Abstract: In an improved method of etching apertures in a thin metal sheet to form a shadow mask for a color picture tube, the metal sheet has a first acid-resistant stencil on one major surface thereof and a second acid-resistant stencil on the other major surface thereof. At least one of the stencils has openings therein at locations of intended apertures. The improvement comprises the steps of magnetically holding the metal sheet with a flat magnetic assembly, and moving the magnetic assembly magnetically holding the metal sheet thereon through an etching chamber. The magnetic assembly includes a magnetic layer that is supported on an acid-resistant board.

Abstract: In an improved method of etching apertures in a thin metal sheet to form a shadow mask for a color picture tube, the metal sheet has a first acid-resistant stencil on one major surface thereof and a second acid-resistant stencil on the other major surface thereof. At least one of the stencils has openings therein at locations of intended apertures. The improvement comprises the steps of magnetically holding the metal sheet with a flat magnetic assembly, and moving the magnetic assembly magnetically holding the metal sheet thereon through an etching chamber. The magnetic assembly includes a magnetic layer that is supported on an acid-resistant board.

Abstract: In accordance with the present invention, a display apparatus 8 comprises a color CRT 10 having an evacuated envelope 11 with a faceplate panel 12 sealed to one end of a funnel 15 that is closed at the other end by a neck 14. The faceplate panel has a luminescent screen 22 on an interior surface thereof. A shadow mask 25 is located in proximity to the screen. The shadow mask comprises a metal sheet having a central portion and an exterior portion with a plurality of apertures 40, 43 therethrough. An electron gun 26 is disposed within the neck for generating and directing electron beams 28 toward the screen. A deflection yoke 30 is disposed around the envelope at the junction of the neck and the funnel. The yoke deflects the beams to scan a raster across the screen.

Abstract: A piston or rod seal comprising a scraper ring 2 which is made of a PTFE material and supported in a first groove 1 open toward the relatively moving machine part. This ring is pressed against the relatively moving machine part 5 by an O-ring 4 made of an elastomeric material and supported on the bottom 3 of the first groove 1. On the side facing the relatively moving machine part, the scraper ring 2 is bounded by at least two sealing edges 7 separated by a second groove 6 and, on the side facing the O-ring, it is bounded by a conical surface 8. The second groove 6 has a rounded bottom having a radius R which approximately corresponds to the radial depth T of the second groove 6. The conical surface overlaps the radial planes of all sealing edges 7 while avoiding any considerable changes in directions.

Abstract: In a telescoping shock damper, a seal which seals the plunger rod against the barrel comprises an inside lip ring of PTFE and an outside supporting ring of rubber. The lip ring and supporting ring are integrally joined together and are defined by faces running preferably radially which merge with one another.

Abstract: A system for controlling a flexible roof assembly of the type used to cover large structures determines the actual variable height of one or more sections of the roof assembly with respect to a fixed reference point and regulates the apparatus for elevating the roof assembly to accurately control the position of the roof assembly. The system includes a signal generator for generating a signal corresponding to the actual height to indicate a change in height of the roof assembly. The system may also include an apparatus for detecting the presence of either ice or snow in an area of an outer surface of the roof assembly. The detecting apparatus includes a collecting device that is oriented to collect snow and ice that is accumulating and a sensor unit directed toward the collecting device to detect an accumulation of ice or snow that reaches a specified depth.