| 摘要 |
1481180 Character recognition systems YOKOHAMA RUBBER CO Ltd 9 Oct 1974 [9 Oct 1973] 43820/74 Heading G4R An apparatus for scanning and recognizing a mark, such as a group of alphanumeric characters, on the side of a tyre includes mechanism for positioning the tyre before a scanning system and for causing relative rotation between the scanner and the tyre so that the mark appears in the field of view of the scanner, the scanner output feeding a recognition unit. Circuitry is provided for eliminating the effects of slowlyvarying amplitude changes in the scanner output. The tyre moves along a roller conveyer and its internal diameter is determined by known means. In one arrangement, Fig. 2, when the tyre 1 reaches the scanning position it is centred on a platform 5 by arms 7. The platform is raised to the required distance below scanner 11, as determined by a photocell 9 or switch or by the previously measured width of the tyre. Scanner 11 and the light source are moved horizontally as determined by the tyre diameter to a position in which the mark will be viewed as the platform is rotated. After scanning the platform is lowered to return the tyre to the conveyer. Instead of rotating the tyre a prism and mirror arrangement may be rotated over the tyre to direct light via a dove prism to an axially-mounted scanner (Fig. 11, not shown). The mark on the tyre comprises an embossed alphanumeric group of characters which may be preceded by a start symbol. The characters are roughened relative to the background, or vice versa. The scanner output consists of a series of pulses whose amplitude represents character or background (black or white) together with a slowly varying distortion signal arising from the characteristics of the tyre surface. A circuit, Fig. 9, compares at 45 the amplitude B of the present pulse 52 with two values. If it exceeds the upper value pulse 52 is assumed to represent white, and if it is lower than the lower value it is assumed to represent black. If it lies between these values a signal #V 0 from generator 46 is added to or subtracted from B, dependent upon whether the preceding pulse S2, which had an amplitude A, represented white or black. The resulting signal B Π#V 0 is compared at 50 with A. If it is less than A pulse S2 is assumed to represent white, and if it is not it represents black. The black/white pulses pass to a recognition unit for comparison with signals representing reference characters. Read-in to the recognition unit may be prevented until the start symbol has been detected. |
