GB918319A - Reading device on a balance - Google Patents

Abstract

918,319. Weighing. METTLER, E., [trading as METTLER, FABRIK FUR ANALYSENWAAGEN, E.]. March 15, 1961 [Oct. 26, 1960], No. 9543/61. Class 143. A glass plate 15 is fixed to the end of the weigh beam 10 and moves in an arc through a distance according to the weight in the pan. The plate is calibrated in figures representing whole numbers, with graduation lines to correspond. A light beam from a lamp 18, directed by a lens 19, projects an optical image of the calibrations, through a magnifying lens 20 and by way of a deviating prism 21, on to the plane face of a planar-convex (or planar-parallel) collecting lens 22. As the beam is directed towards the lens 22 it passes through a glass plate 24 which is mounted in a holder 25 in which are recesses 28, 29 entered by pins 26, 27 whereby it may be tilted. The tilting mechanism comprises a cam 34 on a shaft 33 which is rotatable, through gearing, by a knob 30 and a pin 36 projects from the holder 25 and engages the cam 34. Fixed to the shaft 33 is a glass disc 38, a surface of which faces close to the plane face of the lens 22 and is calibrated in figures representing decimal numbers. At the place on the plane face of the lens 22 where the magnified image of a graduation line appears, the lens face has a mark in the form of two slightly spaced triangles. This mark 23, the magnified image 16<SP>1</SP> of the whole numbers, the magnified image 17<SP>1</SP> of the graduations, and the decimal numbers 39, on the dies 38, then appear as in Fig. 4, which shows the total image as would be seen when looking through the glass disc 38 in the direction of the lens 22. The image is further magnified, and also spread, by an optical system comprising a rhombic prism 42 and lenses 43, 44. The optical rays corresponding to the numbers 16<SP>1</SP> are diverted through the prism 42, magnified by the lens 43 and projected on to a ground glass screen 40 to form an image 16<SP>11</SP>, Fig. 5. The numbers 39, graduations 17<SP>1</SP> and mark 23 are magnified by the lens 44 and projected to form images 39<SP>1</SP>, 1711 and 23<SP>1</SP>. A cover 45 on the screen 40 has three windows which cause the image to show up as shown in Fig. 5. Alternatively the cones could be on the lens 22. The whole number of the weight is read off in the left-hand window, as seen in Fig. 5, and the decimal number of the weight is precisely determined by tilting the lens 22, through operation of the knob 30, till the corresponding graduation appears in the space between the two triangles 23<SP>1</SP> of the magnified image of the mark 23, the operation of tilting the lens also causing the dies 38 to rotate and bring the image of the decimal figure carried by it into the right-hand window as seen in Fig. 5. The device may be simplified by omitting the prism 42 and lens 43 and arranging the calibrations to give the required spread of the images.