Tedium - Party In The Rear 📺

Today in Tedium: These days, it’s common to see a TV set that averages around 50 inches or larger—massive enough to be the centerpiece of every living room. But in earlier eras, huge screens like that were hard to come by. Good luck getting that 32-inch CRT up a flight of stairs. What, were you just supposed to lift that 200-pound monster on your own? While not much could be done about the weight of those massive tubes in the days before the LCD panel, there was another trick TV manufacturers had at their disposal: They could simply blow up a smaller tube onto a bigger screen. Today’s Tedium talks about the rise and fall of the rear-projection TV, the one your uncle had because he liked watching football. — Ernie @ Tedium

A rear-projection TV, living out its retirement next to a bunch of old stereo equipment. You can tell it was a very recent model because it’s 16:9 rather than 4:3. (Wikimedia Commons)

The secret to a good rear-projection TV is all in the mirrors

You remember how, in the early 1980s, companies like Sony started making portable televisions? These portable TVs, the best known of which was the Watchman, didn’t use LCDs—rather, they used CRTs that shot the electrons onto an angled screen.

Most TVs shoot those electrons straight on, but portable CRT-based TVs simply didn’t have the room, hence the vertical placement of the electron gun.

Despite their size, their general design was eerily reminiscent of some of the earliest CRTs. The difference was, however, that it was out of necessity, not creative packaging. In the 1930s and 1940s, we had not perfected the art of the cathode ray tube. At first, the picture tubes themselves were often extremely narrow, but often quite long, which sometimes required the CRT to sit at an angle even to properly fit in the television set, as seen in this 1941 patent filing by Philco. That meant, if we wanted screens large and imposing enough to fill a room, we needed a strategy to magnify the screens on the tube.

Enter the projection television, which could expand the screen by expanding the image through practical optical techniques. As a 1937 technical manual from Philips put it:

The disadvantage of the extremely small picture normally obtained on the fluorescent screen can be remedied by making an enlarged projection of this picture. Projected television pictures of satisfactory definition and brightness measuring up to about 100' by 120 cm can be obtained by using small high-power television tubes in conjunction with a suitable optical system for enlargement. In ordinary rooms where the space available for an audience is comparatively small, the size of the projected picture should not exceed 40 by 50 cm. The best distance from which to view the projection screen is between five and ten times the width of the picture. Larger pictures are liable to be too large, considering the space available in the average room.

This sort of projection took two forms: the first, a physical projector that spat a two-foot TV onto a bare wall or specialized screen. (Amusingly, some early wall-projection sets looked kind of like bongs.)

The second model, meanwhile, amplified the picture on the CRT through optical tricks. This type of TV, called a rear projection TV, is the model most reminiscent of the portable television, displaying images via multiple mirrors. The CRT was placed vertically inside the box, pointing down at a concave mirror that further reflected the image into a secondary mirror, which then presented the image through a screen. The chamber of the device is largely empty, with the tube projecting the action onto a mirror. That mirror would then reflect onto the big screen in the widescreen format.

(The concave mirror approach was also used for projection televisions that shot images on walls, by the way, as this 1938 patent filing by RCA shows. They just aimed outward rather than inward.)

The Philips projection television receiver, center, was the first of its kind. (Wireless World/Internet Archive)

The first example I can find of a rear-projection set, per former Philips employee and electronics historian Pieter Hooijmans, was the TEL6, which was developed around 1936 and 1937, and was used as the test model for the “Philips Television Caravan,” a trailer that transported the television experience across Europe so consumers who didn’t own a TV could get an up-close experience with the set. It was also displayed at Radiolympia, a CES-style event for the radio and television industry that took place in the United Kingdom in the 1930s. At the 1937 event, the Evening Standard described a television set with “quite a small cathode ray tube capable of producing a picture brilliant enough for projection on a flat screen measuring 20ins by 16ins.”

Given that everyone else was using straight CRTs, the projection approach was an eye-opener.

