Keystroke Sensor: Ambient illumination - Works under all standard indoor illuminations up to 1000 lux Detection rate - Up to 400 characters per minute Detection algorithm - Multiple keystroke support Effective keystroke- Approximately 2mm
Operating surface - Any firm flat surface with no protrusions greater than 1mm
Electrical Power source: Integrated, rechargeable lithium-ion battery (~450 mAH) Voltage - 3.6 Volts Battery capacity: > 120 minutes continuous typing Interface - RS232 serial interface Connector - 4 pin for serial interface + battery charger
Mechanical & Environmental: Dimensions - Approximately 24 x 34 x 90 mm Weight: 160-serial / 80 -BT gram
Temperature: operation 10 – 35 Deg. C Temperature - storage -10 – 75 Deg. C
Certification & Safety: EMC per CE - EN 55024 55022 EN 61000-3-2 -3-3 Laser safety - IEC 60825-1 Class 1 laser enclosure
Step 1: Template creation (Projection Module)
A template of the desired interface is projected onto the adjacent interface surface. The template is produced by illuminating a specially designed, highly efficient holographic optical element with a red diode laser. Note: the template serves only as a reference for the user and is not involved in the detection process. In a fixed environment, the template can just as easily be printed onto the interface surface.
Step 2: Reference plane illumination (Micro-illumination ModuleTM)
An infra-red plane of light is generated just above, and parallel to, the interface surface. This light is invisible to the user and hovers a few millimeters above the surface. When the user touches a key position on the interface surface light is reflected from this plane in the vicinity of the key and directed towards the sensor module.
Step 3: Map reflection coordinates (Sensor Module)
Reflected light from user interactions with the interface surface is passed through an infra-red filter and imaged on to a CMOS image sensor in the sensor module.
Custom hardware embedded in the sensor chip (the Virtual Interface Processing CoreTM) then makes a real-time determination of the location of the reflected light. The processing core can track multiple reflection events simultaneously and can thus support both multiple keystrokes and overlapping cursor control inputs.