Screens+and+VDU's

TFT-LCD Thin film transistor liquid crystal display (TFT-LCD) is a variant of liquid crystal display (LCD) which uses thin-film transistor (TFT) technology to improve image quality (e.g., addressability, contrast). TFT LCD is one type of active matrix LCD, though all LCD-screens are based on TFT active matrix addressing. TFT LCDs are used in television sets, computer monitors, mobile phones, handheld video game systems, personal digital assistants, navigation systems, projectors, etc. Liquid crystals currently marketed inside displays are generally non-toxic

Pros:
Cons: = = = Overhead projector  = = An overhead projector is a variant of slide projector that is used to display images to an audience. = ==  Mechanism  An overhead projector typically consists of a large box containing a very bright lamp and a fan to cool it. On top of the box is a large fresnel lens that collimates the light. Above the box, typically on a long arm, is a mirror and lens that focusses and redirects the light forward instead of up. ==  Transparencies are placed on top of the lens for display. The light from the lamp travels through the transparency and into the mirror where it is shone forward onto a screen for display. The mirror allows both the presenter and the audience to see the image at the same time, the presenter looking down at the transparency as if writing, the audience looking forward at the screen. The height of the mirror can be adjusted, to both focus the image and to make the image larger or smaller depending on how close the projector is to the screen. Interactive Whiteboards An interactive whiteboard (IWB), is a large interactive display that connects to a computer and projector. A projector projects the computer's desktop onto the board's surface where users control the computer using a pen, finger or other device. The board is typically mounted to a wall or floor stand. They are used in a variety of settings, including classrooms at all levels of education, in corporate board rooms and work groups, in training rooms for professional sports coaching, in broadcasting studios and more. Uses for interactive whiteboards include: General Operation The interactive whiteboard (IWB) device is connected to a computer through a wired medium such as (USB or a serial port cable), or via a wireless connection (Bluetooth) and 2.4 GHz wireless which is more secure. A device driver software is usually installed onto the attached computer where it enables the interactive whiteboard to act as a Human Input Device (HID), like a mouse. An image from the computer is then projected onto the interactive whiteboard surface from a digital projector connected to the host computer's video output. The user can calibrate the system (align the pointer with the image) if necessary, and activate programs, buttons and menus as they would with a mouse. For any text input that is needed the user can either invoke an on-screen keyboard or utilize handwriting recognition. These input options circumvent the need to return to the computer to enter text into programs. The combination of mouse and keyboard emulation allows the user to control the computer display almost exclusively from the Interactive Whiteboard. To maximize the interaction opportunities, most IWBs are supplied with software that provides tools and features specifically designed to enhance the use of the IWB. These generally include the ability to create virtual versions of paper flipcharts with pen and highlighter options and in some cases virtual tools such as rulers and protractors and compasses to emulate traditional classroom teaching tools. Sample Exam Questions Identify four features of an interactive whiteboard. [4]   1.    2.    3.    4.    Identify 4 disadvantages of LCD screens. [4]   1.    2.    3.    4.
 *  Very compact and light
 *  Low power consumption
 *  No geometric distortion
 *  Little or no flicker depending on backlight technology
 *  Not affected by screen burn-in
 *  No high voltage or other hazards present during repair/service
 *  More reliable than CRTs
 *  Can be made in almost any size or shape
 *  No theoretical resolution limit
 *  Limited viewing angle, causing color, saturation, contrast and brightness to vary, even within the intended viewing angle, by variations in posture.
 *  Bleeding and uneven backlighting in some monitors, causing brightness distortion, especially toward the edges.
 *  Slow response times, which cause smearing and ghosting artifacts. Modern LCDs have response times of 8 ms or less.
 *  Only one native resolution. Displaying resolutions either requires a video scaler, lowering perceptual quality, or display at 1:1 pixel mapping, in which images will be physically too large or won't fill the whole screen.
 *  Fixed bit depth, many cheaper LCDs are only able to display 262,000 colors. 8-bit S-IPS panels can display 16 million colors and have significantly better black level, but are expensive and have slower response time
 *  Input lag
 * <span style="margin: 0cm 0cm 0pt; mso-list: l0 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Dead pixels may occur either during manufacturing or through use.
 * <span style="margin: 0cm 0cm 0pt; mso-list: l0 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Not all LCD displays are designed to allow easy replacement of the backlight
 * <span style="margin: 0cm 0cm 0pt; mso-list: l0 level1 lfo2; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Cannot be used with light guns/pens
 * <span style="margin: 0cm 0cm 0pt; mso-list: l1 level1 lfo3; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Operating any software that is loaded onto the connected PC, including web browsers and proprietary software
 * <span style="margin: 0cm 0cm 0pt; mso-list: l1 level1 lfo3; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Using software to capture notes written on a whiteboard or whiteboard-like surface
 * <span style="margin: 0cm 0cm 0pt; mso-list: l1 level1 lfo3; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> Controlling the PC, markup (annotating a program or presentation) and translating cursive writing to text (not all whiteboards)
 * <span style="margin: 0cm 0cm 0pt; mso-list: l1 level1 lfo3; mso-margin-bottom-alt: auto; mso-margin-top-alt: auto; tab-stops: list 36.0pt;"> In some instances, the Interactive Whiteboard may be provided with an integrated Audience Response System so presenters can carry out polls and quizzes and capture the feedback on the Interactive Whiteboard

Sample Exam Answers Identify four features of an interactive whiteboard. [4]   It is touch-sensitive It is connected to a digital/data projector . . . and a computer The projector displays the image from the computer screen onto the board The computer can be controlled by touching the whiteboard . . . by hand/using a special pen The whiteboard can be used as an electronic flip chart/dry wipe board [1] for each of four points [4] Identify 4 disadvantages of LCD screens. [4]   Limited viewing angle, causing color, saturation, contrast and brightness to vary, even within the intended viewing angle, by variations in posture. Slow response times, which cause smearing and ghosting artifacts. Modern LCDs have response times of 8 ms or less. Fixed bit depth, many cheaper LCDs are only able to display Dead pixels may occur either during manufacturing or through use. Not all LCD displays are designed to allow easy replacement of the backlight. Cannot be used with light guns/pens [1] for each of four points [4]