The best way to get the bigger picture
Buying a new television used to be easy. TVs, like personal computer monitors, were built around a century-old technology the cathode ray tube or CRT.
Although tube makers introduced innovations, there remained three main choices screen size, brand and price.
In general, they produce excellent bright images with vibrant colours and smooth motion. But large CRT-based televisions are bulky, heavy and power-hungry devices that look increasingly out of date among other digital devices. A traditional 36in television may be more than two feet (60cm) deep and weigh 150lbs (55kg). This, coupled with the DVD film revolution, the gradual shift to high definition (HD) programming in many countries and tumbling hardware prices is increasing demand for large, flat-panel TVs. These digital TVs are mostly designed for the wide-screen format used by HD broadcasters and DVD movies. The choices among high-definition TVs are complex, even bewildering. Some are not strictly speaking TVs at all. Many big flat-panel TVs lack the built-in tuner needed to receive broadcast TV and are designed instead to work with a set-top box or external tuner.
In addition, while most are sold as “HD-ready”, meaning they can display a high definition image when paired with a suitable set-top box or tuner, some are enhanced definition (ED) sets and cost a little less than true HD units. ED will probably end up being a transition technology.
To confuse matters further, there are several ways of building a big flat-panel TV. Most big flat-panel HD sets are based on one of three technologies: plasma, liquid crystal display panels or rear projection microdisplay systems.
Each technology has advantages and disadvantages.
If you want the largest flat-panel TV at the lowest cost, a rear projection TV based on a microdisplay chip technology such as Texas Instruments' digital light processing is probably the best bet. These jumbo systems are ideal for a home theatre where most ambient light can be blocked out. They face competition in this market from DLP-based front projectors souped-up versions of the projector used for a home slide show or corporate presentation.
Rear projection microdisplay sets typically range in size from 42in diagonally to 60in or more and cost about $3,500 for a 50in HD-ready set. TVs based on LCD panels such as those used in notebook PCs are among the slimmest sets available, sometimes just a few inches thick. Generally they produce bright images but often have problems displaying true blacks and are expensive in large sizes.
Typically LCD flat-panel TVs come in sizes ranging from 15in to 50in. A 32in HD-ready set from a leading manufacturer such as Sony or Sharp will cost about $2,800 in the US, though prices are falling rapidly. In Europe and Asia LCD displays already dominate the flat-panel TV market.
Like LCD panels, plasma displays are made up of millions of tiny individual cells capable of producing points of light or pixels. In a plasma display, the cells contain gases that are charged to strike red, green and blue phosphers to produce the image. Plasma panels are not quite as slim as LCD panels but are very bright and crisp, can display excellent HD images and handle fast-paced movement well. They also have a wider viewing angle than LCD panels about 160 degrees compared to an optimum 40 degrees for LCDs.
However, their shiny screens can produce annoying reflections, they use a lot of power and the brightness dims over time. Most leading manufacturers claim their systems could be watched for eight hours a day for 10 years before this would become a problem.Modern sets from leading manufacturers such as Panasonic, Philips, Fujitsu and Samsung have incorporated a number of features designed to minimise the risk of “burn in” by a static image on the screen.
Perhaps the most significant advantage of plasma sets over LCD televisions for the moment is their cost and size.
I have been testing a 42in plasma panel built by AOC (
www.aocdisplay.com), part of Taiwan's giant TPV Technology group, which recently began selling flat screen TVs on the US market under its own name.
The Envision E42W63 packs some impressive features into a slimline case designed to sit on a table or hang on the wall. Among its features, this widescreen TV supports 852 by 480 resolution, comes with picture-in-picture capabilities and is HD TV ready.
The unit was easy to set up. Almost all the input sockets are conveniently and unobtrusively located on the right side of the unit. The set has S-video, composite and standard TV and video inputs as well as a DVI input for use with a personal computer.
That means you can plug a standard or media centre PC into the panel and use it as a super-sized PC display for playing games, watching DVDs or showing digital camera images stored on the hard drive.
Picture quality is very good, particularly with a DVD or satellite receiver as the source. Switching between a standard 4:3 aspect source and a true widescreen source is easy using the infra-red remote control, which is lucky because, like all native widescreen TVs, standard programming looks rather odd if stretched to fit the 16:9 aspect format.
The alternative, if you are stuck with standard definition programming, is to invest in an HDTV up-converter from a company such as ADS Tech
(
www.adstech.com). This $199 electronic box of tricks is actually a video processor that accepts pretty much any type of video input, including standard definition programming and converts it to HDTV quality video dramatically improving image quality in the process. Working together, the AOC flat panel and the ADS up-converter (model HDUP-1500) turned my standard satellite signal into remarkably high quality video.
In spite of falling prices, big screen television will put a sizeable dent in most bank accounts. But like the shift from black-and-white to colour TV, once digital high definition TV viewing is experienced, it is difficult to think about turning back.
