3 Smart end user devices
3.3 Smart glasses

Smart glasses belong just like smart watches among so called wearable devices and integrate a computer and glasses into one device. Required information is provided via integrated display or directly into a picture the user can see via glasses [21]. There exists a specific group - smart sun glasses - glasses which changes their optical (light filtering) properties (tint) according actual lighting conditions. There are several methods how to show a smart glasses user required information:

- via optical head-mounted display (OHMD) - e.g. Google Glass,
- via integration of wireless glasses with a transparent heads-up display (HUD) - e.g. Solos glasses,
- via augmented reality (AR) overlay with a real picture (using mirroring a projected picture) - e.g. Vuzix Blade,
- via a laser that projects a tiny image directly onto the corner of users‘ retina - a new technology introduced by Intel in Vaunt glasses.

Functions which are provided by smart glasses to a large extend depend on purpose they are developed (security, healthcare, entertainment, etc.). Smart glasses can be equipped by wireless technologies such as Wi-Fi, Bluetooth, GPS and mobile network access eventually. For example they can only provide information on glasses screen from a remote system in some cases with audio (they can work like a portable media player). More enhanced glasses can offer a set of mobile applications. Smart glasses can be controlled by buttons, smartphone, voice commands (if a microphone is integrated), gestures or eye motion (if a camera is integrated) and in future maybe by a brain-computer interface (BCI). Like smart watches the smart glasses can also gather data from internal and external sources.

Fig. 12 Examples of smart glasses