| 摘要 |
<p>1,089,120. Digital shaft encoders. LITTON INDUSTRIES Inc. Nov. 30, 1965 [Jan. 4, 1964 (2)], No. 15241/67. Divided out of 1,089,119. Heading G4H. A digital shaft encoder has a commutator having a plurality of discrete conducting and non-conducting segments within each of a number of annular zones, one for each digit, there being a number of redundant contact locations defined by the position of a set of interconnected contacts for each zone, certain of the zones being divided into a number of sub-zones and both the corresponding segments of the sub-zones and the contact locations being displaced in the direction of movement of the commutator. The commutator is read by the V-scan method, a single reading being obtained from the least significant zone 0, Fig. 3, and lead and lag readings from all the other zones, one of which is selected according to the reading of the next lower digit. Three contacts are provided for each reading in case one or more contacts becomes defective. In the lowest zone 0 three are in corresponding positions spaced four pitches apart. In zone 1 they are spaced by two pitches and in zones 2 and 3 they are in adjacent pitches. This would be inconvenient in zones 4, 5 and 6 and these zones are accordingly divided into annular sub-zones, e.g. 4a, 4b and 4c, displaced relatively to each other so that the contacts can be placed in the same position in the corresponding pitch but at a convenient distance apart. The contacts of each group are interconnected and connected to output terminals.</p> |