But its initial release was not meant to last. Per Hooijmans:

Despite the fact that the set was removed from the show after only three days, a number of sets seem to have been sold, produced and delivered to customers. Unfortunately, most of these had to be recalled due to field failures, with Philips even offering to reimburse the cost. The reason for all of this was the extremely short life time of the MS 11/1 projection tube. This was partly due to the high currents and voltages at which it was operating, and partly due to its sensitivity to breakdown. As soon as something would be wrong in the frame of line deflection drivers, the result would be a horizontal or vertical line that would burn into the picture tube phosphors and destroy the tube.

Philips’ work on this set, led by the company’s Mullard Labs in London, was significant. Ultimately, though, it only saw limited release, in part due to timing. Television, as a concept, completely lost its footing amid World War II in Europe, for obvious reasons.

The RCA-owned patent highlighting how rear-projection works.

In the meantime, this allowed American companies, particularly RCA, to start developing their own versions. In 1945, RCA employees Horace R. Jones and Edward W. Wilby filed for a patent for an “Image Projection and Viewing Apparatus.” The device, similar to the Philips device, uses mirrors to scale the image on a small CRT. Per the patent filing:

Various systems and arrangements for viewing television images in enlarged forms have heretofore been suggested and many of the prior art suggestions have proven useful in some degree. However, for the most part, the arrangements of the prior art have not satisfied the conditions of compactness, coupled with efficient and satisfactory operation, particularly from the standpoint of providing high detailed image viewing. Also, prior art systems have not been of the type which would permit the use of a rigid, planar viewing screen capable of being located, in the operating or useful position, in such manner that all portions thereof are maintained rigidly in the focal plane of the image projecting optical system and are yet capable of being moved wholly within a viewing region.

The present invention has, as one of its objectives, that of providing a television image projection and viewing construction and cabinet by which enlarged images of high definition may be observed.

The process that the RCA 648TPK, an early rear-projection TV, used to display a CRT image on a larger screen. (via Internet Archive)

This concept ultimately saw release as the RCA 648TPK, for which a whole technical service manual exists on the Internet Archive. One notable addition to the set not included in the Philips model was the use of corrective lenses, which effectively helped with the optical fidelity of the reproduced image.

Since a large spherical mirror by itself will not produce an in focus image, the corrector lens must be employed to bring the image to focus at all points on the screen. The spherical mirror and the forty-five degree mirror are front surfaced mirrors to prevent ghosts which would occur from reflections at the surface of the glass of a rear surfaced mirror.

So, given all the work that these big manufacturers put into rear-projection TVs, why wasn’t this the model that ultimately took over? Simply put, cathode ray tubes got a lot better. Manufacturers figured out ways to make the tubes wider and shallower, and to fit in more settings. (See the Watchman example we cited above.) And that meant all this complicated smoke and mirrors to get a reasonably-sized TV screen wasn’t necessary.

At least for a couple of decades.

The television that changed everything for the big-screen TV.

Why rear-projection TVs ultimately made a comeback in room-filling form

If one thing is made clear about rear-projection TVs of the 1930s and 1940s, they looked nothing like the sets you’re possibly familiar with. Those sets were essentially slightly larger versions of the CRT screens. But more modern sets, of the kind that became popular in the latter decades of the 1980s and 1990s, tend to have a distinctive look: They were about as wide as a loveseat, and often sat on the floor, rather than on a stand, as was common in the 1980s and 1990s.

An Advent Videobeam ad that makes a case for its multi-color projectors.

It took us a while to get there. First, the external projector made a comeback via multi-lens devices, starting with the Advent Videobeam. The Videobeam, a giant CRT alternative complete with a projector, cost $2,500 in 1972 money (an eye-watering $19,148 today), but still managed to lose its creator hundreds of dollars on every sale. The projector, notably, used three separate lamps to produce their high-quality color displays—and didn’t have a way to focus the set, instead requiring owners to place the projector in a specific spot to get an optimal image. (This, said the manufacturer, was intentional, because it kept the price of the device down.)

It wasn’t perfect, but it (along with the general interest in home-theater setups) was an excellent sign that TV owners wanted something bigger than what a standard CRT could offer. Soon enough, projector setups were seen as the bee’s-knees when it came to home-theater experiences.

And that became the harbinger that the market was finally ready for rear-projection television.

