| 摘要 |
810,409. Indicating the position of marked articles. STANDARD TELEPHONES & CABLES Ltd. May 17, 1957 [May 24, 1956], No. 15791/57. Class 40 (3). In apparatus for detecting whether a letter or other object is in a normal or inverted position, n photo-electric cells, each sensitive to a different colour, obtain signals from two different positions on the letter in either one of which positions a postage stamp or other mark may occur and from a third position at which the postage stamp will not occur, and two n-phase and neutral circuits are provided, each corresponding to a separate one of the first two positions, the phases of which are energized in proportion to the signals due to the separate colours derived by the photo-cells from the first two positions on the letter divided by the signals due to the corresponding colours derived by the photo-cells from the third position, the currents in the two neutral conductors being compared to provide an indication of the position of a stamp on the letter. Three areas F1, F2, F3 of a letter 1, Fig. 2, are successively illuminated by a light source and reflected light from these areas falls upon photo-electric receivers Er, Eg, Eb, Fig. 4, sensitive respectively to red, green and blue light. The voltages due to each colour from each area are applied to respective storage condensers Cr1-Cb3 via a switch 3. Each phase of a three-phase voltage source 4 is connected to respective dividing devices Dr, Dg, Db which are connected respectively to the condensers Cr2, Cg2, Cb2 so that each dividing device has an output proportional to the reciprocal of a respective one of the colour signal voltages derived from the area F2. The output of the dividing device Dr is applied to multiplying devices Mr1, Mr3 where it is multiplied by the red signal voltages stored on condensers Cr1, Cr3 derived from the areas F1, F3. Similarly the outputs of the dividing devices Dg, Db are applied to multiplying devices Mg1, Mg3, Mb1 Mb3 and there multiplied by corresponding colour signal voltages derived from the areas F1, F3. The outputs of the multiplying devices Mr1, Mg1, Mb1 are connected to equal resistances 5 of a three-phase and neutral system 6 and the outputs of the multiplying devices Mr3, Mg3, Mb3 are connected to equal 5 resistances of a three-phase and neutral system 7, in which the vectoral additions of the voltage outputs of each group of multiplying devices are represented by the neutral currents of the three-phase systems 6 and 7. By comparing the two neutral currents of the systems 6 and 7 by means of a polarized relay 10, an indication is given as to whether a stamp is in the area F1 or F3. |
