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).
From The Trippe Safety Speed Light Co. Ltd. describing the function and design of anti-dazzle lamp reflectors.
| Identifier | ExFiles\Box 167\1\ img008 | |
| Date | 2nd September 1935 guessed | |
| THE TRIPPE SAFETY SPEED LIGHT CO. LTD. LIVERPOOL. 3 - 2. The TRIPPE reflectors have only some 11% loss, on finish. The foregoing covers the accuracy of the various aspects of the light source and reflection, as applied to any Lamp, and particularly, the TRIPPE. Once these have been provided for, the particular method of applying the light to the road is the matter of design. In the TRIPPE Lamp anti-dazzle has been achieved with no loss of light power. To cater for this the Lamp is made with two reflectors. By arranging that light "A" is slightly ahead of actual focus of "B" (which is at "X" - sketch 2.), the rays from the reflector converge, the amount of convergence being controlled by the amount "A" is ahead of point "X". In the TRIPPE lamp the rays converge about 30' from the Lamp. Sketch 2. By placing a half reflector in the lower half of the Lamp, so positioned as to be in accurate focus to "A", all the light falling on this section is projected forward at an angle to the axis of "B" determined by pivots at the base of the reflector. Sketch 3. Thus, in the Lamp, by virtue of the accuracy, and the positioning of the two reflectors, all light falling on the top half is reflected downward, and all falling on the lower reflector is concentrated forward and slightly downward, if so adjusted. No reflected rays rise above horizontal when the Lamp is vertically mounted. The projected light pattern and the path of the respective rays is as under. - In the above way the light reflected is controlled as desired, and directed in the most serviceable direction, no attempt being made to dim or blank the reflected rays. The only rays not yet dealt with are those which emanate from the actual filament, and leave the Lamp without falling on the reflector at all. These are only harmful when above the horizontal. To trap these, use is made of a patented Cowl, mounted to cut off light from the area on the bulb shaded in. No light falling on the reflector is | ||