News Column

"Standard Light Source and Measurement Method" in Patent Application Approval Process

September 3, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent application by the inventor OHKUBO, Kazuaki (Kusatsu-shi, JP), filed on January 23, 2014, was made available online on August 21, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application is assigned to Otsuka Electronics Co., Ltd.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present invention relates to a standard light source used for measuring optical characteristics such as total luminous flux of a light source and a measurement method with the use of the standard light source.

"Total luminous flux (lumen: lm) has conventionally been evaluated as one of optical characteristics of light sources and luminaires. For general measurement of total luminous flux, a standard light source of which value for total luminous flux has already been known (that is, calibrated in advance) is employed. More specifically, by comparing total luminous flux (or illuminance) measured in a state that a standard light source is turned on with total luminous flux (or illuminance) measured in a state that a light source which is a measurement target is turned on in the same measurement system (typically, an integrating sphere), a value for total luminous flux of the light source which is the measurement target is calculated.

"New light emitting devices such as LEDs (Light Emitting Diodes) and organic EL (Electro Luminescence) have recently widely been used. Such a light emitting device is different in luminous intensity distribution characteristics from conventional fluorescent lamps, incandescent lamps, and the like. With such a difference in luminous intensity distribution characteristics, a new standard light source suitable for measurement of total luminous flux, such as an LED or organic EL, has been proposed (for example, Suguru Irie et al., 'New 2.pi. Geometry Total Luminous Flux Standard Lamp,' 11-6, Papers Presented at 2011 (44th) Annual Conference of the Illuminating Engineering Institute of Japan (IEIJ), September 2011, and Kenji Godo et al., 'Development of Standard LED for Total Luminous Flux of High-Power LED,' 11-9, Papers Presented at 2011 (44th) Annual Conference of IEIJ, September 2011).

"The standard light sources proposed in the documents described above are premised on dedicated design in accordance with luminous intensity distribution characteristics of an LED. Such a standard light source has a more complicated structure, unlike a conventional bulb-type standard light source. In addition, since the standard light sources disclosed in the documents described above include a light source portion and an integrating sphere, a non-light-emitting structure is relatively large in the standard light source."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventor's summary information for this patent application: "The present invention was made in consideration of such circumstances, and an object thereof is to provide a novel standard light source with a more simplified construction, which is suitable for measurement of total luminous flux of a light source different in luminous intensity distribution characteristics from a conventional standard light source, and a measurement method with the use of that standard light source.

"A standard light source according to one aspect of the present invention includes a light emitting portion, a power feed portion electrically connected to the light emitting portion, and a restriction portion provided between the light emitting portion and the power feed portion, for restricting propagation of light radiated from the light emitting portion toward the power feed portion. A surface of the restriction portion on which light from the light emitting portion is incident is constructed for diffuse reflection.

"Preferably, a cross-sectional area of the restriction portion in a direction perpendicular to an optical axis passing through the light emitting portion and the power feed portion is designed in accordance with distribution of luminous intensity of the light emitting portion.

"Preferably, the restriction portion has a flat surface on which light from the light emitting portion is incident.

"Alternatively, preferably, the restriction portion has a concave surface on which light from the light emitting portion is incident.

"Preferably, the standard light source further includes a hood covering a surface of the restriction portion and a space including the light emitting portion.

"A measurement method according to another aspect of the present invention includes the steps of preparing a calibrated standard light source, attaching the standard light source to a measurement apparatus and measuring optical characteristics of the standard light source while it is turned on, attaching a light source which is a measurement target to the measurement apparatus and measuring optical characteristics of the light source which is the measurement target while it is turned on, and determining optical characteristics of the light source which is the measurement target based on the measured optical characteristics of the standard light source, the measured optical characteristics of the light source which is the measurement target, and optical characteristics valued for the standard light source. The standard light source includes a light emitting portion, a power feed portion electrically connected to the light emitting portion, and a restriction portion provided between the light emitting portion and the power feed portion, for restricting propagation of light radiated from the light emitting portion toward the power feed portion. A surface of the restriction portion on which light from the light emitting portion is incident is constructed for diffuse reflection.

"The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIGS. 1A and 1B are diagrams showing examples of measurement of luminous intensity distribution characteristics of commercially available LED light bulbs.

"FIGS. 2A to 2C are schematic diagrams showing systems of measurement of total luminous flux.

"FIGS. 3A and 3B are diagrams each showing one example of results of measurement of total luminous flux using a measurement system including an integrating sphere and a measurement system including an integrating hemisphere.

"FIGS. 4A and 4B are schematic diagrams for illustrating a standard light source according to a first embodiment.

"FIGS. 5A and 5B are schematic diagrams for illustrating a standard light source according to a second embodiment.

"FIG. 6 is a schematic diagram for illustrating a standard light source according to a third embodiment.

"FIG. 7 is a flowchart showing a processing procedure in measurement of total luminous flux for a sample light source including a standard light source according to the present embodiment."

URL and more information on this patent application, see: OHKUBO, Kazuaki. Standard Light Source and Measurement Method. Filed January 23, 2014 and posted August 21, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5144&p=103&f=G&l=50&d=PG01&S1=20140814.PD.&OS=PD/20140814&RS=PD/20140814

Keywords for this news article include: Otsuka Electronics Co. Ltd.

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Source: Electronics Newsweekly


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