Patent GB-277344-A (GB)
Title: Improvements in devices for transmuting the energy of visible light rays
IPC: G05D23/275
Filed: 1927-09-07
Abstract: 277,344. McCabe, I. E. Sept. 7, 1926, [Convention date]. Electrically controlling fuel and air supplies.- A device for transmuting the energy of visible light rays comprises two interconnected sealed gas containers, the walls of one of which are transparent and those of the other coloured so that, when the device is subjected to visible light, the absorbed rays increase the temperature of the walls of that container, expand the gas therein, and impart a movement in the direction of the other container to a movable seal situated between the containers. Such a device is shown in Fig. 1 (Cancelled), applied to an electric switch. Two bulbs 2 are connected by a restricted portion 1 containing sufficient mercury 3 to form a seal between the bulbs. One electrode 4 extends into the mercury and both electrodes are connected to binding posts 8. The right-hand bulb is covered with lamp-black or other absorbent material which, when the device is subjected to visible light, absorbs the radiant energy and converts it into heat, thus expanding the gas within and driving the mercury so that it contacts with the left-hand electrode 4 to close the circuit. Instead of a lamp-black covering the right-hand bulb could be of coloured glass, for instance, green bottle glass, whereas the other is of any kind of clear glass which absorbs about the same amount of infra-red rays as the bottle green glass. The advantage of this form is that, whereas the lampblack covering absorbs radiant energy in the absence of visible light more quickly than the clear bulb and consequently the switch would be operated by an increase of the surrounding temperature, in the green bulb form the bulbs absorb radiant energy in the absence of visible light equally and so heat alone will not operate the switch. When it is not convenient to provide glasses which absorb infra-red rays equally, a screen of glass may be interposed between the bulbs and the source of light, the glass known under the registered Trade Mark "Pyrex" being suitable for absorbing such rays. Such a screen is shown at 11 in Fig. 3 between the bulbs in the container 6 and the flame of a domestic liquid fuel burner. The burner comprises a draught pipe 13, electric fan motor 14, oil nozzles 16, and ignition device 17. The operation is controlled bv a room thermostat T, boiler control B, and safety control C, which latter, when the thermostat T closes the circuit, closes the circuit to the, motor 14 and ignition device 17, and, when the circuit has been closed by the switch in casing 6, cuts out the ignition device. If the burner flame fails, the switch in casing 6 opens the circuit to operate the safety switch and open the motor circuit. The control C comprises a pivoted mercury tube biassed co open position and a thermally-operated member to engage and hold it closed, so that when the full current passes through the thermal member the circuit is broken. A shunt circuit across the binding posts 8 which is made by the switch 6 takes sufficient current to allow the thermal member to hold the switch C closed. Lenses may be employed when the light source is remote from the switch, or where the switch is small. By proper selection of the glasses the device may be operated at various points of the visible spectrum. The Specification as open to inspection under Sect. 91 (3) (a) states also that the device may be operated by rays of the invisible spectrum, such as infra-red rays. This subject-matter does not appear in the Specification as accepted.