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Editor's HDTV Pick

HP 47 inch MediaSmart 1080p LCD HDTV "Out of the box" digital media platform. Enjoy videos, pictures and music from home network + digital media delivered over your broadband Internet connection + 3 x HDMI

Contrast Ratio is an important consideration is the selection of any kind of display device. However, it should not be the prime determining selection criteria - particularly as the viewing environment can severely affect perceived contrast ratio.

What is Contrast Ratio?

Contrast Ratio is the ratio of the brightness between the whitest and blackest areas of a screen determined using a test procedure. The two most common methods of measuring contrast ratio are:

• American National Standards Institute (ANSI) test where a checkerboard pattern of 16 black and white rectangles are displayed. The ANSI contrast ratio is the result of dividing the average light output of the white rectangles by the average light output of the black squares.
• The Full On/Full Off contrast test which measures the ratio of the light output for a white to the light output of an all black (full off) image for the display being tested.

Full On/Full Off tests yield higher results than an ANSI tests. Manufacturers generally quote the Full On/Full off (higher) test results for their products but, mostly do not specify which test was used. It is commonly argued that the ANSI test is more indicative of contrast ratio due to its checkerboard pattern being closer to actual viewing conditions.

Factors Affecting Perceived Contrast Ratio (read more..)

Advances in solid-state light sources (LEDs) which will significantly affect the performance and design of light intensive applications such as, rear-projection televisions (RPTV), automotive headlamps, and commercial lighting were recently announced by Philips Lumileds Lighting Company. Philips Lumileds, a high-volume manufacturer of power LEDs, announced on June 28 that it has established new luminance performance records for solid-state lighting technology at 1 Amp. Among the achievements announced was a white luminance 50% greater than an automotive halogen bulb.

Until the 1990’s, when scientists at Meijo University and Nichia Chemical Industries in Japan produced blue light by using thin films of gallium nitride, LEDs were limited to longer wavelengths (infrared through red to green). LEDs are smaller, sturdier, and more energy-efficient than incandescent lamps and are already used in traffic stoplights, brake lights, and large animated signs.

Sandia Laboratories have believed that a new solid-state white light source could decrease worldwide lighting energy consumption by 50% and total electricity consumption by more than 10%. The United States, Department of Energy (DOE) believes strongly enough in solid-state lighting (SSL) that on June 6 it announced that it is providing a total of US$7 million for five cost-shared projects. (read more..)

The newly released Sanyo LP-XL40, LCD projector is aimed at the education sector. With its distinct “large eye” lens the projector can project an 80-inch (2030 mm) image from just over one meter away (1030mm) and a still respectable 60 inch image from its minimum projection distance of 76 cm away.

To achieve its short throw distance feats the projector uses 11 projection lenses combined with two large aperture aspherical lenses (the big eye). A 200W extra-high pressure mercury lamp provides a lower end 1,500 lumens of illumination.

The Sanyo LP-XL40 uses 3LCD technology - three LCD microdisplay chips of 1024 by 768 pixels. LCD microdisplays are “transmissive” – controlling the light passing through them like a valve by using the polarization effects of the chips liquid crystals. LCD microdisplay projection systems separate the projection lamps light into red, green, and blue light using wavelength (color) splitting dichroic filters The separate light colors pass through the microdisplays and are then recombined to form the full-color image.

LCD microdisplay manufacturers have established the 3LCD Group to promote the technology. Members include Epson, Fujitsu, Hitachi, Sanyo, Panasonic, and Sony. The group promote their LCoS approach and using their 3LCD logo as a counter to the DLP technology brand marketing efforts of Texas Instruments.

LCD chips do not produce as deep blacks as DLP microdisplays but, they are improving their position with technologies such as the use of high-temperature polysilicon (HTPS) LCDs – the basis for the 3LCD projection technology used in this projector. LCD also can have some slight discoloration problems in images that have large white areas.

The Sanyo LP-XL40 digital projector has the bonus feature of horizontal keystone correction allowing the projector to be set up slightly off center without image distortion a bonus in setup flexibility in difficult situations. For further reading on keystone correction see our article on Keystone Correction.

Read our Microdisplay chips for rear projection televisions post to learn more about the new generation of projection technology chips.

