Patent GB-819470-A (GB)
Title: A new or improved means for performing audible reproduction or other actions in response to printed or like record data
IPC: G06V10/10
Filed: 1954-11-06
Abstract: 819,470. Photo-electric reading devices. BIRMINGHAM, LORD MAYOR, ALDERMEN, & CITIZENS OF, and DAVIS, J. H. Nov. 7, 1955 [Nov. 6, 1954; Dec. 11, 1954], Nos. 32181/54 and 35920/54. Class 40 (3). Recorded items of intelligence in the form of letters, words, symbols, &c., impressed on a suitable base are examined item by item by means of a cathode-ray tube flying-spot scanner CR1 to produce a complex (video-type) signal in a photo-electric cell V4, the signal being applied via an amplifier 18 to an integrator 19 to produce a simplified signal in the form of a voltage the amplitude of which directly indicates the item of intelligence. The output voltage is then employed to initiate same action, such as the reproduction of the sound corresponding to the word, letter, &c., in the same or a different language, or the printing of the intelligence normally or in braille. The essential feature of the invention resides in the production of the simplified signal by means of the integrator. This comprises a capacitor charging through a valve receiving the photo-electric cell signal on its grid. The circuit in effect performs an integration with respect to time of the portions of the cell signal corresponding to the passage of the scanning spot over either the white or black portions of each letter, word, &c. As illustrated the integrator output voltage is utilized to control the production of corresponding.sounds, this being effected by means of a vocabulary unit including a cathode-ray tube CR2 bearing on or adjacent its face a series of variabledensity sound tracks, each corresponding to the sound of an item of intelligence. The tracks extend horizontally and are disposed in a vertical column so that the application of the integrator output voltage over leads F and G to the Y plates positions the beam adjacent the correct sound track. The application of a deflection voltage from a circuit 13 to the X plates then traverses the spot over the sound track resulting in the production of an audible output via photo-electric cell 16 and sound reproduction unit 16. When the apparatus is arranged for printing in braille, Fig. 8 (not shown), the X plate deflection is dispensed with and the vertical position assumed by the cathode-ray spot under the control of the integrator output voltage is detected by a vertical array of photoelectric cells, which, through suitable circuits, control the selection and actuation of an appropriate combination of braille punches. For this application, the apparatus is necessarily set up to examine the original intelligence letter by letter. In operation of the apparatus generally, cathode-ray tube CR1 is scanned along a line of intelligence under the control of line scan circuit 10 connected to the X plates and is subjected to a higher speed transverse deflection of sine wave or triangular form applied from oscillator 11 to the Y plates. At the completion of the scanning of one item of intelligence, either a letter or word depending on the application, a characteristic output from amplifier 18, indicating the incidence of the scanning spot on an all-white area, stops the X-direction scan by a connection over lead D. Simultaneously a connection over lead H releases the normally cut-off beam of cathode-ray tube CR2 and, where the tube functions to produce a sound output, initiates the X-direction scan. In response to the integrator output voltage over leads F and G the tube spot will by this time be positioned appropriately vertically. At the completion of the sound reproduction or printing operation, a signal over lead H from the sound reproduction circuit or the printer operates through release circuit 14: (1) to release the X-direction scan in tube CR1 over lead K and allow examination of the next item of intelligence, (2) to discharge the integrator capacitor over lead Q to prepare the circuit to respond to the next intelligence signal, and (3) to extinguish over lead P the beam of tube CR2 and if necessary to reset the X-direction scan circuit. Where the apparatus is used with a wide range of intelligence items, it may be necessary to utilize more than one column on the face of cathode-ray tube CR2. The integrating circuit capacitor is automatically discharged each time it acquires a potential corresponding to the full height of a column and each discharge operates via a stepping circuit, Fig. 9 (not shown), in the X-direction deflection circuit of tube CR2 to displace the spot on to the next adjacent column. As an alternative to flying- spot scanner CR1 and photo-electric cell V4, reference is made to the use of a photo-electric mosaic scanned by an electron beam. Detailed circuits for carrying out the invention are described with reference to Figs. 2-7 (not shown).