| 摘要 |
<p>1313194 Cathode-ray tube circuits INTERNATIONAL BUSINESS MACHINES CORP 11 Dec 1970 [31 Dec 1969] 58905/70 Heading H4T A display apparatus for indicating scan speed errors in a scanning system comprises a display device 600, a test document 200 comprising a test pattern, a scanning arrangement 120, 130 141, for scanning the pattern in a plurality of scan strokes, the signals resulting from the interception of the scan strokes with the pattern being analysed so as to be capable of display on the display device, a line 614 corresponding to each intercepted scan stroke, the positioning and length of the lines indicating scan speed errors. Errors may be detected in two directions, those in the direction of the scan strokes being indicated by lines that are too short 615 or too long 616, and those in the direction of scan movement by the incorrect positioning of lines 612 at the end of the test pattern in comparison with lines 613 in the correct position in relation to starting postion 611. The lines may be intensified portions of a normally invisible reference pattern projected on a CRT 623, the pattern corresponding to that of scanner 141. Scanning speed in each direction may be independently adjusted by potentiometers 631, 633 while testing is continuously repeated. The various units of the device, e.g. height detector 300, may comprise arrangements of AND, OR gates and various types of latches.</p> |