SMART Technologies manufacture the Actalyst interactive overlay for large screen plasma and LCD displays for more than 15 manufacturers including NEC, Samsung, LG, Panasonic and Toshiba. Both portrait and landscape orientated models are available for most brands and sizes 32″ to 65″ (81 cm to 165 cm).

Actalyst overlays fasten to LCD or plasma displays to create touch-enabled interactive surfaces. The Actalyst’s DViT (Digital Vision Touch) technology allows users to interact with software, websites and other multimedia content by touching the display surface. Two digital cameras embedded in the overlay’s frame detect and track the position of any contact with the screen. The overlay is designed to be suitable for interactive information kiosks in commercial environments such as retail stores, office buildings, airports, train and bus stations.

Actalyst Flat Panel Overlay Features

• Protective surface: The overlay is glass covered with a hard-coat, anti-glare film for a durable, scratch, abrasion and chemical -resistant surface with a high transparency that does not compromise image quality.
• Universal Mounting brackets: a universal mounting bracket fits in between the flat-panel display and the panel’s specific mounting plate to allow mounting in a portrait or landscape mode.
• Software: The driver software for touch control is available for most Microsoft Windows and Apple Mac OS X operating systems and is compatible with content-development software.

SMART Technologies is currently participating in research being conducted at the FedEx Institute of Technology at the University of Memphis in Tennessee for the interactive kiosk and digital signage markets. The Memphis Intelligent Kiosk Initiative (MIKI) is a research project designed to investigate the preferred and most efficient forms of human interaction with information kiosks. This research should provide excellent data for SMART Technologies to apply to its future products for the developing interactive kiosk market.

Detailed information on the Actalyst interactive screen overlay visit SMART Technologies website.

The following link is a complete list of plasma and LCD displays supported by Actalyst.

Epson’s PowerLite 6100i multimedia projector, announced in June, has been designed with features and performance for universities, conference facilities, and other high-use environments.

The 6100i projects at up to 3,500 ANSI lumens of brightness in XGA (1024 x 768 pixels) native resolution, enabling presenters to display visual content with sharp details and rich colors in higher light level environments.

The PowerLite 6100i features technology that can be used to help address the needs of hearing impaired and colorblind students. The projector is compatible with tuners and components that transmit closed caption content. This facilitates the display closed caption content on a projector without installing extra external components.

(read more..)

Samsung has four, High Definition (1080p), rear projection TV sets; the HL-S7178W, HL-S6187W, HL-S5687W and HL-S5087W with corresponding sizes of 71, 61, 56 and 50 inches. All should produce the same picture quality with the differences being physical sizes and some additional features with the HL-S7178W having some additional features, including a CableCard slot, a TV Guide EPG, two FireWire (IEEE 1394) ports, picture-in-picture (PIP), and an higher performance sound system.

Samsung was the first company to introduce a rear-projection HDTV with a native resolution of 1080p (1920 x 1080 pixels). Their 1080p rear projection range is based on microdisplay technology with a single Texas Instruments DLP chip. The chip has millions of tiny mirrors that switch on and off some 15,000 times per second to create the video output required. This sort of speed is required for delivering sharp pictures for sport and other fast movement video. The range has a contrast ratio of 10,000:1 in line with its peers in the market.

Native High Definition 1080p Resolution

Like other HD televisions utilizing DLP chips, native 1080p resolution is obtained by “wobulation” which doubles the horizontal resolution. This is in contrast to LCoS 1080p displays that have the full 960 x 1080 pixels on the chip.

With wobulation technology, each frame is produced by the projection of two subframes slightly offset (by wobbling the DLP chip micro-mirrors back and forth) in extremely rapid succession. The human eye interprets the result as a single seamless image of higher definition. Wobulation eliminates the ‘screen door’ effect plasma and LCD displays are prone to however, it must be applied carefully so that image sharpness is not reduced.

Picture Technologies

Samsung provides four picture modes (Dynamic, Standard, Movie, and Custom) which can be adjusted for color, brightness, contrast, brightness etc. with each remaining distinct for each input. This facility allows you to customize the picture mode for each video source, for four different lighting environments or other preferences. Samsung has also provided a “Games” mode, which increases color saturation and brightness and adds edge enhancement.

(read more..)

