Värifosforiyksikkö

Värifosforiyksikkö (color phosphor unit) is a proposed, non-SI unit used to describe the color-performance of phosphor materials in display and lighting technologies. It is not an officially adopted standard, and its exact definition varies between sources. In practice, the term is used to capture both the brightness and the color quality produced by a phosphor layer under specified input conditions.

Definitions of the unit are not uniform. A common interpretation treats värifosforiyksikkö as a measure of luminous flux per unit area emitted by a phosphor layer per unit of input radiant power, weighted by the human eye’s luminance sensitivity (the V(λ) function). Under this approach the unit resembles a luminance- or efficacy-related quantity that combines output brightness with efficiency. An alternative definition uses the emitted spectral power distribution to derive chromaticity coordinates, color rendering potential, and related perceptual attributes, yielding a more color-centric characterization.

Measurement typically requires standardized test conditions: a known input power or current to the phosphor material, a calibrated measurement of the emitted spectrum, and, if needed, a calculation of luminous flux using the CIE V(λ) function. Normalization to the phosphor area is common to enable comparisons across samples.

Relation to established quantities is informal; värifosforiyksikkö is related to luminous efficacy (lm/W), luminance, spectral power distribution, and color-quality metrics like CIE chromaticity coordinates, CRI, and CCT, but it is not a formal SI-derived quantity.

Use of the term appears mainly in Finnish technical discussions and research contexts. When used, it should be accompanied by a clear definition of the specific test conditions. See also color phosphor, phosphor-conversion LEDs, luminous efficiency.