# Smart Glasses Viewing Area Management How smart glasses use radio tags on each device and a viewing cone to show captions only while the wearer faces the TV\. By Joy Sargis Topic: Computing, AI & Electronics [Open the interactive Jig](https://ask.jig.com/j/VQkioThF3bee) ## Transcript ### 1. Captions that know where you look Maya is watching a film with captions shown inside her glasses\. When she turns to chat with Sam, the words switch off by themselves\. Let's find out how her glasses know when to show them\. Drag anywhere to look around the room\. Caption glasses help people who are deaf or hard of hearing follow speech and sound\. ### 2. A tiny screen in clear lenses The words appear in a small glowing window low in each lens\. The rest of the lens stays clear, so Maya still sees the room and the TV\. The green lines in front of her face show what the window displays\. One caption glasses model has a 30 degree display window and weighs about 43 grams, roughly as much as a slice of bread\. ### 3. Every screen wears a tag A small radio tag sits on the TV and another on the smart speaker\. Each tag shares three things: who it is, where it is, and how big its viewing area is\. That way the glasses can keep track of several devices at once\. A tag could even clip onto a speaker's microphone, so a person can become a caption source too\. ### 4. Finding a tag by radio The glasses send quick radio pulses and listen for the reply\. The time a pulse takes to travel tells them how far away the tag is\. Three small antennas on the frame hear it at slightly different times, which tells them which direction it is in\. This kind of radio is called ultra\-wideband\. An active tag can be located to within about 2 centimetres\. ### 5. The viewing cone The blue cone spreads out from the TV tag into the room: this is the TV's viewing area\. The gold wedge shows where Maya's lenses are pointing\. Captions appear only when she sits inside the cone and her lenses face the TV\. The cone's real size is set by each tag\. The angle drawn here is an example\. ### 6. Turn to talk, captions stop Maya turns to say something to Sam\. She is still inside the TV's cone, but her lenses no longer face the TV\. So the glasses switch the captions off and her view of Sam stays clear\. Some designs can dim or shrink the words instead of switching them off\. ### 7. Many devices, many cones Each tagged device has its own cone and its own stream of captions\. Slide to turn Maya's head and watch which device she is facing\. Captions follow the device her lenses point at, and stop when she faces Sam, who wears no tag\. ### 8. Glance back, words return When Maya looks back at the TV, her lenses face it again inside its cone, and the captions return straight away\. Nobody has to press a button\. The glasses simply follow where she chooses to look\. The same rule works for a TV, a speaker or a person, each with its own cone\.