HP have now discontinued their rear projection HDTVs including the two reviewed here however, they have introduced a new line of LCD and Plasma Flat Panels.

Hewlett Packard’s (HP) MD6580 and MD5880 1080p Rear Projection HDTV’s are part of the popular and growing range of lower cost, high definition, rear projection televisions incorporating microdisplays using DLP, LCD, or LCoS technology.

Both the MD6580 (65 inch) and the MD5880 (58 inch) are DLP microdisplay powered with a native resolution of 1920 x 1080 pixels. Image processing is powered by a single Texas Instruments HD4 DLP chip.

Picture Technologies Used

• Wobulation For both models Hewlett-Packard have used their “Wobulation” technology for reducing the cost of high resolution displays. Texas Instruments have a similar technique which is trademarked as SmoothPicture which is used in marketing by some manufacturers. Drawing from their experience with overlaping of printing ink, HP use Wobulation to double the horozontal image resolution from any video source. Each frame is actually produced by the projection of two subframes slightly offset (by the wobbling back and forth of the DLP chip micromirrors) in extremely rapid succession. The human eye interprets the result as a single seamless image of higher definition.
  Wobulation eliminates the ‘screen door’ effect plasma and LCD displays are prone to. However, it must be applied carefully so that image sharpness is not reduced. HP have aspirations of using 4x wobulation for quadruple resolution both horizontally and vertically.
• Dynamic Black DynamicBlack, also a trademark of Texas Instruments, is used in both models for the provision of deeper black levels with improved image detail in darker scenes. A contrast ratio of 12,000:1 is quoted.
• Motion Adaptive Deinterlacing Both HP models also incorporate Motion Adaptive Deinterlacing which detects and compensates for motion in pictures, reducing any contouring and visual noise without affecting picture detail.
• True-to-Life-Color True-to-Life Color is a technology aimed at producing accurate color temperature and warm, natural tones.

Rainbow Effect

Manufacturers of single-chip DLP displays attempt to minimize any “rainbow effect” by using, fast rotational speed, multi-segment color wheels. In this case HP have opted for a seven-segment color wheel. Before making a decision, potential purchasers of single-chip DLP rear or front projection products should always arrange a viewing as although big strides have been made in reducing the incidence of “rainbow effects”, sensitivity varies from person to person.

(read more..)

PolyVision’s Walk-and-Talk Flat Screen Module is not actually a full overlay but a screen module which fits to the bottom of a large plasma or LCD screen. There is a single, universal model which has been designed to be suitable for most plasma and LCD sizes between 37 and 63 inches.

Because it does not cover and protect the display surface, Polyvision recommend that the flat screen module only be used with reinforced commercial grade screens. The advantage is that there is no light transmission loss through an overlay.

After fitting the module to the flat screen a stylus or remote control can be used to access files, run applications, highlight presentation features and capture screen content.

(read more..)

SMART Technologies Inc. produce the SMART Board for Flat-Panel Displays interactive overlay gives you touch control of your display. Once fitted to your plasma or liquid crystal display panel the touch-sensitive overlay allows all the functionalities of an interactive whiteboard including drawing, displaying images and controlling software applications.

The overlay material is an anti-glare polyester which has been hard-coated for scratch resistance and designed for optimum transparency. The SMART Board is available in a large range of sizes from 40 inches to 61 inches.

SMART’s proprietary DViT (Digital Vision Touch) technology uses digital cameras in the corners of the display to track contact with the screen. SMART “Touch gestures” allows users to use hand/finger gestures to mimic mouse functionalities. Scrolling is achieved by touching the overlay with two fingers and dragging them up and down or side to side. Similarly, a right mouse click is achieved by touching a the overlay with one finger then pressing another finger to the right of it. This functionality reduces the time spent searching for the right buttons to press.

(read more..)

Pennsylvania’s Numonics Corporation manufacture the ID42, ID50 and ID60 Interactive Display Touchscreen Overlays for various screen sizes.

The overlays attach to a plasma screen converting it into an interactive (electronic) whiteboard. It’s important that an overlay not significantly cut the light emission from the display beneath. Numonics literature quotes that their overlays absorb only 10% of the light from the covered screen and the viewing angle remains excellent.

Interactive Display (ID) features:

(read more..)