Patent GB-742051-A (GB)
Title: Improvements in or relating to method and apparatus for determining the volume, weight, density or transit charge of objects and packages
IPC: G06G7/48
Filed: 1951-12-14
Abstract: 742,051. Electric analogue calculating systems. CONTINENTAL SILVER CO., Inc. Dec. 14, 1951 [Dec. 21, 1950; March 28, 1951; Aug. 18, 1951], No. 29335/51. Class 37. [Also in Groups XXXVII and XXXVIII] In apparatus for determining the volume, weight, density, and transit charge for a package, the latter is weighed on a platform spring balance selecting a resistance value passing a current logarithmically dependent on the weight, while sliders are manually adjustable to contact three sides of the package to select other values of resistance respectively passing currents logarithmically dependent on the corresponding dimensions so that the combined value of the total currents in the parallelled resistances represents the logarithm of the package volume, and a rotary timing switch sequentially connects the volume and weight resistances into respective measuring bridges having automatically adjusted rebalancing resistances associated with display drums calibrated in volume and weight, connects the volume and weight resistances into a single discriminator bridge, and connects either the weight or the volume resistance into a self-balancing charge determining bridge according to the sense of the unbalance of the discriminator bridge, which is determined by the density of the package being greater or less than a predetermined value, so that light packages are charged on volume and heavy packages on weight; the automatically adjusted rebalancing resistance of the charge determining bridge being associated with a drum calibrated to indicate the transit charge, and the volume and weight resistances being switchable into a density bridge whose unbalance current operates a meter calibrated in density referred to the predetermined value. Pre-adjusted resistances are switchable in parallel with the weight or volume resistances in the discriminator bridge to vary the allowable weight for a given charge and volume, or the allowable volume for a given charge and weight; and in parallel with the weight resistance in the cost bridge to vary the weight charge rate. Fig. 1 shows a rectangular platform 66 adapted to receive a rectangular package, movable vertically in and out of a housing 21, which carries upstanding double end and side walls 67, 68, and is arranged to constitute the pan of a known vertically operating spring balance whose movement is linked by a rack and pinion to rotate a drum (Figs. 4, 5, 6, not shown) carrying a slider engaging one of five arcuate sequential contacts tapped along a resistance 251 (Fig. 8), in accordance with the weight of the package, which is placed so that a corner enters the solid angle O of the platform and the vertical walls. The inner vertical walls and the floor of the platform are slotted along three mutually perpendicular axes, and the slots carry measuring sliders 73, 74, 75 manually slidable to engage the limits of the package. Each slider comprises a pair of blocks screwed together through the associated slot (Fig. 7, not shown) and carrying an insulated wiper arm engaging a contact rail and slidably contacting one of, e.g., four insulated contacts aligned parallel to each slot on the inner side of the vertical walls and the underside of the platform 66. An insulating panel 94 adjacent to each slot carries a series of, e.g., four resistances connected between a common lead 137 and the several insulated contacts 111 (Fig. 8), the selected resistance values being such that the current in each from the D.C. supply 127, 142 is proportional to the logarithm of the positional displacement of each slider by the length, width or height of the package, and the selected resistances are parallelled so that the resultant current in RB1, RB2 and RB3 (Fig. 8) is proportional to the logarithm of the package volume. After setting the sliders to the package limits, and the ratio and zone switches 104, 105 to neutral, start switch 221 is closed to energize motor 206 from A.C. mains 164, 165, and rotate shaft 205 and the cyclically operative peripherally slotted timing discs 200 to 204. Initially disc 200 engages wiper 207 to hold motor 206 energized from the A.C. mains 164, 165 for one complete cycle until disc 200 again disengages the wiper 207 after one revolution, irrespective of the opening of switch 221. Next, disc 201 engages wiper 208, operates volume relay 115 and weight relay 198 from the A.C. mains to respectively close contacts 114, 177; 149, 169; 192, 187; and 257,295; 274, 287; 308, 302; and thus to set up a volume and a weight measuring bridge energized from the D.C. mains 142, 127. The volume bridge comprises fixed resistances 167, 175, the selected parallelled volume resistances RB1, RB2, RB3, and a rebalancing resistance 144 tapped to six insulated arcuate contacts 143 engaged by a slider 139, which is adjusted to rebalance the bridge by a motor 158 energized