Technology
Electronic balances spark technology race The firm also has interface cards for use with customers' own printers, models growing; features programable calculators, and computers. Programable calculators can include improved interfacing convert grams to other units, determine numbers of small parts in conwith data-handling systems, tainers, calculate density or volume, or perform statistical analyses on a special functions built-in number of weighings. Users can select a time-averaged mode to weigh live, moving animals or to use in breezy or A fast-growing U.S. and worldwide vibrating environments. market for electronic, top-loading, On the four Ohaus dual-range balprecision balances has set off a tech- ances, the finer range is available for nology race among manufacturers only the first tenth of total capacity. jockeying for position. Ohaus Scale Thus, on the 3000-g balance, only the Corp., based in Florham Park, N.J., first 300 g on the pan can be weighed has just expanded its first line of such to 0.01 g, and higher weights are acbalances (C&EN, Dec. 4,1978, page curate only to 0.1 g. 5) from three to seven. The line has a At Mettler, which is the U.S. subrange of capacities designed to meet sidiary of Mettler Instrumente, of 85% of needs for this type of balance, Greifensee, Switzerland, the second, and has improved capabilities for in- finer range was made movable over terfacing with printers, programable the entire balance capacity. Thus, calculators, and computers. after setting a beaker on a 400-g balShimadzu Scientific Instruments ance, the user can tare to zero, select entered the U.S. market in February the finer weighing mode, and weigh with a line of 18 such balances. Two the next 40 g added to 0.001 g accuother balance makers, Mettler In- racy. Sartorius has since added this strument and West Germany's Sar- floating second-range feature to its torius-Werke, have expanded their balances. lines in the past three years and made Development of dual-range baltechnological improvements. ances has been a partial response to Precision balances weigh rapidly the need of many users for a single and accurately on a routine basis. balance that weighs an order of magTypical capacities range from 300 g, nitude more accurately than existing accurate to 0.01 g, to 5000 g, accurate technology can provide over its entire to 0.1 g. Many of these have a second, capacity range. Current technology is smaller capacity range accurate to limited by lack of linearity of maganother decimal place. Electronic netic field strength in these balances, precision balances are replacing older, which work on the principle of magmechanical balances in laboratories, netic force restoration. colleges, and high schools. New apIn this principle, a weight on a plications also are opening up in balance pan forces a mass of metal production line quality control. down into the field of a permanent The U.S. market is about 25,000 magnet. The balance electronics rebalances per year—worth almost $40 spond with a current applied to an million—and growing at up to 10% electromagnet, which repels the metal annually. Although sales of replace- mass until the balance again reaches ment balances may be nearing satu- a null point. The needed current is ration in the U.S., there is still un- translated into a digital signal, which, tapped potential in other countries in turn, is converted to weight and where 60 to 80% of balance sales are provides a signal usable by accessory for replacement. Industry observers data-handling units. estimate that Mettler has 50% of U.S. Such factors as temperature and sales of electronic precision balances, humidity affect linearity of magnetic Sartorius 30%, Ohaus 10%, and half a field strength, limiting accuracy over dozen other firms 10%. the entire capacity range. Continued Ohaus has adopted a single circuit research at major manufacturers is board for all seven current models, expected to overcome this limitation making them easier to manufacture. and result in balances that weigh an Number of "smart" balance
order of magnitude more accurately than today. Sartorius, whose balances are marketed in the U.S. by Brinkmann Instruments, eliminated the need for costly, all-purpose, programable calculators in 1977 by developing lower-cost, factory-programed, dedicated modules for such special functions as unit conversion, piece counting, density and volume determination, time averaging, and statistical analysis. Mettler followed this approach soon after. In addition to lower cost, the simplicity of preprogramed modules allows use of balances by less well-trained persons. Shimadzu Scientific Instruments, the U.S. subsidiary of Japan's Shimadzu Corp., has met the need for special functions by offering not only simple balances, but balances dedicated to single, special functions and multipurpose balances whose special functions, memories, and other features of a programable calculator are built in and selectable by buttons on the front. Even simple Shimadzu balances are versatile, though, because microswitches on the backs activate automatic printing and zeroing, time-averaged weighing, and memory. These standard features are options on other balances. Shimadzu has several dual-range balances, but as with Ohaus balances, only the first tenth of balance capacity can be selected to weigh in the finer range. Such sophisticated applications as those in laboratories or on packaging or production lines will need careful attention to the accuracy required at a given capacity and the ease of interfacing with a data processing system. For the less-demanding needs of high school and university instruction, users will find that competition has heated up in price as well. The 1976 introduction of the first Ohaus balances came at a time of weakness in the dollar. Balances made in the U.S. thus competed well with imported ones, whose prices are pegged to values of the German mark and Swiss franc. With the strengthening of the dollar against those currencies that began in 1980, European manufacturers were able to lower U.S. prices in increments that total about 10% to date. Steve Stinson, New York Aug. 17, 1981 C&EN
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