Computer screen

Status: ⚠️ marginal — poor contrast / refresh

A computer screen is a VLL emitter that flashes a black/white area of a monitor or tablet in the VLL timing while the brick's sensor is pressed against it. It needs no hardware, but it's a hobbyist experiment, not an official period method — LEGO's 1999 Micro Scout was filled via a Scout / RCX or the IR tower, not a screen.

Limitations

• Worse contrast and latency than a torch.
• Timing is limited by refresh rate: 60 Hz = 16.7 ms/frame (too coarse for 20/40 ms bits); 120 Hz phones do better.

Pre-baked video variant

A flashing video encodes the on/off timing in its frames, so playback has no runtime jitter. It is still bounded by display refresh.

Best for

Experiments without any gear; expect lower reliability than torch/LED.