GB599977A - Improvements in indicating scales - Google Patents

Abstract

599,977. Indicating - apparatus. BRITISH BROADCASTING CORPORATION, and BUDD, S. W. Sept. 26, 1945, No. 25010. [Class 106 (iv)] [Also in Group XL] An indicator scale for a variable condenser or other component comprises a sector-shaped scale member and an opaque index member arranged so as to cover the scale member completely in one position and to uncover the scale progressively as relative movement takes place about the centre of the circular arcs. The index member has at least as great an angular extent as the scale, and the faces of the members have sharply contrasting surfaces. An indicator scale 10 consists of a semicircular segment of a disc bearing graduations, the other segment 11 being treated to have strongly contrasting light reflecting properties. The semicircular index member 12 is opaque, and its surface has the same light reflecting properties as the segment 11. The index member 12 is rotatably mounted on a spindle 13, passing through the centres of the segments. The scale is covered completely for one position of the index, and is uncovered as the index moves. The index member may have a greater angular extent than the scale, or both members may extend over more than 180 degrees, when the scale member cannot be wholly exposed.. The index may be formed as an opaque segment of a transparent disc, while the segments 10, 11 may be made separately. Preferably, the scale member is arranged behind a window of the same contour in a casing, the front face of which has similar light reflecting properties to the index member.