TV Screens: The Couch-Distance Scan
QR codes on TV — in ads, broadcasts, retail displays, and hotel welcome screens — are scanned from 2 to 4 meters by viewers on couches. The screen is emissive, which helps contrast enormously compared to print, but camera sensors interact with screens in tricky ways: moiré interference, refresh-rate banding on some displays, and glare from room windows. And the viewer gets one comfortable attempt before giving up and going back to the show.
The 10:1 Rule of Thumb
At 3 m the rule suggests 300 mm on screen. On a 55-inch TV (about 1.2 m wide), that's a quarter of the screen width — large, but TV codes that actually get scanned are large. As practical guidance, the code should be at least 15–20% of the screen's width for living-room distances. Timid corner codes are the classic TV failure: visible to the designer, invisible from the couch.
Recommended Size
Display at a minimum of 200 mm (about 8 inches) across on the screen for living-room distances; 300 mm for retail displays and lobbies viewed from farther away. Bigger is always safer on TV — the screen is huge, the viewer is far, and there is no print cost to going larger. For broadcast, verify the code survives the station's encoding chain; heavy compression softens module edges.
Substrate and Printing (Digital)
The screen is the substrate. Brightness and contrast settings vary wildly between TV models and user settings, so design for the worst case: full-bright white background, pure black modules, no transparency tricks, no brand-color experiments. What looks elegant in the edit suite must survive a five-year-old TV in eco mode in a bright living room.
Placement and Practical Tips
- Hold the code static for at least 5 seconds — viewers need time to notice it, unlock their phone, open the camera, and aim. Two-second flashes during fast-cut ads are unscannable theater.
- Keep the code clear of broadcast safe-margin edges, channel bugs, news tickers, and subtitles — any of which can crop or overlap it.
- Beware moiré: the camera sensor's grid interfering with the screen's pixel grid creates shimmer on fine modules. Larger modules resist it; dense codes shimmer into failure.
- Center the code rather than pushing it to a corner — extreme side viewing angles distort it, and corners collect on-screen graphics.
- For retail displays, check glare at different times of day; a code that scans at 9am can wash out at 3pm when the sun swings around.
Common Mistakes
- Flashing the code for two seconds during a fast-cut ad — nobody scans in time, and the media spend is wasted.
- Small "elegant" corner codes that are invisible beyond the couch.
- Screen glare from windows washing out the code at certain times of day on retail displays.
- Linking to a page that isn't ready for a traffic spike — TV scans arrive all at once.