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Overview

Thanks to advanced materials, custom LED blocks, and clever design, PinScore LED displays are far more efficient than any other generic technology display, thereby reducing waste heat and increasing reliability.

The History of Pinball Displays

In 1977 Gottlieb, Bally Mfg. Co, Williams Electronics, Inc. and other pinball machine companies introduced solid state coin operated pinball machines that used the first fluorescent plasma type score display systems. These systems consisted of 5 or more interconnected circuit boards and a vacuum sealed 4, 6 or 7 digit glass tube on each. The individual numerals and, later, alphabetical characters were formed by illuminating an arrangement of segments etched into the tube. The segments were lit by signals from the game computer and powered by a high-voltage (200 volts direct current, or VDC) and low-voltage (5 VDC) power supply.  

At the time, Light Emitting Diodes, or LEDs, were becoming popular. However, the cost, brightness, and efficiency of plasma displays far outweighed that of LEDs, locking in this display technology for over 3 decades. These orange colored, fluorescent plasma displays were designed into hundreds of pinball machine titles through 1990, when the industry switched to the new fluorescent plasma dot matrix style displays that are still in use today. 

30 years later, these pinball machines are still operated in homes and business locations, decades beyond their initial design lives.  LEDs have since surpassed the old plasma display technology in efficiency, brightness, cost, and durability. Coupled with increasing pressure from RoHS (Reduction of Hazardous Substances) legislation in many countries, plasma display technology has effectively become obsolete.  

Today, the engineering challenge is to integrate superior-performing LED system into pinball machines while maintaining the original look and feel of the game. Pinball owners and enthusiasts have long known the viability of using LEDs (Light Emitting Diodes) as an efficient and less expensive substitute for the obsolete plasma displays. LEDs do not require a high voltage power supply to operate. This is an excellent substitute, but requires circuit redesign and custom LED segments in the same font and mechanical format as the original glass tubes.

Power Is Not Free

In order for traditional plasma displays to operate, pinball machines included a dedicated high voltage power supply.  LEDs do not require high voltage, but they do need to get power from a low-voltage supply such as the existing 5V power supply used for game logic.  So, while LED displays eliminate the need for high voltage, an additional load is placed on the original 5V power supply. It is very important not to overload this power supply, or the game will not function at all. A poorly designed display can overload a game's power supply, potentially causing it to fail and damage other components in the game. 

A poorly designed display can overload a game's power supply, potentially causing it to fail and damage other components in the game.

One of the top design priorities in all PinScore systems is low power consumption. Pinball machine power supplies have evolved over the various generations of games. PinScore displays take into account the lowest common power requirements that will work within the design specifications of the affected games. 

Not All LEDs Are the Same 

An LED is an LED, right? Not exactly. There are many chemistries that exist in LEDs with trade-offs in color, power consumption, brightness, consistency, and cost. Traditional stock LED displays use cheaper, more commonly available LED segments (the individual lines that form the letters or numbers) which operate at 20 milliamps (mA) per segment. These LEDs are commonly found in cheaper generic displays.  

PinScore displays, recognizing the need for low power consumption to avoid over-taxing a game's power supply, use custom LEDs manufactured specifically for pinball machine applications. These LEDs use a more modern, slightly more expensive, LED that produces the same brightness as generic off-the-shelf LED segments but with better color rendition and half the power consumption. So, while generic parts use 20 mA per segment, custom PinScore LEDs only use 10 mA per segment. PinScore displays are the only displays available with these advanced LEDs. 

Not All Transistors Are the Same, Either

To operate an LED segment or display, transistors are needed to efficiently switch each segment on and off.  A transistor is a silicon switch that can take a small control signal from the game MPU (Micro Processor Unit) and amplify it into the larget amount of power needed to light a display. Like LEDs, there has been a lot of change in the world of transistors since these games were first manufactured. The original cheap transistors found in these designs are called Bipolar Junction Transistors, or BJTs. These transistors, while well-known and cheap, actually waste a percentage of power when operating. To operate a BJT, an extra milliamp is required. They are also more susceptible to damage from abuse such as short-circuits and over-voltage conditions. 

New transistor designs have been developed since the original Bipolar Junction Transistor.  Today, the Metallic Oxide Semiconductor Field Effect Transistor, or MOSFET transistor is the semiconductor of choice for switching things like LEDs on and off.  While slightly more expensive than its BJT cousin, it uses much less power and is more durable. The MOSFETs that PinScore displays use consume 7 times less power than a BJT and only 0.15 milliamps to turn on.  A typical display can use dozens of these transistors, so the power savings quickly add up.

PinScore vs. Generic Displays

PS-12232-P16

For example, consider a Williams Electronics 16-digit pinball machine LED replacement display with 16-segment alpha-numeric digits.
When this display is "all on", such as when depressing the TEST button, there are 16 lit segments at any given point in time. This is because the display very quickly lights a pair of digits simultaneously. This technique is called multiplexing and saves cabling, simplifies circuitry, and lowers power usage. The scan rate is very high, so the human eye perceives all the digits as lit at the same time.  

PinScore Power Consumption

ComponentCurrentQtyTotal CurrentTotal Power
PinScore Custom LED segment 10 mA 32 320 mA 1.6 W
MOSFET drivers 0.15 mA 34 5 mA 0.03 W
Total

325 mA 1.63 W

Generic LED Power Consumption 

ComponentCurrentQtyTotal CurrentTotal Power
Generic LED segment 20 mA 32 640 mA 3.2 W
BJT drivers 1 mA 34 34 mA 0.17 W
Total

674 mA 3.37 W

This example does not account for other circuit overhead, as the drivers and LED's themselves utilize about 90% of the power.

PinScore displays are over twice as efficent as generic displays. While this example focuses on a more power-hungry display, these types of savings are seen across the entire PinScore product line.

Conclusion

While saving power feels good, helps the environment and takes a slight edge off the power bill, the largest benefit of using a low-power display is protecting the other parts of your pinball machine. The reduced heat output from a low-power design measurably extends the life of other game electronics. By not exceeding the original design specs of the original power supply, PinScore low-power designs will not cause catastrophic damage to the original game power supplies.

 

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