Kahn turned to Mr. Schlafly, director of television research at Fox.
“I said it was a piece of cake,” Mr. Schlafly told the Stamford Advocate newspaper in 2008.
He installed a motorized scroll of paper inside half a suitcase. Actors’ lines were printed on the paper in half-inch letters, and the suitcase was set up next to studio cameras. The scrolling speed was controlled by a stagehand.
“We tried at one time to have the speaker control the speed,” Mr. Schlafly told the Advocate. That idea went nowhere, he said. “It was like patting your head and rubbing your stomach.”
Gambling that they would find customers for their invention, Barton, Kahn and Mr. Schlafly quit their jobs to start a new company, TelePrompTer Corp.
They introduced the device in 1950 on the CBS soap opera “The First Hundred Years,” and it soon became a standard accouterment for live broadcasts, such as “The Tonight Show” and “The Ed Sullivan Show.”
The company’s breakthrough came in 1952, when former president Herbert Hoover inaugurated the teleprompter as a politicians’ tool in a speech before the Republican National Convention. At one point, Hoover interrupted his script to improvise. When the teleprompter paused, Hoover panicked and, under his breath, urged that the scrolling resume.
The moment was observed by hundreds of reporters, and their stories served as free advertising. “We must have gotten 10,000 newspaper clippings from around the world about Hoover using the prompter,” Mr. Schlafly once recalled. “That got us into the public- speaking business.”
TelePrompTer Corp. served as a consultant to at least five political conventions. The company developed an all-in-one convention podium, which came with a prompter, plumbing to deliver drinking water and an elevator to give shorter speakers a lift.
Refining the prompter concept, the company eventually replaced the conspicuous suitcase unit with glass panels placed on either side of the speaker — a familiar sight to anyone who’s watched a State of the Union address in recent decades.
Later, the company’s Lens Line Prompting System superimposed words in front of the camera, allowing a speaker to look directly into the lens while reading a speech.
In ensuing decades, others refined and updated the teleprompter concept, developing computerized text and software that scrolls automatically at the speed of a speaker’s sentences.
TelePrompTer, meanwhile, branched out into the nascent cable television business. By 1970, it had become the country’s largest cable company.