挑选大屏幕彩电
曾几何时，买电视机是一件易事。和个人计算机的显示器一样，电视也是依赖已有百年历史的阴极射线管技术，即CRT。
虽然显像管制造商进行了技术革新，但主要选择仍然只有三种，即屏幕大小、品牌和价格。
总的来说，显像管能生成优质明亮的图像，而且色彩鲜艳，动作顺滑。但是，采用显像管的大电视机庞大笨重，而且耗电量大，和其它数字设备相比显得越来越落伍。一台36英寸的传统电视机高约2英尺(60厘米)多，重约150磅(55千克)。这些因素，加上DVD电影革命、许多国家向高清晰度(HD)节目的过渡以及硬件价格的猛跌，使平板式大彩电的需求不断增加。这些数字电视主要为高清晰度电视台和DVD电影所使用的宽屏格式量身定制。高清晰度电视的选择相当复杂，甚至令人困惑。有些根本不是严格意义上的电视。许多平板式大彩电不带接收广播电视所需的内置调谐器，而以机顶盒或外置调谐器代替。
此外，虽然市场上销售的高清晰度电视大多“支持高清晰数字信号显示”(HD-ready)，即配备合适的机顶盒或调谐器，它们可以支持高清晰图像，但有些属于增强清晰度(ED)电视，价格比真正的HD电视略微便宜一点。ED最终可能成为一种过渡技术。
制造平板式大屏幕电视有几种方法，这样一来就显得更加复杂。大多数平板式HD大屏幕电视基于三种技术之一，即等离子、液晶显示面板或背投微型显示器系统。
每种技术各有千秋。
如果你想以最低的价格购买最大的平板式电视，那么基于微型显示器芯片技术的背投电视可能是最好的选择。德州仪器(Texas Instruments)的数字光处理(DLP)就属于这种技术。这些庞大的系统对于能够遮蔽大部分环境光线的家庭影院来说是最理想的。在这个市场中，它们面临来自DLP前投机的竞争。这种前投机是从家庭幻灯及公司演示用投影机改进而来的。
背投微型显示器的大小一般在42英寸到60英寸之间或者更大，一台50英寸HD-ready电视的价格约为3500美元。采用笔记本电脑中的液晶显示器面板的电视是市场上最轻巧的，有些只有几英寸厚。通常，这些显示器呈现的图像十分明亮，但有时在显示黑色时会有问题，而且大尺寸液晶显示器的价格不菲。
通常，液晶平板式电视的大小从15到50英寸不等。索尼(Sony)或夏普(Sharp)等知名制造商生产的32英寸HD-ready电视在美国的售价仍在2800美元左右，不过价格下跌速度很快。在欧洲和亚洲，液晶显示器已主导平板式电视市场。
和液晶显示面板一样，等离子显示器由几百万个能产生光点或像素的单个微小等离子管组成。在等离子显示器中，等离子管中的气体充电后会产生红、绿、蓝荧光粉，进而形成图像。等离子面板不如液晶显示面板轻盈，但十分鲜艳明亮，可以呈现出优质的HD图像，并能很好地处理高速动作。等离子面板的可视角度比液晶显示面板更大，约有160度，而液晶显示器的最佳可视角度是40度。
但是，等离子显示器耀眼的屏幕会产生令人讨厌的反射，而且耗电量很大，屏幕的亮度也会随着时间慢慢变暗。大多数首屈一指的制造商声称，他们的系统在发生屏幕亮度问题前，可以提供每天8小时、长达10年的观看时间。来自松下(Panasonic)、飞利浦(Philips)、富士通(Fujitsu)和三星(Samsung)等知名厂商的现代电视已新增许多功能，以减小屏幕上静态图像产生的“残影”(burn in)现象。
目前，与液晶电视相比，等离子电视最大的优势在于它的价格和大小。
我在对一台由AOC生产的42英寸等离子电视进行试验。AOC是台湾巨头冠捷科技集团旗下的公司，最近开始在美国市场上销售AOC平板式电视。
Envision E42W63将一些令人印象深刻的功能加入了可放在桌上或挂在墙上的细长形机箱中。这台宽屏电视的分辨率达到852 x 480，具有画中画功能，并支持高清晰数字信号显示。
Envision E42W63易于安装。几乎所有的输入插座都位于它的右边，方便而不碍眼。它具有S-video、复合、标准电视和视频输入，以及连接个人计算机的DVI(交互式数字视频系统)输入。
这也就是说，你可以将标准或媒体中心计算机连接到该机，并在玩游戏、看DVD或显示保存在硬盘上的数码照片时，把它当作超大的PC显示器。
它的画面质量很好，尤其是转换来自DVD或卫星接收器的视频时更佳。使用红外遥控器在标准的4:3画面宽高和真正的宽屏来源之间转换相当容易。这一点很值得庆幸，因为和所有的宽屏电视一样，如果把画面拉长以适合16:9的宽高比，标准格式的节目会看起来相当奇怪。
如果你只能收到标准清晰度节目，那么另一个方案是购买ADS Tech等公司生产的HDTV上转换器。这种199美元的电子盒实际上是一种几乎可接受任何类型视频输入的视频处理器，包括接受标准清晰度的节目并将其转换成HDTV质量的视频，在此过程中显著改善图像质量。将AOC的平板式电视和ADS的上转换器(型号为HDUP-1500)结合在一起，就能把我的标准卫星信号变成相当优质的视频。
虽然大屏幕电视的价格一降再降，但它对大多数人来说仍是一笔相当大的开支。但正如从黑白电视到彩色电视的转变，一旦人们体验了高清晰度电视带来的乐趣，走回头路就很难了。
