Patent GB-1317542-A (GB)
Title: System for providing a copy of electronically received information
IPC: G09G1/26
Filed: 1971-04-26
Abstract: 1317542 Cathode-ray tube circuits TEKTRONIX Inc 26 April 1971 [4 May 1970] 11301/71 Heading H4T Data stored on the target of a direct viewing storage tube 10 (Fig. 1), is read-out and recorded on a record medium 100. The data derived from a source 80 (e.g. a computer) is laid down on the target when the linked switches of a switch unit 118 are in the position shown and when an operator viewing the screen of tube 10 desires to make a permanent (hard) record of the data displayed, operation of a push-button (not shown) supplies an input on line 150 to a start flip-flop 132 in read-out circuit 116 which puts the linked switches on their right-hand contacts and supplies X and Y scanning waveforms to the deflection plates and a train of interrogation pulses 78 to the beam intensity control electrode 16 of tube 10, the duration of the pulses 78 being made sufficiently short to prevent destruction of the stored data. The latter is thus read-out, non-destructively, in the form of pulses 53 which are supplied via transformer 70 to an amplifier and flip-flop 72 producing amplified and stretched output pulses for control of the beam intensity in a display tube 84. The horizontal beam deflection of the latter produced by the X-ramp generator 126 (which controls the X deflection of tube 10 in the recording mode) and a slow vertical deflection of the beam is produced by the attentuated output of the Y-ramp generator 130 (which also controls tube 10 in the recording mode) to avoid damage to the screen which consists of a narrow elongated phosphor strip 98 along the length of which successive horizontal scans are produced. The fluorescent image produced on the phosphor strip 98 is directed via a fibre optic member 96 on to a web of sensitive material (dry silver paper) 100 which is caused to move by being "pinched" between a continuously moving roller 106 and a clutch operated roller 104 controlled by solenoid driver 158, the (vertical) movement producing the required vertical scan, the web 100 then passing a heating means 114 which "develops" the sensitive material individual sheets of which are produced by a cutter 108. In the operation of the read-out circuit 116 a compare circuit 134 compares the Y-ramp waveform with three voltage levels T 1 , T 2  and T 3 . Level T 1  is reached shortly after initiation of the Y-ramp (to allow time for movement of the web 100 to commence) and an output is provided to the switch driver 148 to position the linked switches on the right-hand contacts. Level T 2  is reached near the end of the Y-ramp and an output is produced which returns the linked switches to the position shown and finally when level T 3  is reached, an output is produced which changes the state of flip-flop 132. The latter then supplies an output which, via gate 154 and one-shot multivibrator 156 operates solenoid driver 158 to declutch roller 104 and to operate the cutter 108. The length of the X-deflection is controlled by a compare circuit 128 which during retrace intervals inhibits the production of the interrogation pulses 78 and causes generator 76 to supply reset pulses on lead 162 for the "stretching" flip-flop in amplifier 72 and via gate circuit 136 supplies a blanking pulse to the latter amplifier.