What are Some Guidelines for Electronic Message Center Resolution?

A critical aspect of any sign is viewing distance. The appropriate amount of detail varies greatly, depending on the distance from which the sign will be viewed. In digital printing, this “resolution” is determined by “dots per inch,” or DPI. The more closely an image will be viewed, the higher its resolution needs to be, which means the dots produced by the inkjet printer would need to be closer together, and there would be more of them within a defined space.

The same concept applies to electronic message centers. The individual LEDs function the same as the inkjet dots. The more detail you want, the more LEDs you would need with a defined space, and the decision would be based on the anticipated viewing distance. An electronic billboard 600 feet from the highway is different than an electronic message center built into the cabinet of a freestanding pole sign next to a two-lane road.

For electronic signs, this resolution is called “pixel pitch,” and it means the distance between the centers of individual LEDs, which are known as pixels. The distance also varies if the individual pixel is color (comprising different-color LEDs) or monochrome (one color). Here are some general guidelines for pixel pitch and viewing distance.

Pitch Range Viewing Distance
3-6mm up to 50 feet
6-12mm 50-100 feet
12-15mm 100-200 feet
15-20mm 200-400 feet
20-30mm 400-800 feet
30-40mm 800-1500 feet
More than 40mm More than 1500 feet

As for the size of letters and viewing distance, the standards for non-electric signs apply similarly — approximately 1 inch of letter height for every 50 feet of distance from which it would be viewed. This should be coupled with the speed of traffic. Allowing a viewing time of 20 seconds is ideal. Thus, if a car is traveling at 60 mph, the sign should be legible from a distance of 1734 feet. Generally, electric highway signs should be a minimum of 10 x 30 feet.

An article on this topic appeared in the May 2004 issue of Signs of the Times magazine.

Penn State Study Provides Optimum Lighting Levels

Illuminating signs, including electronic message centers (EMCs), at inappropriate lighting levels hurts everyone. If the LEDs that light the sign aren’t bright enough, then the sign won’t be legible at night, and the sign loses its nocturnal value. The energy used to light the sign is wasted.

Conversely, if the LEDs are lit too brightly, everyone also loses. The “sometimes more is less” axiom holds true, because when signs are lit too brightly, they become illegible. Plus the excessive brightness upsets people. Excessive energy use is coupled with ineffectiveness. Additionally, when LEDs are lit to intensities in excess of their intended use, their lifetime is exponentially shortened. And, once again, energy is wasted.

So, what is the “just right” illumination level?

The United States Sign Council commissioned The Thomas D. Larson Pennsylvania Transportation Institute at Pennsylvania State University to make this determination, specifically for LED illumination, in 2015. USSC has been working with Penn State (PSU) since 1996, and this collaboration has subsequently produced 18 research projects directly related to optimum usage of on-premise signage.

PSU surveyed EMC manufacturing companies and asked their opinions about optimum lighting levels, but there was no consensus. Nor did prior research on the subject produce a consensus. So PSU set up two EMCs on its track at the Larson Institute and 48 licensed drivers (an equal number of males and females). They read two words in 12-in.-tall letters from a distance of 360 ft. in eight sign-color combinations.

Full study here.

University of South Carolina Professor Asks Business Owners to Evaluate their Electronic, Changeable-message Signs

Hendrikus E.J.M.L. van Bulck is an Assistant Professor of Business Administration at the University of South Carolina Sumter. He teaches marketing, entrepreneurship, small-business management, financial management, accounting and strategic management. He is also a partner in Van Bulk Partners, CPAs, LLC, where he is responsible for corporate planning and business valuations.

Van Bulck surveyed the 36 Sumter businesses that had programmable, electronic, variable-message signs (EMCs) for their businesses.  The businesses included 20 retail stores, five gas stations, six service-oriented businesses, five fast-food restaurants, five pharmacies and three banks. Here are some of their observations:

  • More than 85% of the respondents said the EMCs “helped bring in more customers”, and 25% “strongly agreed.”
  • 83% said the sign “measurably increased sales.” 17% “somewhat disagreed,” but no one “strongly disagreed.”
  • 89% agreed with the statement, “The LED sign makes people more aware of the location of the store.”
  • Only 8% said “Customers found such signs unattractive.”
  • 92% said the signs “were easy to update.”
  • 89% would “recommend the sign to other businesses.”

Study: The Value of Signs

Formal Report: Details