23-02-2011, 12:01 PM
Virtual-Keyboard.doc (Size: 1.67 MB / Downloads: 209)
1. INTRODUCTION
In computer systems, the actual processors, are more likely to become outdated than to actually wear out. But there are parts of a computer system that are more susceptible to wear and tear. Understandably, these are the parts that receive the most use – the parts that you pound on each day. Yes, keypad is likely to wear out long before the rest of your computer system.
As the technology advances, more and more systems are introduced which will look after the user’s comfort. Few years before hard switches were used as keys. Now-a-days soft touch keypads are much popular in the market. These keypads give an elegant look, they give a better feel.
They are dust-proof and has got much more life than the other keypads. Thus we see that the new technology always has more benefits and is more user-friendly.
We are presenting here a next generation technology in this area, which is the Virtual Keypad. As the name suggests the virtual keypad has no physical appearance.
There is a frame which is empty or filled with air. The area inside the frame is divided into small equal areas, each representing a key. When the user wants to press a key, what he has to do is simply place his finger at the appropriate position in the frame, in other words on the virtual keypad and the desired key will be pressed.
Infra Red Theory
Infrared (IR) radiation is electromagnetic radiation whose wavelength is longer than that of visible light, but shorter than that of terahertz radiation and microwaves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light with the longest wavelength. Infrared radiation has wavelengths between about 750 nm and 1 mm, spanning three orders of magnitude. Humans at normal body temperature can radiate at a wavelength of 10 micrometres.
Overview
Infrared imaging is used extensively for both military and civilian purposes. Military applications include target acquisition, surveillance, night vision, homing and tracking. Non-military uses include thermal efficiency analysis, remote temperature sensing, short-ranged wireless communication, spectroscopy, and weather forecasting. Infrared astronomy uses sensor-equipped telescopes to penetrate dusty regions of space, such as molecular clouds; detect cool objects such as planets, and to view highly red-shifted objects from the early days of the universe.
At the atomic level, infrared energy elicits vibrational modes in a molecule through a change in the dipole moment, making it a useful frequency range for study of these energy states. Infrared spectroscopy examines absorption and transmission of photons in the infrared energy range, based on their frequency and intensity.
2. LITERATURE SURVEY
Infrared are the waves having frequencies higher than the red light frequency. Thus the input to the IR transmitter should be a frequency. The infra red rays have the heating effect.
The frequency can be generated from any astable multivibrator which generates continuous pulses. These pulses cannot be fed directly to the IR transmitter as the current capacity is very low of such oscillators. Thus to increase the current capacity amplifiers are required. So a simple transistor as an amplifier can be used to strengthen the signal. The IR transmitter is to be placed in the collector path so that the amplified current is passed through the IR transmitter. The duty cycle should be greater than 50% to achieve the best results.
To avoid any interference from other IR emitting sources such as heaters, signal bits are modulated with a stable 30-40kHz carrier frequency and transmitted using an IR diode.
The IR signal is detected and demodulated by TSOP1738, which is a photo detector and preamplifier in one package that demodulates IR signals. Thus any remote signal with a carrier frequency close to 38 kHz can be detected and decoded. The output of the IR detector is high/low corresponding to the incoming IR signal.
Fundamental Differences Between Microprocessors & Microcontrollers
1. Microprocessors are intended to be general purpose digital computers where as Microcontrollers are intended to be special purpose digital controllers.
2. Microprocessors contain CPU, memory, Addressing circuits & interrupt handling circuits. Microcontrollers have these features as well as timers, parallel & serial I/O and internal RAM & ROM.
3. Microcontroller models vary in data size from 4 to 32 bits. 4-bit units are produced in huge volumes for very simple applications, and 8-bit units are more versatile. 16 & 32-bits units are used in high speed control & signal processing applications.
4. Many modes feature programmable pins that allow external memory to be added with loss of I/O capability.
Existing Keypad / Keyboard
No one has to stick with the standard keyboard that comes with the computer. There are many options to consider. Your choice of keyboard is a very personal matter.
1.Projection Keypad
Projection keypads or virtual keypads claim to provide the convenience of compactness with the advantages of a full-blown qwerty keyboard. These are not real keypads, but virtual ones that can be projected on any surface. The ‘Keypad’ tracks the finger movements and processes that information to decipher the intended keystroke. Such systems can also function as mouse. One of the players in this area is Canseta with their Electronic perception system.
2. Canseta keypad
1. The Integrated Canesta Keypad is based on a controller and two optical components that project the image of a keypad onto any flat surface and use a light source to track the movement of fingers on that image.
2. Electronic Perception Technology
3. Made up of three components.
2. Pattern Projector is used to project light onto a flat surface, forming a keypad layout or a custom layout of your choosing.
3.2. An IR light source bathes the keypad in an infrared light.
Sensory module picks up finger movements over the keys. The information picked up is formed into a 3D image with motion and translated into standard keypad input data.
3. Roll-up Keyboard
Great for traveling!
Roll-up for easy storage
Dust and moisture proof
Windows® compatible
CE and FCC tested and approved
Standard 104 keyboard
Lifetime: 15,000,000 keystrokes