Rear-projection Television

Rear-projection television or RPTV is a type of large-screen television display technology. Until approximately 2005, most of the relatively affordable consumer large screen TVs up to 100 in (250 cm) used rear-projection technology. A variation is a video projector, using similar technology, which projects onto a screen.

Modern rear-projection television has been commercially available since the 1970s, but at that time could not match the image sharpness of a direct-view CRT. Current models are vastly improved, and offer a cost-effective HDTV large-screen display. While still thicker than LCD and plasma flat panels, modern rear-projection TVs have a smaller footprint than their predecessors. The latest models are light enough to be wall-mounted.

However, the projection technique is much older than this. Projection systems were used in the very early 1950s when it was still impossible to manufacture CRTs with a screen size much over 12 inches. Utilising a 2 inch monochrome CRT driven at a very high accelerating voltage for the size (typically 25 kV), the tube produced an extremely bright picture which was projected via a schmitt lens and mirror assembly onto a semi translucent screen of typically 17 to 19 inches in size. The resultant picture was darker than with a direct view CRT and had to be watched in subdued lighting. The degree to which the tube was driven meant that the tube had a relatively short life. Details of a specific TV set with its optical system can be found here.

Three types of projection systems are used in projection TVs. CRT rear-projection TVs were the earliest, and while they were the first to exceed 40", they were also bulky and the picture was unclear at close range. Newer technologies include DLP (reflective micromirror chip), LCD projectors, and LCoS, has been capable of 1080p resolution, and examples include Sony's SXRD (Silicon X-tal Reflective Display), JVC's D-ILA (Digital Direct Drive Image Light Amplifier), and MicroDisplay Corporation's Liquid Fidelity.

While popular in the early 2000s as an alternative to more expensive LCD and plasma flat panels, the falling price and improvements to LCDs have led to Sony, Philips, Toshiba and Hitachi planning to drop rear-projection TVs from their lineup. Currently, Samsung, Mitsubishi, ProScan, RCA, Panasonic and JVC remain in the market. The bulk of earlier rear-projection TVs meant that they cannot be wall-mounted, and while most consumers of flat-panels do not hang up their sets, the ability to do so is considered a key selling point. On June 6, 2007, Sony did unveil a 70" rear-projection SXRD model KDS-Z70XBR5 that was 40% slimmer than its predecessor and weighed 200 lbs, which was somewhat wall-mountable, however on December 27, 2007, Sony decided to exit the RPTV market. Mitsubishi began offering their LaserVue line of wall mountable rear-projection TVs in 2009.