The harbinger that the rear-end projector was about to make a comeback in a big way came around 1978, when General Electric, a major TV manufacturer at the time, entered the space with the Wide Screen 1000. The room-filling device seemed to have furniture built into its 37-inch screen, but like a Cray supercomputer that you could sit on, it was built for form and function. See, unlike most televisions of the time, the relatively modest CRT was located to the right of the screen. It would then be funneled through a lens onto its giant screen, and then displayed on the giant screen.

The fact that GE was interested in doing this, per Popular Science, was a sign that this was about to become a mainstream phenomenon. GE went with the rear-projection setup, after years of companies selling home-theater nerds on front-projection options, because that’s what consumers wanted. The result was huge TV that was way thinner than comparable options of its era.

“The 1000’s cabinet depth is similar to that of many 25-inch console sets. But a look inside reveals there’s no super-size picture tube magnet,” the publication’s John Free wrote. “It’s all done with mirrors, two special lenses, and a GE 13-inch in-line picture tube.”

The GE Wide Screen 1000, that weird beast of television, ultimately wasn’t where the concept landed long-term. Internally, many rear-projection televisions favored multiple CRTs displaying portions of the images in different colors, which were then blended together on the screen with a giant mirror. In other words, later sets worked like a combination of the Advent Videobeam’s multi-color projectors and the GE Wide Screen’s mirror-redirection.

By the mid-1980s, according to the Chicago Tribune, nearly 200,000 projection sets sold annually, at a price between $1,500 and $4,000—making for at least a $300 million subsector of the TV market. And while two-piece projectors were initially the most popular option, rear-projection sets eventually became the norm.

By the early 1990s, rear-projection sets, while still niche, had gone mainstream off the back of the general interest in large sets above 27 inches in width.

A 1997 commercial for Toshiba’s Theater View TV sets.

Companies like Sony, Toshiba, Hitachi, Mitsubishi, Zenith, and other, made these devices, which had a few notable tendencies: Many of these devices were wrapped in fiberboard in the back like a cheap cabinet, rather than plastic. They tended to use the additional size to have better speakers. The screens weren’t as bright as traditional CRT options.

And the screens were generally a little fuzzy for obvious reasons: One, you were combining three light sources into one, creating a risk of calibration issues. And given that you were pushing light around with analog methods like mirrors, it meant you were effectively resizing electronic images through practical means. Projecting small images onto big screens had its limits.

Gradually, LCDs took over, but even when they did, rear-projection still had a play to stay in the game, at least for a while. Digital light processing, a color technology first developed by Texas Instruments in 1987 and frequently used in movie theaters, started to emerge in rear-projection televisions in the mid-2000s. It was seen as a less-expensive alternative to the then-expensive displays used by large flat screens. They still projected images using mirrors, but they didn’t use CRTs to do so.

An NBC News piece from the era noted that rear-projection screens based on DLP, while still larger and bulkier than the alternatives, offered many advantages of plasma and LCD technology without the price premium:

Digital Light Processing rear-projection TVs have emerged as the star of the middle market. Thanks to DLP, consumers who recoil at the price of a large flat-screen TV can actually walk away with one from Best Buy or Circuit City Stores without ending up in credit counseling. For instance, Samsung's 50-inch-wide HDTV plasma screens go for about $7,000 at Best Buy, while a 50-inch Samsung DLP costs about $3,500. Pioneer's 50-inch plasma TV, which goes for $10,000, may make DLP seem downright reasonable.

Additionally, LCD-based rear-projection sets, made by Sony, were also drawing attention for a while, and even outpaced DLP. For a while, the pitch for these two types of sets seemed to work. They were better than CRTs and cost less than LCDs. As Sound & Vision put it in 2007:

Rear projection sets aren’t getting as much attention as they did even a year ago. They aren’t sexy. You can’t hang them on the wall. But the secret is that you can get performance that can come close to or even match, size-for-size, most flat panels on the market for a lot less money.

Ultimately, the sets were still bulky, and once LCD sets hit scale, it was impossible for rear-projection sets, which had many more internal parts, to keep up. It was the ultimate example of a bridge device—a technology that got us through a moment, only to be surpassed almost immediately.

These days, you can get a pretty good 55-inch TV, better than a rear-projection set in basically every way, for less than $300. Outside of dial-up modems, it may be the most defeated device in tech history.

But hey, for a while, it was the best option.