GB1482641A - Scanning arrangements - Google Patents

Abstract

1482641 Television EMI Ltd 12 Nov 1974 [22 Nov 1973] 54283/73 Heading H4F Picture disturbance resulting from a faulty detector or unbalanced detector output in an array of ten detectors 5, Fig. 1, in an infra-red scanner, is distributed over the display by arranging for the picture information of corresponding lines of the display in consecutive frames, to be derived from different detectors in the array 5. Radiation enters the scanner via window 1 and is reflected by a rotating mirror drum 3 and an oscillating mirror 4 on to the array 5. The drum 3 provides the horizontal scan and mirror 4 the vertical scan. The ten detector outputs, each representing one strip of picture, are amplified, A-D converted, and applied by a commutating device, in block 6 to a ten line store 8 or 9. Simultaneously the previous ten lines of information which will have been applied to ten line store 9 or 8 respectively are read out, D-A converted, and applied to a display device 11. A timing circuit 7 controls the operation of each stage, more especially it controls the movement of the drum 3 and mirror 4 so that drum 3 effects 62À9 sweeps per frame, yielding 629 lines of information of which four are rejected, and mirror 4 oscillates at the field rate. Fig. 3 indicates the manner in which the origin of the picture signal for each line changes between consecutive frames under this arrangement. Stores 8 and 9 may comprise digital shift registers or charge transport devices, in the latter case the D-A converters may be omitted. A signal multiplexing arrangement may be utilized prior to the A-D converter in block 6. Ten detectors may be employed for each line yielding a 10 Î 10 matrix thereof.