Electric lamp and discharge devices: systems – With radiant energy sensitive control means
Reexamination Certificate
1999-10-04
2001-09-04
Vu, David (Department: 2821)
Electric lamp and discharge devices: systems
With radiant energy sensitive control means
C315S158000, C315S159000, C315SDIG004
Reexamination Certificate
active
06285134
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light irradiation method and a light irradiation system for increasing or decreasing a perceived brightness of a target, which is illuminated, by performing time-wise control of prescribed illumination light.
2. Description of the Related Art
Various illumination methods for increasing a brightness perceived regarding an illuminated target (hereinafter, referred to as, for example, a “perceived brightness of a target”) have been studied. From a practical point of view, the entirety of the inside of a room is set as a target, and researches on methods for increasing the perceived brightness of a target are performed.
According to one of the methods developed so far, walls of the room are illuminated to be brighter than the rest of the room, instead of uniformly illuminating the entirety of the inside of the room. Thus, the entirety of the inside of the room is perceived to be brighter at an equal energy consumption. According to another method developed so far, a painting on the wall or a table in the room is spot-illuminated. Thus, the inside of the room is perceived to be brighter. Furthermore, according to the method recently proposed in Japanese Laid-Open Publication No. 8-279306, a “sparkling” light emitting section which is small in size but has a high luminance is included in an illumination device, so that the inside of the room is perceived to be brighter.
Regarding a target located indoors, for example, K. Hashimoto et al., “Visual Clarity and Feeling of Contrast”, Color Res. Appl., Vol. 19-3, pp. 171-185 (1994) and K. Hashimbto et al., “Method for evaluating the color rendering property of a light source based on the consciousness”, the Journal of the Illuminating Engineering Institute of Japan, Vol. 79, No. 11, pp. 29-37 (1995) describe that a perceived brightness of an indoor target can be raised by utilizing the phenomenon that the colorfulness of a target is increased when illuminated with a lamp having a superior color rendering property.
In a recent study performed by Ikeda et al., information obtained from various objects seen by an observer when he/she enters the room is referred to as “initial visual information”, and illumination states of the inside of the room recognized based on the initial visual information including the brightness of the room is referred to as“illumination recognition visual space”. Ikeda et al. has studied physical factors which determine the initial visual information and the illumination recognition visual space. As a result, it is reported that when two rooms which are different only in the brightness (reflectance) of the walls are located side by side and illuminated under the same conditions, the tone of gray color is perceived to be brighter in the room having a brighter wall (having a wall of a higher reflectance) than in the other room (Mizogami et al., “Apparent brightness based on the concept of the illumination recognition visual space”, the Proceedings of the 31st (1998) Annual Conference of the Illuminating Engineering Institute of Japan, 136, page 227 (1998)).
The above-mentioned studies indicate that a perceived brightness of the target can be increased under various conditions without increasing the amount of light directly illuminating the target.
However, the above-mentioned conventional methods are all for increasing a perceived brightness of a target. Conventionally, no method for effectively decreasing a perceived brightness of a target by performing time-wise control of light intensity without changing the amount of light directly illuminating the target has been utilized. For this reason, the conventional art has not succeeded in effectively changing (increasing and decreasing) a perceived brightness of a target.
SUMMARY OF THE INVENTION
In accordance with a light irradiation method of the present invention, a main irradiation section forming a target and a sub irradiation section for providing sub illumination light to or from at least one of a background and a neighborhood of the target are provided, and a perceived brightness of the target is varied by performing time-wise control of an intensity of the sub illumination light emitted by the sub irradiation section.
In one embodiment, the main irradiation section is an illumination source for emitting main illumination light.
Specifically, a perceived brightness of the illumination source is decreased by increasing the intensity of the sub illumination light emitted by the sub irradiation section, and a perceived brightness of the illumination source is increased by decreasing the intensity of the sub illumination light emitted by the sub irradiation section.
The time-wise control of the intensity of the sub illumination light may be performed so that a rate of change of the intensity is lower while the intensity is increasing than while the intensity is decreasing.
In one embodiment, the main irradiation section is an indication lamp for emitting a prescribed indication light.
Specifically, a perceived brightness of the indication lamp is decreased by increasing the intensity of the sub illumination light emitted by the sub irradiation section, and a perceived brightness of the indication lamp is increased by decreasing the intensity of the sub illumination light emitted by the sub irradiation section.
The time-wise control of the intensity of the sub illumination light may be performed so that a rate of change of the intensity is lower while the intensity is increasing than while the intensity is decreasing.
In one embodiment, the main irradiation section is an image display section for displaying a prescribed image, and the target is the prescribed image.
Specifically, a perceived brightness of the prescribed image is increased by increasing the intensity of the sub illumination light emitted by the sub irradiation section, and a perceived brightness of the prescribed image is decreased by decreasing the intensity of the sub illumination light emitted by the sub irradiation section.
Preferably, the prescribed image includes a content, a brightness of which is inherently changeable.
Preferably, a highest luminance of the sub illumination light is set to be equal to or less than a highest luminance of the target.
The intensity of the sub illumination light may be increased and decreased repeatedly.
The intensity of the sub illumination light may be varied in accordance with a sine waveform having a frequency of about 0.01 Hz or more and about 8 Hz or less.
Preferably, a minimum value of the intensity of the sub illumination light is larger than zero.
Preferably, the sub irradiation section is located at such a position that prevents an observer from viewing the sub irradiation section.
Thus, the invention described herein makes possible the advantages of providing an illumination method for effectively changing (increasing and decreasing) a perceived brightness of a target by changing illumination conditions of the background or the neighborhood of the target without changing the amount of light directly illuminating the target.
These and other advantages of the present invention will become apparent to those skilled in the art upon reading and understanding the following detailed description with reference to the accompanying figures.
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Tiller et al., “Perceived Room Brightness: Pilot Study on the Effect of Luminance Distribution,” 1995, vol. 27, No. 2.
Roufs et al., “Global Brightness Contrast and the Effect on Perceptual Image Quality,” 1994, vol. 2179.
European Search Report, application No. 9911914
Akashi Yukio
Yano Tadashi
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
Vu David
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