Patent GB-874879-A (GB)
Title: Improved traffic signal
IPC: G08G1/096
Filed: 1959-02-16
Abstract: 874,879. Road signals for controlling traffic. LIGHT, L. F. Feb. 12, 1960 [Feb. 16, 1959], No. 5282/59. Class 118. In a traffic signal comprising at least one red and one green light, the amount of time which will expire before either light changes is shown by the consecutive illumination, or extinction, of a plurality of parts of at least one stationary area between the lights. The area 15 (Fig. 2) between the red light 17 and green light 19, comprises a translucent screen behind which a number of bulbs 21 are mounted. These bulbs are consecutively switched on or off thus giving a visual indication of how much time will elapse before the lights change, this change occurring when complete extinction or illumination of area 15 is achieved. Provision is made for mounting the signal on a normal supporting pillar by means of socket 12 (Fig. 2). The area between the red lights 72 (Fig. 5) and the green lights 73 is composed of bulbs arranged in the shape of a " V " (green) and an inverted " V "  (red). Initially, let the red light 72 and the inverted " V " red bulbs be alight. When a change is to be made, the bulbs are switched off in pairs along the inverted " V " from its base to its tip, and just after the last red bulb 88 is extinguished, the red light 72 is put out whilst green light 73 and the green normal " V " bulbs are lit, the cycle then being continued in the same way for a change from green to red. The intermediate bulbs of Fig. 5 may be switched using a timing disc 122 (Fig. 7) which carries fingers 156 to 161 arranged in different planes, a further disc behind it carrying similarly placed fingers but positioned 180 degrees respectively round the disc if the lights are to show for equal intervals and a larger or smaller angle if one light is to be visible for longer periods than the other. Finger 156 engages pronged wheel 132, and rotates wheel 132 so that cam follower 139 rises to the " top " of triangular cam 138 and so switches over a two-way mercury switch 142, hence lighting or extinguishing appropriate bulbs. This switch in one position lights the green bulbs and in the other position the red bulbs when a suitable power supply is connected. The other fingers then operate similar mercury switches in the same way. The finger on the second timing disc reverse these settings of the mercury switches. Fig. 9 (not shown) depicts a suitable wiring diagram for the switching arrangements which may be accomplished continuously or under the control of a vehicle counting mechanism, in the latter case a cam on the timing discs operates a further switch in the power supply circuit (Fig. 6, not shown) or alternatively two switches operated by a single pin (Fig. 11, not shown) may be used. In another switching system (Fig. 10), different length pins 172<SP>1</SP> to 176<SP>1</SP> on a timing disc operate mercury switches via arms 185, 186, and others behind 186, successively, similar pins 178<SP>1</SP> to 182<SP>1</SP> on a second timing disc affecting these switches via arms 192, 195, and others behind 195, in the opposite sense. Pins 177<SP>1</SP> and 183<SP>1</SP> operate the final (e.g. red to green) light change switch via arms 197 and 199.