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).
Explaining the working principles of the Trippe Lamp, focusing on its parabolic reflector design.
| Identifier | ExFiles\Box 167\1\ img007 | |
| Date | 2nd September 1935 guessed | |
| THE TRIPPE SAFETY SPEED LIGHT CO. LTD. LIVERPOOL. 3. THE TRIPPE LAMP. The patented and other features which render the TRIPPE Lamp one of the most efficient in use at present, are intimately concerned one with another, and the failure of any section of the chain will have an immediate effect on the efficiency of the Lamp. In order to make it clear that insistance is necessary that TRIPPE bulbs and other genuine TRIPPE parts only be used as spares, consideration is invited to the principles on which the Lamp works. Sketch 1. "B" is a parabolic reflector, and "A" is the focus. If "A" consists of a minute light centre, and "B" is made with extreme accuracy, the image of "A" will be reflected forward an infinite number of times; in effect, the number of images will be equal to the number of times the area of "A" exposed to the reflector will divide into the inside area of "B". Provided that "B" is accurate, and "A" is sufficiently small, this magnification is infinite, and has much to do with the power available in the TRIPPE Lamp. In the Lamp, "A" is represented by the filament in the bulb, and this is made as small physically as possible for the wattage. As there is only one place in focus, the tolerance to which the filament is made on both axis in the bulb is much less than average manufactured automobile bulbs, and must be exceedingly accurate. As also the parabola "B" governs the magnification, it can naturally be assumed that if this is made large, more light will be projected. This is correct, provided the accuracy of the parabola is preserved. If this is lost, the image projections are distorted and light interference causes more losses than gained by increased size. Hence, 7" to 7 1/2" is the limit set by production whereby accuracy can be maintained. To increase this size would mean an enormous increase in production cost, as metal would not be a suitable material for construction. Hence, the TRIPPE Lamp has its back reflector 7 1/2 diameter, and at this is extremely accurate. Research has indicated that the kind of silver used in plating, and the actual finish of the surface, can account for up to 30% variation of light, though not discernable by eye examination of the reflector. | ||