mainly of green and red. Such a light source will be called new high-efficiency light source hereinafter.
The new high-efficiency light source which is designed with preference placed on the light emission efficiency while satisfying the minimum requirement of color reproduction is often used for exterior lighting, load lighting, street lighting, etc. This is because exterior, road, street, etc. does not require high fidelity quality color reproduction which is required for interior lighting, with emphasis placed on the luminous efficacy of the light source.
And another point to realizing such new high-efficiency light source is to set the deviation from Planckian locus (Duv) to be 0 or positive on uv chromaticity coordinates.
The range where deviation from Planckian locus (Duv) is 0 or higher is the region which allows categorical color perception of the basic colors with high efficiency. Therefore, the new high-efficiency light source takes positive values of Duv as far as categorical color reproduction of the basic colors can be maintained. Now a portion which has not been utilized in the conventional light sources other than the new high-efficiency light source, in the range of positive Duv values will be described in detail below.
As an international standard related to the classification of chromaticity of illuminating light sources for describing the light source colors, IEC (International Electrotechnical Commission) standard has been used. Various countries of the world also have their own standards. One of these is the chromaticity classification standard for fluorescent lamps specified in JIS (Japanese Industrial Standards) used in Japan.
The IEC standard determines light colors in terms of tolerance with reference to a central point which is preset in the vicinity of the Planckian locus, while the JIS defines upper and lower limitation lines in the vicinity of the Planckian locus and specifies the inner region of the limitation lines as the tolerable region.
Conventional lamps have been developed with care not to allow the emission to deviate upward from the Planckian locus (positive side of Duv), from the viewpoint of evaluating the color rendering performance of the prior art.
In actuality, however, width of the tolerable range is from 7.5 to 9.5 in terms of Duv in the vertical direction in the case of the IEC, and from 10 to 19 in the case of JIS, and therefore illuminating light sources having light colors in a range from 0 to 5 of Duv on the positive side have been used in the prior art.
As a standard for describing the applicable range of light source in terms of white color from a different point of view, there is the CIE standard for signal light color. According to this standard, the region on the positive side of Duv out of a narrow white color region specified along the Planckian locus has not been utilized as illuminating light source of white light.
An object of the invention is to improve the impression of brightness in mesopic vision and scotopic vision of the new high-efficiency light source. It is known that, under photopic vision condition where the illuminance is high, cone cells among the visual cells work, and under scotopic vision where the illuminance is low, rod cells among the visual cells work, while under mesopic vision where the illuminance is at the intermediate level between the above two, both cone cells and rod cells work. However, spectral characteristic of conventional illuminating light sources has been designed assuming photopic vision wherein cone cells work.
In a situation where the new high-efficiency light source is used, instead of a conventional light source designed for exact color reproduction, on the other hand, the illumination is designed with relatively low illuminance (scotopic vision, mesopic vision).
Therefore, it is the first object of the invention to design the spectral characteristic by placing emphasis on a condition of relatively low illuminance while taking into consideration the effect of the rod cells for the new high-efficiency light source.
Second object of the invention is to improve the impression of brightness in wide visual field of the new high-efficiency light source.
While illuminance and luminance are used as the photometric quantities of brightness, spectral characteristic of illuminance and luminance are based on the spectral characteristic of brightness measured in a visual angle of 2° in the fovea centralis of the eye. However, because the eye receives light not only from a range limited around the fovea centralis but also from a wider visual field in the actual illumination environment, there have been such cases that actual impression of brightness is different from the illuminance, depending on the spectral distribution of the light source.
Thus the second object of the invention is to set such spectral characteristic of the new high-efficiency light source that improves the impression of brightness in a wide field of view which is felt when entering an actual illumination environment.
Third object of the invention is to improve the whiteness of light color of the new high-efficiency light source. The whiteness of the new high-efficiency light source is poor.
Hence the invention aims to improve the whiteness of the new high-efficiency light source as the third object.
Fourth object of the invention is to provide incandes
Akashi Izumi
Sakamoto Shoetsu
Shimizu Masanori
Matsushita Electric - Industrial Co., Ltd.
Patel Ashok
Ratner & Prestia
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