HOME

TheInfoList



OR:

Super-LumiNova is a brand name under which strontium aluminate–based non-
radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
and nontoxic
photoluminescent Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. ph ...
or afterglow
pigments A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...
for illuminating markings on watch dials, hands and bezels, etc. in the dark are marketed. When activated with a suitable
dopant A dopant (also called a doping agent) is a small amount of a substance added to a material to alter its physical properties, such as electrical or optics, optical properties. The amount of dopant is typically very low compared to the material b ...
(
Europium Europium is a chemical element; it has symbol Eu and atomic number 63. It is a silvery-white metal of the lanthanide series that reacts readily with air to form a dark oxide coating. Europium is the most chemically reactive, least dense, and soft ...
and
Dysprosium Dysprosium is a chemical element; it has symbol Dy and atomic number 66. It is a rare-earth element in the lanthanide series with a metallic silver luster. Dysprosium is never found in nature as a free element, though, like other lanthanides, it ...
), it acts as a
photoluminescent Photoluminescence (abbreviated as PL) is light emission from any form of matter after the absorption of photons (electromagnetic radiation). It is one of many forms of luminescence (light emission) and is initiated by photoexcitation (i.e. ph ...
phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...
with long persistence of
phosphorescence Phosphorescence is a type of photoluminescence related to fluorescence. When exposed to light (radiation) of a shorter wavelength, a phosphorescent substance will glow, absorbing the light and reemitting it at a longer wavelength. Unlike fluor ...
. This technology offers up to ten times higher brightness than previous
zinc sulfide Zinc sulfide (or zinc sulphide) is an inorganic compound with the chemical formula of ZnS. This is the main form of zinc found in nature, where it mainly occurs as the mineral sphalerite. Although this mineral is usually black because of various i ...
–based materials. These types of phosphorescent pigments, often called lume, operate like a rechargeable light battery. After sufficient activation by sunlight, fluorescent, LED, UV (blacklight), incandescent and other light sources, they glow in the dark for hours. Electrons within the pigment are being "excited" by
ultraviolet Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight and constitutes about 10% of ...
light exposure—the excitation wavelengths for strontium aluminate range from 200 to 450 nm
electromagnetic radiation In physics, electromagnetic radiation (EMR) is a self-propagating wave of the electromagnetic field that carries momentum and radiant energy through space. It encompasses a broad spectrum, classified by frequency or its inverse, wavelength ...
—to a higher energetic state and after the excitation source is removed, fall back to their normal energetic state by releasing the energy loss as visible light over a period of time. Although fading over time, appropriately thick applicated larger markings remain visible for dark adapted human eyes for the whole night. This Ultraviolet light exposure induced activation and subsequent light emission process can be repeated again and again.


History

Nemoto & Co., Ltd. – a global manufacturer of phosphorescent pigments and other specialized phosphors – was founded by Kenzo Nemoto in December 1941 as a luminous paint processing company and has supplied and developed luminous paint to the watch and clock and aviation instruments industry since. Super-LumiNova is based on LumiNova branded pigments, invented in 1993 by the Nemoto staff members Yoshihiko Murayama, Nobuyoshi Takeuchi, Yasumitsu Aoki and Takashi Matsuzawa as a safe replacement for
radium Radium is a chemical element; it has chemical symbol, symbol Ra and atomic number 88. It is the sixth element in alkaline earth metal, group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, ...
-based
luminous paint Luminous paint (or luminescent paint) is paint that emits visible light through fluorescence, phosphorescence, or radioluminescence. Fluorescent paint Fluorescent paints 'glow' when exposed to short-wave ultraviolet (UV) radiation. These UV ...
s. The invention was patented in 1994 by Nemoto & Co., Ltd. and licensed to other manufacturers and watch brands. In 1998 Nemoto & Co. established a join-venture with RC Tritec AG called LumiNova AG, Switzerland to manufacture 100 percent Swiss made afterglow pigments branded as Super-LumiNova. After that, the production of radioactive luminous compounds by RC Tritec AG was completely stopped. According to RC Tritec AG the Swiss watch brands all use their Super-LumiNova pigments.


Color variations and grades

Over time, RC Tritec AG developed other afterglow color variations than the original Nemoto & Co. C3 green and higher grades of afterglow pigments. Any other Super-LumiNova emission color offering than C3 is achieved by adding colorants that adsorb light and hence limit the amount of light the afterglow pigment can absorb and emit. After the green glowing and pale yellow-green in daylight appearing C3 (emission at 515 nm) variant, the blue-green glowing and in daylight white appearing BGW9 (emission at 485 nm, close to the
turquoise Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula . It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its hue. The robi ...
wavelength) color variant is the second most effective variant regarding pure afterglow brightness. Different colors can however be chosen to optimize (perceived) light emission, dictated by the human eye
luminous efficiency function A luminous efficiency function or luminosity function represents the average spectral sensitivity of human visual perception of light. It is based on subjective judgements of which of a pair of different-colored lights is brighter, to describe re ...
variance. Maximal light emission around
wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...
s of 555 nm (
green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...
) is important for obtaining optimal
photopic vision Photopic vision is the vision of the eye under well-lit conditions (luminance levels from 10 to 108  cd/m2). In humans and many other animals, photopic vision allows color perception, mediated by cone cells, and a significantly higher vis ...
using the eye
cone cell Cone cells or cones are photoreceptor cells in the retina of the vertebrate eye. Cones are active in daylight conditions and enable photopic vision, as opposed to rod cells, which are active in dim light and enable scotopic vision. Most v ...
s for observation in – or just coming from – well-lit conditions. Maximal light emission around wavelengths of 498 nm (
cyan Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK c ...
) is important for obtaining optimal
scotopic vision In the study of visual perception, scotopic vision (or scotopia) is the vision of the eye under low-light conditions. The term comes from the Greek ''skotos'', meaning 'darkness', and ''-opia'', meaning 'a condition of sight'. In the human eye, c ...
using the eye
rod cell Rod cells are photoreceptor cells in the retina of the eye that can function in lower light better than the other type of visual photoreceptor, cone cells. Rods are usually found concentrated at the outer edges of the retina and are used in ...
s for observation in low-light conditions. Besides technical and human eye dictated reasons, esthetic or other reasons can also influence Super-LumiNova color choices. Super-LumiNova is offered in three grade levels; Standard, A and X1. The initial brightness of these grades does not significantly vary, but the light intensity decay over time of the A and X1 grades is significantly reduced. This means the X1 grade takes the longest to become too dim to be useful for the human eye. Not all Super-LumiNova color variations are available in three grades. Super-Luminova technology has the introduction of Grade X2, enhancing watch readability in low-light conditions.


