Patent FR-1417404-A (FR)
IPC: G06K9/68
Filed: 1964-10-29
Granted: 1965-11-12
Abstract: 1,016,569. Recognizing characters and spoken words. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 22, 1964 [Nov. 1, 1963 (2)], No. 43041/64. Heading G4R. In a system for recognizing specimens, each specimen belonging to one of a number of classes, signals are derived representing a specimen and applied to a plurality of test circuits for each class, each test circuit being adapted to detect the presence of certain signals or combinations of signals characteristic of the class and to generate an output the output of one test circuit enabling the next test circuit and so on. The test circuits for each class control an indicator indicating whether the specimen belongs to that class. In the form of Fig. 1 the specimens, which are represented by ten-bit binary words, may be different versions of alphabetic characters A, B, C &c. or words spoken by different speakers. Examples are given of nine specimens belonging to the "A" set, nine to the " B " set and nine to the " C " set. In each set there is a corresponding channel consisting of a string of test circuits. The signals from the input means 10 are applied to all the circuits in each channel. In channel 1 test circuit 12 makes a first test, e.g. it looks for a " 1 " bit in the third position. If the specimen signals pass this test a signal on lead 18 enables test circuit 30. A signal on lead 18 is produced by any specimen belonging to set A and by some specimens belonging to sets B and C. If the specimen does not pass, it does not belong to set A; the reject lead 24 activates indicator 92. Test circuit 30 is designed to detect members of sets B and C to produce a signal on lead 36. Some specimens from set A will also pass circuit 30 and give an output on lead 36 but any specimen which has passed circuit 12 and is rejected by circuit 30 must be a member of set A. The reject lead 42 is therefore connected to the A indicator 100. Circuit 48 tests for some other characteristic of the A set and is enabled by a pass signal on lead 36. It is similar to circuit 12 in that it is designed to be passed by all the specimens of set A but is narrower in that it is designed to be passed by A specimens which have passed test circuits 12 and 30. The pass lead 54, when energized, enables the last circuit 66 and the reject lead 60 activates indicator 92. Circuit 48 is passed by all set A specimens which have passed circuit 30 and by a few from sets B and C. These are filtered out in the last circuit 66 which applies a test for specimens not in set A. A reject signal on lead 70 indicates that the specimen must be one of set A and indicator 100 is activated. If the specimen passes this circuit it does not belong to set A and lead 68 activates indicator 92. The other two channels are similar, except that they do not have the fourth circuit. The test circuits consists of inverters and gates to detect the appropriate combinations of " 1 " and " 0 " bits. In a second embodiment, Fig. 7, the indication that a specimen belongs to other sets is obtained by taking the pass signals from the other channels. Circuits 12, 14, 16 are, as before, designed to be passed by all specimens from sets A, B and C respectively. If a specimen passes circuit 12 and is rejected by circuits 14 and 16 it must be one of set A and cannot be in sets B or C. The pass outputs from circuits 14 and 16 are applied via OR gate 87 to inverter 125 so that if neither is present AND gate 127, receiving the output of the inverter and the pass signal on lead 18, indicates that the specimen is in set A. Indicator 119 is activated accordingly. However, if either of the B or C circuits 14 or 16 gives a pass output this is gated at 81 with the signal on lead 18 to enable the output gate 155 of the next test circuit 30. Circuit 30 in this embodiment is designed to detect specimens from set A (rather than from the other sets as in the first embodiment). The second level consisting of circuits 30, 32 and 34 operates in the same way as the first stage.