Compositions – Organic luminescent material containing compositions
Patent
1995-11-17
1999-08-03
Koslow, Melissa
Compositions
Organic luminescent material containing compositions
2523014R, 25230135, 25230136, 106 3115, 106 3164, 283 91, 283 92, 283 71, C09K 1106, C09K 1160, G06K 710
Patent
active
059321393
DESCRIPTION:
BRIEF SUMMARY
FIELD OF TECHNOLOGY
The present invention relates to a fluorescent substance excellent in light emission, a method of preparing the fluorescent substance, a fluorescent composition such as, for example, an inking medium for use in an ink jet printer, containing the fluorescent substance, a fluorescent mark carrier such as, for example, postal envelopes, postal cards or postal parcels having a fluorescent mark formed by printing the fluorescent composition, and an optical reader and an optical reading system both operable to optically read the fluorescent mark at a high speed.
BACKGROUND ART
In various fields of industries including the distribution industry, bar codes are widely utilized to control the physical distribution of commodities. The bar codes are also utilized having been printed on various cards such as, for example, pre-paid cards, commutation cards and data cards. These bar codes are read by an optical reader such as, for example, an optical scanner which subsequently processes information represented by the bar codes. Most bar codes carried by surfaces of commodities or cards are in the form of a pattern of stripes printed by the use of a black inking medium against a white background and visible to human eyes under visible rays of light. This visible mark is printed directly on merchandise or printed on a shaped sheet-like carrier which is in turn affixed to merchandise.
On the other hand, attempts have been made to form a mark such as a bar code by the use of a fluorescent substance capable of emitting an infrared region of light so that the fluorescent mark can be identified by an optical reader. While the fluorescent mark is generally invisible to the human eyes, the fluorescent mark emits a fluorescent light when the fluorescent substance contained therein is excited upon irradiation of an external light of a particular wavelength and, therefore, by analyzing the fluorescent light with an optical reader, information represented by the fluorescent mark can be decoded or identified. Even the fluorescent mark is, as is the case with the visible mark, printed directly on merchandise or printed on a shaped sheet-like carrier which is in turn affixed to merchandise.
As compared with the system in which change in intensity of light reflected from the visible mark is read in handling merchandise, a system for handling merchandise, including an optical reader for reading the fluorescent mark, has numerous advantages, some of which are listed below. color of the merchandise and, therefore, the reliability in reading the fluorescent mark is high with the reading error minimized. dirty, infrared rays of light emitted from the fluorescent mark has such a long wavelength that the reading error would seldom occur and the reliability is therefore high. visible rays of light, printing of the fluorescent mark on the merchandise will bring no adverse effect on the aesthetic appearance of the merchandise. light that no one can recognize the presence of the fluorescent substance, it can provide security of information.
Particulars of interest in this connection are disclosed in, for example, the Japanese Patent Publications No. 55-33837, No. 60-29996 and No. 62-24024.
The fluorescent mark discussed above is formed by printing a fluorescent inking medium containing a fluorescent substance on a carrier such as, for example, a surface of the merchandise in a predetermined pattern. An infrared fluorescent inking medium has long been known and is disclosed in, for example, the U.S. Pat. No. 4,202,491. The infrared fluorescent inking medium disclosed therein is prepared from an inorganic fluorescent substance containing one or a mixture of neodymium (Nd), ytterbium (Yb) and erbium (Er). The inorganic fluorescent substance which utilizes Nd as an optically active element is known to emit a fluorescent light having a maximum intensity at about 1,050 nm in wavelength when irradiated with an exciting light of 800 nm emitted by a GaAlAs light emitting diode. The inorganic fluorescent substance containing a mixture
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Kamoto Takanori
Nabeshima Tomio
Oshima Toshio
Saibara Shoji
Yamada Yukinori
Hitachi Maxell Ltd.
Koslow Melissa
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