Patent GB-1182873-A (GB)
Title: Editorial Correcting Typewriter Utilising Data Search and Information Retrieval Techniques.
IPC: B41J5/38
Filed: 1968-04-17
Abstract: 1,182,873. Electric typewriter control. INTERNATIONAL STANDARD ELECTRIC CORP. 17 April, 1968 [26 April, 1967], No. 18081/68. Heading G4H. An editorial correction typewriter comprises means for storing the address of a point in a text where a correction is described, means for automatically typing out a clean copy of the text, means for continuously comparing the stored address with the text and means responsive to the detection of the address in the text for stopping the typewriter. If the invention is applied to the typing of a letter, a tape is first prepared as the typist types the letter; the tape causing the same letter to be typed when it is run through the typewriter. To make editorial corrections to the letter, the typist determines where the corrections are required and makes a correction memory tape by typing ten or more of the characters which immediately precede the point where the correction is required, followed by a blank code character of all " 1's ". When the tape is now run through the typewriter, the typewriter types out a copy of the letter up to the point where the characters of the tape agree with the characters on the correction memory tape, and there stops. If this proves to be not the required point, the typist pushes a start button and the typewriter resumes its automatic typing of the letter until it again finds 4 characters agreeing with those on the correction tape. A number of corrections may be made, the correction tape defining the successive points on the letter in the same way. The correction tape is run through a reader 50 under brushes 13. A perforation causes a ground signal to be applied to the brush. Each brush is connected via a resistor 56 to a summing bus 57. The bus 57 is connected via three resistors equal to those 56, and one 60 having half that value, to a battery 58. If the word ready by the brushes 13 contains 3 or less " 1's " the bus has earth potential. The blank code character is detected by AND gate 78 responding to seven " 1's " to stop the tape bus circuit 81 and to cause flip-flop 82 to be set thereby enabling typewriter Run/Stop circuit 83. The original tape then starts passing through the reader 52, signals on lines 84 causing the message to be typed out. Each character is reduced to a binary signal according as to whether it contains 3 or less " 1's " or 4 or more and these bits are passed via gate 86 through shift register 85. The gate 86 is inhibited between characters by sprocket hole contacts 69, and when a character of all " 1's " is read by gate 89. When the comparator 92 indicates that the contents of shift registers 76 and 85 agree a signal is applied to circuit 83 to stop the typewriter. The typist makes sure that the typewriter has stopped at the proper place and types the new passage in the normal way. Otherwise key 94 is pressed and the typewriter continues until another agreement is reached. After the correction has been made the typist momentarily presses the correction tape reader start key 72 and circuit 81 restarts the tape, the blank character moves away and signal 79 vanishes, flip-flop 82 being reset via capacitance 96. The reader 50 reads out the ten characters marking the position for the next correction and the detection of a blank character by gate 78 starts the typewriter on the next portion of the message. Instead of using a correction tape the address of a desired correction can be entered directly into shift register by a typewriter. Instead of using a shift register, the typewriter can be stopped upon the detection of any selected signal by connecting the seven bit leads via jacks to an AND gate. Thus, for example, the jacks may be set to respond to the dollar symbol so that the prices quoted in a typed letter can be altered.