An input/output expander for a mobile device has a communications module connectible thereto. Output display signals from the mobile device and input signals to the mobile device are relayed between the mobile device and the bi-directional projection unit by the communications module. A display output projector is connected to the communications module, and the output display signal from the mobile device is converted to a first series of light outputs corresponding to the output display signal. The expander has a virtual keyboard projector generating a second series of light outputs corresponding to a virtual keyboard key arrangement. A key input sensor with a sensing coverage area encompassing the virtual keyboard key arrangement detects user input at specific positions thereon. A key input value corresponding to a specific key of the virtual keyboard key arrangement is generated.