Why a shutter

[taskellusaf]

Why did they put a shutter on this phone... Other cameras work fine without it... This always freezes up. Camera lens is already behind plastic screen.. What other protection do you need.... I

[djtonic]

http://www.steves-digicams.com/knowledge-center/why-digital-cameras-have-mechanical-shutters.html

Mechanical shutters: the bottom line

In layman's terms, a mechanical shutter is used to control how long the pixels on an image sensor collect light. A simple mechanical shutter can be used to turn the entire sensor array on/off during the exposure. This eliminates the need for added electronics at each pixel location that would be used to turn on/off the pixel and store the charge (accumulated light). By using a mechanical shutter, a simpler, less expensive, and more efficient sensor can be used: one that has a higher fill factor (uses more of each pixel to actually capture light). Of course, nothing is ever cut and dried. Some cameras use both a mechanical and an electronic shutter! In these cases, the electronic shutter is used to supplement the mechanical shutter by providing features like a faster flash sync speed where mechanical shutters are just not fast/accurate enough. Most digital SLR cameras that use a mechanical shutter, however, use the mechanical shutter to control the amount of charge accumulated on the sensor as this simple mechanical device can be used to simplify the circuitry on the sensor itself thereby generally improving image quality and reducing noise.