Patent GB-1095452-A (GB)
IPC: H04N1/393
Abstract: 1,095,452. Copying for scanning. R. HELL. Dec. 28, 1964 [Dec. 27, 1963], No. 52585/64. Heading H4F. In an arrangement for reproducing a picture original with a variable reproduction scale that is adjustable to any desired value, in which the picture original and the recording surface are positioned on drums rotating at the same rotational speed and the scanning and recording members are continuously advanced at right angles to the scanning direction or make an advance step at right angles to the scanning direction after each line scanned, the picture signals from the scanning member are stored and the play back and reading-in speeds are adjusted to correspond to the selected reproduction scale and to the screen number selected for the reproduction, the advance speed or the amount of advance of the scanning and recording members being similarly adjusted to correspond to the selected reproduction scale and to the line density (screen number) selected for reproduction. The picture signals may be stored digitally using ring-core matrices or magnetic tape after having been previously quantized and coded or they may be stored in analogue fashion using magnetic tape. In a first embodiment, Fig. 1, an original 2 to be reproduced is positioned on a rotating drum 1 and scanned by a photo-electric scanning device 3, the scanned brightness values being changed into voltages and fed to an analoguedigital converter 5 whose outputs are connected to a coding device 7. The analogue converter quantizes the instantaneous amplitudes of the picture signal into a finite number of discrete amplitude steps, e.g. 32 steps, which are converted in the coding device into the binary code using 5-digit pulse combinations. The five output conductors 8 of the coding device 7 which carry binary voltage combinations are each connected in parallel to five gates 9, 9<SP>1</SP>. . . 9<SP>11</SP> up to 13, 13<SP>1</SP> . . . 13<SP>11</SP> arranged in the input conductors of ring core storage groups 19, 19<SP>1</SP> . . . 19<SP>11</SP> in which a scanned picture line is stored, the individual groups being operated successively. At the start of each line a cam 22 on the drum shaft switches on pulse generator 25 which supplies pulses at frequency 1 Mc/s. to a ring-counter 28, the number of steps of which is adjusted to control the timing frequency at which the coded picture signals are stored in the ferrite cores in the storage groups. This timing frequency is calculated from the required ratio of enlargement or reduction of the original and the size of the picture points, i.e. the screen number. The timing pulses from the ring counter 28 activates the column conductors 33 . . . 45 up to 33<SP>11</SP> . . . 4511 successively by means of storage counters 32 . . . 32<SP>11</SP> and thus the 5-digit pulse combinations are stored. Similarly, the pulses from playback ring counter 68 control the interrogating counters 71 . . . 71<SP>11</SP> and the output 5-digit pulse combinations at the playback frequency are fed via gates 60 . . . 64 up to 60<SP>11</SP> . . . 64<SP>11</SP> and conductors 78 to decoding device 79, digital-analogue converter 81 and recording device 84. At the end of each line a cam 54 on the shaft of drum 1 closes contact 53 and a pulse is transmitted to switch 56 which reverses causing AND-gate 27 to close and preventing pulses from reaching ring-counter 28. The pulse occurring in conductor 89<SP>11</SP> when the last column of the last storage group has been reached reverses switch 24 via an OR-gate 90 and stops generator 25. The ratio of the read-in to playback speed of the ring-cores, i.e. the desired ratio of the original to the reproduction, is the same as the ratio of the read-in ring counter 28 timing frequency to the playback ring counter 68 timing frequency, both of which are obtained by division from generator 25. The timing frequency for playback is lower for enlargement and higher for reduction than the timing frequency for storage. For enlargement although it is possible to begin the playback immediately after the first picture point of the first picture line has been stored, in the embodiment a small delay is introduced, e.g. time to fill the first storage group 19. For reduction the start of the playback of data in the store is delayed, for a calculated preset number of timing pulses by means of advance counter 94, until after so many picture points have been read-in that the playback ends at least the time taken for reading-in one picture point later than the reading-in of the last picture point of a line. Recording member 84 may be an engraving tool or if the equipment relates to a colour correcting scanner then member 84 is a recording lamp, several simultaneously-operable ring core storage matrices being used, i.e. one for each colour separation negative or colour separation printing block. Two line storage devices may be used for storing alternate lines. In a second embodiment, Fig. 2 (not shown), the 5-digit picture points pulse combinations are recorded on a magnetic tape (111) by means of recording heads (106-110) and played back by means of heads (157-161). The five tracks correspond to the five rows of ring cores in the first embodiment and the enlargement or reduction of the reproduction compared to the original is effected by causing the magnetic tape to travel faster or slower past the recording heads than past the playback heads. The tape is started simultaneously at the recording and playback ends at the start of scanning of each line of the original by means of cam (125) on the shaft of drum (1) which closes switch (124), thus activating clutches (122) and (123) causing synchronous motors (118) and (119) to drive tape drive rollers (137) and (138). While a picture line is recorded the stored preceding picture line is played back and the changes in length of the portion of magnetic tape between the recording and the playback heads which occur during each transmission of a picture line are compensated by a balancing loop (183). At the end of each line on the original, cam (150) releases the clutch (122) stopping the tape, and at the end of each line on the reproduction, cam (173) releases clutch (123) stopping the tape at the playback heads. Magnetic dashes (185) are recorded on the tape as a sixth track by means of timing head (148) and are detected by playback head (162) and used to activate the clutch (123). The tape may be an endless loop (181) being an erasing device, or it may be long enough to allow a whole picture to be stored. Two endless tapes may be used to store alternate lines.