Backglass Lights

Before mechanical Score Reels became affordable and reliable enough for universal use, many early Electromechanical machines tracked scores using banks of illuminated bulbs mounted behind the backglass. Each bulb corresponded to a fixed point value — 100, 500, 1,000, 5,000 — and the total visible on the glass was simply the sum of whatever bulbs happened to be lit. Artists designed the backglass paintings around these fixed positions, weaving the scoring indicators into the overall composition.

The backglass light system was elegantly simple: a relay closed, a circuit completed, a bulb lit. No moving parts beyond the relay itself. This simplicity made it cheap to build and easy to repair, though it limited scoring precision and made it impossible to display a running numeric total the way score reels could. Players had to mentally add up the lit positions to know where they stood.

This display style represents a transitional moment in pinball’s evolution — more sophisticated than the pure passive scoring pockets of the pre-electric era, but not yet the mechanically complex reel-based displays that would define the EM golden age. A small number of machines continued using backglass light scoring even after reels became commonplace, typically in budget-tier or novelty designs where manufacturing cost was the overriding concern.