Dr. Reiffel (it’s pronounced like rifle) was an inventor with dozens of patents, but the Telestrator resonated the most.

For the broadcaster John Madden, the device was transformative, greatly enhancing his ability to describe what the 22 men on the football field were doing, especially the linemen battling at the line of scrimmage during a running play. As a former coach, Mr. Madden used the Telestrator at CBS Sports, then at other networks, to let viewers in on the sort of explanations he had given to his players.

“You needed to identify the players with illustrations, not just words,” Mr. Madden said in a telephone interview on Tuesday, recalling what he might say when he used the Telestrator to draw up a play: “Watch this guy — he’s going to go here, and this guy’s going to come up from here and collide here, and the running back is going to go between them.”

Mr. Madden could be sloppy with his Telestrations as well as fanciful, sometimes using the tool to comically point out the Gatorade buckets on the sidelines, or the Thanksgiving turkey that he was going to eat after a game.

“I wasn’t trying to do art,” he said.

Dr. Reiffel’s forays into television, including one as the host of a local children’s science show in Chicago, had inspired the Telestrator. He had grown frustrated with the limits of narrative voice-overs to describe what was being shown onscreen, and, he told Popular Mechanics in 2009, “I decided it would be very nice to be able to get my hands in the picture and draw on it.”

The earliest version let Dr. Reiffel draw with a stylus on a transparent plastic sheet that was placed over a TV screen. It was coated so that electric currents could run over it. An image combiner merged the signals from the camera and pens.

The device was first used successfully with weather reports, prompting Dr. Reiffel to approach the CBS station in Chicago about expanding its use into sports. The CBS network eventually embraced it for N.F.L. games.