GB752542A - Improvements in and relating to precision balances such as analytical balances - Google Patents

Abstract

752,542. Weighing apparatus. CLESS, O. E. Oct. 26, 1954 [Oct. 29, 1953], No. 30820/54. Class 143 A balance has its deflection indicated by the optical projection of a micro-scale on to a screen which carries a 100 division comparison scale, operating similarly to a vernier scale, to allow weighing to 4 places of decimals, there being only one dividing line of the micro-scale visible on the comparison scale at any instant. The pointer 24 (Fig. 1), attached to beam 22, carries a micro-scale 1, with dividing lines 10 (Fig. 2), whose image is projected, by lens 4 and mirrors (or prisms) 5 and 6, on to an opaque ground glass screen 7, having a, window 9 and a comparison scale 8 (Fig. 3), with transparent numerals and dividing lines. Transparent numerals 11 (Fig. 2), on scale 1, give the tens and hundreds of milligrams in window 9, while transparent recesses 12 allow one numeral of the vertical row on scale 8 to be wholly visible and give the unit milligrams. The one dividing line of scale 1 visible on scale 8 gives the tenths of a milligram at the point where it falls between two of the black squares of the comparison scale 8. A transparent window 13 may be provided in which higher weight values laid on automatically or by hand are indicated; in the former case, a knob external to the casing allows positioning of the weight on the balance arm, and a corresponding indication in the window.