GB890039A - Improvements in particle size analyzer - Google Patents

Abstract

890,039. Counting-apparatus. ZEISS-STIFTUNG, CARL, [trading as ZEISS-C. [Firm of]]. Dec. 12, 1960 [Dec. 10, 1959 (2)], No. 42616/60. Class 106 (1). In apparatus for counting objects in categories according to size, the aperture of an adjustable iris diaphragm is projected on to the objects, counters are associated with contacts connected with the diaphragm setting member and mechanical means are provided for varying the width of the aperture intervals associated with the individual counters, further means being provided for ensuring that the distance between successive aperture intervals is zero. As described for counting objects into fortyeight size categories, forty-eight counters 3 are provided, together with a totalizing counter 4. An illuminated ground glass disc 6 has a central transparent part 7 and a transparent copy of a photograph of the objects is so laid on the ground glass disc that the object to be counted lies over the central part 7. Wheels 8, 9 are provided for manually adjusting the aperture of an iris diaphragm (not shown) and thus the size of the spot projected on the transparent part 7. When the spot coincides with the size of the object to be categorized, a foot pedal 12 is depressed, thereby stepping on the appropriate counter 3, rocking a lever 10 to mark the counted object with a pencil 11. The hand wheels 8, 9 are rigidly mounted on a shaft 13 carrying a commutator 65 having conducting portions 23, insulating portions 24 and sliding contacts 25, 26, 27, 28, Figs. 2 and 5. Mounted for axial movement on the shaft 13 is a sleeve 51 guided by a pin 54 in a groove 53 in the shaft 13. Fixed to the sleeve 51 is a worm gear 52 engaging a spirally-toothed gear which when rotated in response to rotation of the wheel 8 or 9, varies the aperture of an iris in a tube 19. Fixed to the sleeve 51 is a transmission member 56 which normally rolls on the front periphery of a hollow cylinder 57. However, by rotation of a knob 63 a cam 59 is moved axially and the transmission member 56 then rolls on the end of the cam 59 so that the shaft 51 is moved axially, the variation of the iris diameter thus being no longer in a linear relationship to the rotation of the handles 8, 9. The counters 3 are associated with fixed increments of hand wheel rotation so objects of a prescribed size range can be distributed into more or fewer catagories according to the development of the cam 59. In operation, the hand wheels 8, 9 are rotated to set the desired iris aperture, thereby rotating the commutator 65 and an auxiliary commutator 16. The foot switch 12 is then actuated to close switches 33, 34, Fig. 5, thereby actuating a magnetic brake 18, Figs. 2 and 5, to lock the hand wheels 8, 9. Assuming that the contact 25 is on an insulation gap 24, then the contact 17 is on a conducting portion on the commutator 16 so that a relay 39 is energized to operate switches 41, 42, thereby connecting in circuit the contacts 26, 28 which engage conducting portions 23. The switch 34 operates a relay 36 to pull down the marking lever 10 and close a switch 32, thereby energizing the counter coil 3 1 -3 48 connected between contacts 26, 28 and also the totalizing counter 4. If the contacts 25, 27 engage conducting portions, the relay 39 is not energized since the contact 17 engages an insulated part of the commutator 16. In a modification, instead of the two pairs 25, 27; 26, 28 of contacts one pair of contacts is provided (Fig. 6, not shown).