from the unbalance voltage by a known servo-amplifier 159. An indicating drum 101 of the variable resistance 144 is calibrated in package volume and displayed through a slot in the front panel 99 (Fig. 1). Similarly the weight bridge comprises the tapped variable weight resistance 251 responsive to the spring balance deflection, fixed resistances 285, 292, and a six-tapped rebalancing resistance 269 adjustable by a motor 278 and servo-amplifier 279 energized from the bridge unbalance voltage. An indicating drum 102 of the resistance 269 displays the package weight through the front panel. Further cyclic rotation of the disc shaft 205 disengages disc 201 from wiper 208 to release relays 115, 198 and arrest the rebalancing resistances and indicating drums at the measured volume and weight values. Simultaneously disc 202 engages wiper 209 to energize discriminator relay 109 from the A.C. mains, thus closing contacts 108, 331; 259, 338; 365, 363; 324, 333; 327, 341 ; to connect the parallelled volume resistances RB1, RB2, RB3 and the weight resistance 251 together with fixed resistances 335, 343, in a discriminator bridge energized from the D.C. mains which is normally balanced for a package of density, e.g. 11b. per 8 cu. inch. The unbalance voltage energizes servo-amplifier 337 and motor 346 to rotate switch operating arm 347 clockwise when the package density exceeds 1 lb./8 cu. inches and anticlockwise when it is below this, so that contacts 348, 362 are then closed, but remain open when the package density is equal to or exceeds the predetermined figure. Simultaneously with the operation of the discriminator relay 109, disc 203 engages wiper 210, and operates weight cost relay 263 from the A.C. mains to close contacts 262, 379; 444, 403; 424, 415; 459, 355; respectively. The weight resistance 251 and a six-tapped variable rebalancing resistance 437 are thus connected with resistances 377, 391 in a D.C. energized weight cost bridge, rebalanced by motor 409 and servo-amplifier 393 from the unbalance voltage. The indicating drum 97 of the rebalancing resistance 437 is calibrated to display the transit charge, for a package of not less than the predetermined density. Continued rotation of shaft 205 disconnects disc 203 from wiper 210 to release the weight cost relay 263, thus disabling the servomotor and disconnecting the weight resistance 251 and rebalancing resistance 437 from the weight cost bridge. After a complete revolution of shaft 205, disc 200 is disconnected from wiper 207 to disable motor 206 and arrest the apparatus with drums 101, 102, 97, indicating the volume, weight, and transit charge of the package. However, if the latter has a lower density than, e.g., 11b. per 8 cu. inches, the above-mentioned operation of the discriminator relay 109 causes the unbalance of the discriminator bridge to drive motor 346 anticlockwise to close contacts 348, 362, and operate relay 340 to close contacts 350, 360, and 350<SP>1</SP>, 360<SP>1</SP>. Volume cost relay 100 is then operated over contacts 350, 360, closes contacts 310, 310<SP>1</SP>; 120, 373; 431, 387; 421, 413; 369, 451; and breaks contacts 465, 462 to disable the weight cost relay 263 while connecting the parallelled volume resistances RB1, RB2, RB3, the rebalancing resistance 437 and fixed resistances 377, 391, in a D.C. energized volume cost bridge rebalanced by motor 409 and servo-amplifier 393 as before, so that the indicating drum 97 displays a transit charge based on the package volume. Malfunction of the apparatus on change over between weight and volume charges is prevented by closure of contacts 310 and 310<SP>1</SP> on operation of the volume cost relay 100, which replace the combined volume resistances RB1, RB2, RB3 by a lower resistance 321 in the discriminator bridge, and closure of contacts 263, 355 on operation of the weight cost relay 263 similarly replaces the weight resistance 251 by a lower resistance 450, so that if the discriminator relay 109 remains operated after operation of the volume (or weight) cost relay the discriminator bridge is imbalanced, and motor 346 remains energized in the appropriate direction to maintain the volume (or weight) cost relay operated. Closure of contacts 350<SP>1</SP>, 360<SP>1</SP> by the relay 340 holds the discriminator relay 109 operated even though disc 202 disengages from wiper 209, so that motor 346 remains operative until arm 347 disengages contact 348 to break contacts 348, 362 and release the discriminator relay 109 and volume cost relay 100; so that the latter is not left in circuit on disengagement of disc 202 from wiper 209 in a condition to be operated over closed contacts 348, 362 on the next weight and measuring operation, irrespective of whether volume or weighing is the controlling factor. The density of the package is determined by closing switch 118, so that the combined volume resistances RB1, RB2, RB3 are interconnected with the weight resistance 251 and resistances 123, 125 in a D.C. energized bridge circuit which is normally balanced at an arbitrary weight