From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Diffusion scheme for instrument board lighting.
| Identifier | ExFiles\Box 62\2\ scan0060 | |
| Date | 15th April 1932 | |
| X6141 H.{Arthur M. Hanbury - Head Complaints} from E.{Mr Elliott - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} c. For. c. Hs.{Lord Ernest Hives - Chair} --s---------- E.2/HP.15.4.32. Instrument Board Lighting. ------------------------ The best scheme we know of for illuminating the instrument dials is what we call the diffusion scheme. With this arrangement each instrument is provided with a glass of its own thick enough to have a 45º bevel around its circular edge with a face width of about .125". The instrument box cover is made to just come up and touch the face of the glass, but leaving an annular space between the body of the instrument and itself which is filled by the bevel. There are two bulbs arranged within the instrument patch box but no direct light is able to fall upon the instrument dials. The back of the instrument plate is painted white, and diffused light passes through the bevelled edges of the instrument glasses, and provides a soft and uniform illumination of the dials. This scheme is most successful in practice in avoiding glare, but it is not generally used as it is a little more expensive. From our point of view it has the advantage of providing each instrument with its own glass which would wash out a lot of the trouble we have had with suppliers, and it also cuts out the use of a large sheet of glass which is apt to be troublesome owing to reflections. We propose this scheme for Japan III. E.{Mr Elliott - Chief Engineer} | ||