Patent GB-654075-A (GB)
Title: Improvements in and relating to a lampchanging apparatus
IPC: F21V5/04
Filed: 1947-09-25
Abstract: 654,075. Lamp changing apparatus. WALLACE & TIERNAN PRODUCTS, Inc. Sept. 25, 1947, No. 26024. Convention date, Oct. 5, 1946. [Class 75(iv)] In a lamp-changing apparatus having a plurality of electric lamps carried by a rotary lamp carrier mounted on and movable with respect to a stationary support driving means responsive to the rotary movement of the lamp carrier move the lamps in respect thereto between their operative and inoperative positions so that the longitudinal axis of a lamp at the operative position is at a substantial angle in the plane of movement of the lamp to the longitudinal axis of said lamp at an inoperative position thereof. Fig. 2 shows a lamp-changing apparatus having a main lamp 2 in the operative position within a fresnel lens (not shown) and an auxiliary lamp 4 at an inoperative position. The lamps are carried in holders 29 adjustably and resiliently mounted on brackets 26 each pivoted on pins 27, 28 (Fig. 4) between opposite ends respectively of two parallel arms 16, 17 forming a lamp carrier 5. The arms 16, 17 are spaced by a hub structure 18, 19, 20 and rotate about a sleeve member 13 fixed to a casing 6 forming part of a support structure. The pivot pins 28 engaging' in 'the ends of the arm 16 extend inwardly and are secured to arms 40 having cam rollers 39 at their free ends, which bear on a cam 35 screwed to the support structure so that on rotation of the lamp carrier to move lamp 4 into the operative position the lamps 2, 4 are moved angularly with respect to the lamp carrier to avoid contact with each other and the fresnel lens. To ensure that the cam rollers 39 are held against the cam 35 the pivot pins 27 are secured to arms 41 the free ends of which are interconnected by an adjustable spring-urged connecting link 44 (Fig. 6), having a limited expansion to correspond with the maximum relative displacement of the cam rollers 39 by the cam 35. When the lamp carrier is set to its normal position (lamp 2 in the operative position), a helical torsion spring 51 (Fig. 5) surrounding the sleeve 13 within the hub part 20 is "wound up." The arm 16 is secured to a ring gear 55 connecting via a pinion 56, shaft 57, ring gear 64, pinion 65 and shaft 66 with a wobble-bar speed control mechanism 67 69, which regulates the rotation of the lamp carrier 5 during the automatic lamp-changing operation A ratchet and pawl " free-wheel" arrangement 71, 72 (Fig. 7) on the shaft 66 allows the lamp carrier to be set by hand to the normal position without operating the speed control mechanism. The lamp carrier is held in its normal position by means of a pin 121 (Fig. 4) extending radially from the hub of the gear 64 and engaging a roller 120 carried by an armature 117 (Fig. 9) of a relay 109 which is normally de-energized. On failure of the lamp 2, a relay 101 in series with the lamp is de-energized allowing a switch 205 to close and energize the relay 109. The armature 117 is pulled down out of engagement with the pin 121 and the lamp carrier moves under the action of the spring 51 to bring lamp 4 into the operative position when an adjustable stop 76 (Fig. 2) engages the arm 16. The lamps 2 and 4 are supplied with A.C. or D.C. via the series relay 101 through a pair of switches 90, 91 operated by a cam 92 carried at one end of a shaft 105. The other end of the shaft 105 carries a lever arm 106 arranged to be engaged by a pin 107 on the ring gear 55 so that when the lamp carrier is set to its normal position the lever 106 has opened switch 91 and closed switch 90 to supply current to lamp 2. When the lamp carrier moves on failure of lamp 2 the lever 106 is moved by the pin 107 to open switch 90 and as the lamp 4 approaches the operative position the lever closes switch 91 to supply lamp 4 thus causing the relay 101 to be re-energized. A selenium rectifier unit 111 having two opposed sections 202, 203 is connected with one section 202 in series with, and the other section 203 in parallel with, the relay 109 so that A.C. or D.C. may be used to energize the relay 109 when the switch 205 is closed, and when the switch 205 is opened on the energizing of relay 101 the back E.M.F. induced in the relay 109 is dissipated through the section 203 of the rectifier unit and not across the contacts of the switch 205.. The relay 101 is of the low reactance quick acting type and has suitable tappings to allow the use of 500-750 watt or 1000-1500 watt bulbs. The relay 109 is of the high reactance slow acting type with shading coils (copper slugs discs or washers), arranged around its magnetic circuit to minimise armature vibration on A.C. The high reactance of the relay 109 ensures that no appreciable current will flow during the frequent but momentary closure of the switch 205 occasioned by the use of a flasher mechanism which periodically interrupts the current supply to the lamps. A micro-switch 124 connected via terminals 127, 128 to a suitable warning mechanism (electric light or bell), is arranged to be operated by a cam 122 on the shaft 105 when the lamp carrier moves on failure of the lamp 2. When reset by hand the lamp carrier is moved until a stop 74 (Fig. 2) engages the arm 16 where the lamp 2 is then just beyond its operative position. When released the spring 51 returns the carrier until the pin 121 once again engages the roller 120 on the armature 117 of the now de-energized relay 109, the lamp 2 being then in its operative position. Fig. 10 shows an arrangement wherein the angular movement of two lamps 129, 132 with respect to a lamp carrier 136 is effected by a train of gears 150, 151, 152 arranged so that the lamp 129 in the operative position is vertical whilst the lamp 132 in the inoperative position is at an angle to the vertical, thus allowing large-size lamps to be used. U.S.A. Specification 2,289,315 is referred to.