A projection keyboard is a form of computer

input device In computing, an input device is a piece of equipment used to provide data and control signals to an information processing system, such as a computer or information appliance. Examples of input devices include keyboards, computer mice, scanne ...

whereby the image of a

virtual keyboard A virtual keyboard is a software component that allows the Input device, input of characters without the need for physical keys. Interaction with a virtual Computer keyboard, keyboard happens mostly via a touchscreen interface, but can also take p ...

is projected onto a surface: when a user touches the surface covered by an image of a key, the device records the corresponding keystroke. Some connect to Bluetooth devices, including many of the latest smartphone, tablet, and mini-PC devices with Android, iOS or Windows operating system.

History

optical Optics is the branch of physics that studies the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultravio ...

virtual keyboard was invented and patented by

IBM International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is ...

engineers in 1992. It optically detects and analyses human hand and finger motions and interprets them as operations on a physically non-existent input device like a surface with painted or projected keys. In that way, it can emulate unlimited types of manually operated input devices (such as a mouse, keyboard, and other devices). Mechanical input units can be replaced by such virtual devices, potentially optimized for a specific application and for the user's physiology, maintaining speed, simplicity, and unambiguity of manual data input. In 2002,

start-up company A startup or start-up is a company or project undertaken by an entrepreneur to seek, develop, and validate a scalable business model. While entrepreneurship includes all new businesses including self-employment and businesses that do not intend to ...

Canesta developed a projection keyboard using their proprietary "electronic perception technology." The company subsequently licensed the technology to Celluon of Korea. A proposed system called the P-ISM combines the technology with a small

video projector A video projector is an image projector that receives a video signal and projects the corresponding image onto a projection screen using a lens system. Video projectors use a very bright ultra-high-performance lamp (a special mercury arc l ...

to create a portable computer the size of a

fountain pen A fountain pen is a writing instrument that uses a metal nib (pen), nib to apply Fountain pen ink, water-based ink, or special pigment ink—suitable for fountain pens—to paper. It is distinguished from earlier dip pens by using an internal r ...

Design

laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

or beamer projects visible virtual keyboard onto level surface. It is a modern input device. A

sensor A sensor is often defined as a device that receives and responds to a signal or stimulus. The stimulus is the quantity, property, or condition that is sensed and converted into electrical signal. In the broadest definition, a sensor is a devi ...

or camera in the projector picks up

finger A finger is a prominent digit (anatomy), digit on the forelimbs of most tetrapod vertebrate animals, especially those with prehensile extremities (i.e. hands) such as humans and other primates. Most tetrapods have five digits (dactyly, pentadact ...

movements. Software converts the coordinates to identify actions or characters. Some devices project a second (invisible

infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

) beam above the virtual keyboard. The user's finger makes a keystroke on the virtual keyboard. This breaks the infrared beam and reflects light back to the projector. The reflected beam passes through an infrared filter to the camera. The camera photographs the angle of incoming infrared light. The sensor chip determines where infrared beam was broken. Software determines the action or character to be generated. The projection is realized in four main steps and via three modules: projection module,

module and illumination module. The main devices and technologies used to project the image are a diffractive optical element, red laser

diode A diode is a two-Terminal (electronics), terminal electronic component that conducts electric current primarily in One-way traffic, one direction (asymmetric electrical conductance, conductance). It has low (ideally zero) Electrical resistance ...

CMOS Complementary metal–oxide–semiconductor (CMOS, pronounced "sea-moss ", , ) is a type of MOSFET, metal–oxide–semiconductor field-effect transistor (MOSFET) semiconductor device fabrication, fabrication process that uses complementary an ...

sensor chip and an infrared (IR) laser diode.

Template projection

A template produced by a specially designed and highly efficient projection element with a red diode laser is projected onto the adjacent interface surface. The template is not however involved in the detection process.

Reference plane illumination

An infra-red plane of light is generated on the interface surface. The plane is however situated just above and parallel to the surface. The light is invisible to the user and hovers a few millimeters above the surface. When a key position is touched on the surface interface, the light is reflected from the infra-red plane in the vicinity of the key and directed towards the sensor module.

Map reflection coordinates

The reflected light user interactions with the interface surface is passed through an infra-red filter and imaged on to a

image sensor in the sensor module. The sensor chip has a custom hardware embedded such as the Virtual Interface Processing Core and it is capable of making a real-time determination of the location from where the light was reflected. The processing core may track not only one, but multiple light reflections at the same time and it can support multiple keystrokes and overlapping cursor control inputs.

Interpretation and communication

The micro-controller in the sensor module receives the positional information corresponding to the light flashes from the sensor processing core, interprets the events and then communicates them through the appropriate interface to external devices. By events it is understood any key stroke, mouse or

touchpad A touchpad or trackpad is a type of pointing device. Its largest component is a tactile sensor: an electronic device with a flat surface, that detects the motion and position of a user's fingers, and translates them to 2D motion, to control a Cu ...

control. Most projection keyboards use a red diode laser as a light source and may project a full size

QWERTY QWERTY ( ) is a keyboard layout for Latin-script alphabets. The name comes from the order of the first six Computer keyboard keys#Types, keys on the top letter row of the keyboard: . The QWERTY design is based on a layout included in the Sh ...

keyboard. The projected keyboard size is usually 295 mm x 95 mm and it is projected at a distance of 60 mm from the virtual keyboard unit. The projection keyboard detects up to 400 characters per minute.

Connectivity

Projection keyboards connect to the computer either through

Bluetooth Bluetooth is a short-range wireless technology standard that is used for exchanging data between fixed and mobile devices over short distances and building personal area networks (PANs). In the most widely used mode, transmission power is li ...

USB Universal Serial Bus (USB) is an industry standard, developed by USB Implementers Forum (USB-IF), for digital data transmission and power delivery between many types of electronics. It specifies the architecture, in particular the physical ...

. Bluetooth dongle technology enables the projection keyboard for point to multi-point connectivity with other Bluetooth devices, such as PCs, PDAs and

mobile phones A mobile phone or cell phone is a portable telephone that allows users to make and receive calls over a radio frequency link while moving within a designated telephone service area, unlike fixed-location phones ( landline phones). This radio ...

. The way that Bluetooth projection keyboards connect to devices depends on the specific tablet, phone or computer.

Alternative uses

Apart from simply being used to type, some laser keyboard systems can function as a virtual mouse or even as a virtual piano, such as the crowd-funded iKeybo.

References

{{reflist, 2 Virtual keyboards