Stability

Due to the fact that no chemical change occurs after a charge-discharge cycle, the pigments theoretically retain their afterglow properties indefinitely. A reduction in light intensity only occurs very slowly, almost imperceptibly. This reduction increases with the degree of coloring of the pigments. Intensely colored types lose their intensity more quickly than neutral ones. High temperatures of up to several hundred degrees Celsius are not a problem. The only thing that needs to be avoided is prolonged contact with water or high humidity, as this creates a hydroxide layer that negatively affects the light emission intensity.report on www.info-uhren.de
(PDF; 37 kB)


Uses

Besides being used in timepieces by industry and hobbyists, Super-LumiNova is also marketed for application on: * Instruments: scales, dials, markings, indicators, etc. * Scales: engravings, silkscreen-printing * Aviation instruments and markings * Jewelry * Safety- and emergency panels, signs, markings * Aiming posts * Various other parts


Application methods

Super-LumiNova granulated pigments are applied either by manual application,
screen printing Screen printing is a printing technique where a mesh is used to transfer ink (or dye) onto a substrate, except in areas made impermeable to the ink by a blocking stencil. A blade or squeegee is moved across the screen in a "flood stroke ...
or
pad printing Pad printing (also called tampography) is a printing process that can transfer a 2-D image onto a 3-D object (e.g., a ceramic pottery). This is accomplished using an indirect offset (gravure) printing process that involves an image being transf ...
. RC Tritec AG recommends up to application thickness in one or multiple layer(s). Over that, the ultraviolet light starts getting problems to effectively reach and activate the bottom of the deposited pigment, diminishing the returns for additional application thickness. The pigments and binders are produced separately, as there is no optimal binder for differing applications. This forces RC Tritec AG to offer many solvent and non-solvent based binder systems to maximally concentrate the granulated pigments in the mixture for application on various surfaces. Alternatively, RC Tritec AG offers Lumicast pieces, which are highly concentrated luminous Super-LumiNova 3D-castings. According to RC Tritec AG these ceramic parts can be made in any customer desired shape and result in a higher light emission brightness when compared to the common application methods. Lumicast pieces can be glued or form fitted on various surfaces.


Alternative for afterglow pigments

By the late 1960s,
radium Radium is a chemical element; it has chemical symbol, symbol Ra and atomic number 88. It is the sixth element in alkaline earth metal, group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, ...
was phased out and replaced with safer alternatives. Tritium was used on and the original Panerai Luminor dive watch Radiomir and almost all Swiss watches from 1960 to 1998 when it was banned. Tritium-based substances ceased to be used by
Omega SA Omega SA is a Swiss luxury watchmaker based in Biel/Bienne, Switzerland. Founded by Louis Brandt in La Chaux-de-Fonds in 1848, the company formerly operated as ''Louis Brandt et Fils'' until incorporating the name ''Omega'' in 1903, becoming ' ...
in 1997. In the 21st century, one radioluminescent alternative for afterglow pigments requiring radiation protection is being produced and used for watches and other uses. These are
tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...
-based devices called "gaseous tritium light source" ( GTLS). GTLS are made using sturdy (often glass) containers internally coated with a
phosphor A phosphor is a substance that exhibits the phenomenon of luminescence; it emits light when exposed to some type of radiant energy. The term is used both for fluorescent or phosphorescent substances which glow on exposure to ultraviolet or ...
layer and filled with
tritium Tritium () or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with a half-life of ~12.33 years. The tritium nucleus (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of the ...
gas before the containers are permanently sealed. They have the advantage of being self-powered and producing a consistent luminosity that does not gradually fade during the night. However, GTLS contain radioactive tritium gas that has a
half-life Half-life is a mathematical and scientific description of exponential or gradual decay. Half-life, half life or halflife may also refer to: Film * Half-Life (film), ''Half-Life'' (film), a 2008 independent film by Jennifer Phang * ''Half Life: ...
of slightly over 12.3 years. Additionally, phosphor degradation will cause the brightness of a tritium container to drop by more during that period. The more tritium that is initially inserted in the container, the brighter it is to begin with, and the longer its useful life. This means the intensity of the tritium-powered light source will slowly fade, generally becoming too dim to be useful for dark adapted human eyes after 20 to 30 years.


See also

* Lumibrite — different named strontium aluminate–based phosphorescent pigments *
Radium dial Radium is a chemical element; it has symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is silvery-white, but it readily reacts with nitrogen (r ...


References

{{Reflist, 2


External links


Technical Features Superluminova
- Archived fro
the original





All About Super-LumiNova
Luminescence Horology