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Direct View (CRT) Format
Today there are several kinds of HDTV color television display device formats. The most common had been the cathode ray tube (CRT) and had been found for HDTV in flat, wide-screen picture tube sets with 36-inch diagonal screens and smaller. In the HDTV configuration, the larger wide-screen CRT is referred to as Direct-View, the term mentioned in the last chapter. This distinguishes this format from the 60+-inch diagonal rear-projection format, the LCD display device format, the DLP display device format, the Plasma display device format, and the larger projection area reaching 120-inch diagonal when a ceiling-mounted front projection format is used to create the on-the-wall or large screen home-theater experience. There was even a front-projection format sold during the beginning of the large-screen projection television era, where three bright CRT tubes were fit into an area that was aimed up at a large curved projection screen, the entire piece produced as one bulky unit. This allowed the CRT's convergence to be maintained if the set was moved around in the home. But that was in the 1980's before wide-screen HDTV viewing came of age. The big advantage of the HDTV Direct-View set was that it didn't run into convergence problems of the red, green, and blue colors such as with projection sets as they gradually aged, electronic settings changing values displaying blue, red, or green edges that become more evident as the eye moves from the center out towards the four corners. Also, the Direct-View CRT did not need to run as hot because it does not reply on mirrors to see its image, and hence its name "Direct View." These single picture tubes will last for years, if not decades.
The disadvantage of the larger Direct-View sets was that they can be extremely heavy, limiting them to smaller diagonal screens than other formats. The weight was created from the massive amount of glass that is used in the front in the manufacture of these larger picture tubes, a set of 32-inch diagonal or larger requiring two people to move it . . . unless one of them is a large gorilla. However, current pricing for HDTV Direct-View screens is no longer available from retailers, manufacturers moving on beyond the Direct-View format and now focus entirely on the other HDTV formats for obvious reasons. These sets had run about $550 for a 26-inch diagonal screen to a 32-inch diagonal model for $600 to $900 depending on features. See Chapter 1 if you want to review charts on how a CRT creates a picture inside its glass surface.
Allow me to take a moment to explain the importance of the diagonal-screen measurement, which I have adhered to throughout this report having worked in the electronics industry for 20 years. First, the standard establishes a benchmark from which all other screens can be measured and more importantly, compared. This provides a consistency when researching the screen size of different manufactured television sets, no matter what the format. Secondly, because it's diagonal, the screen size does not yield the actual width of the cabinet that holds it. That's why a 27-inch diagonal television set may seem actually slimmer in width even when thin-panel speakers are mounted into the side of the chassis. With control panels kept at the bottom or top of the set, minimal widths are then achieved for television monitor-only configurations and home television sets where the speakers are mounted to the side and behind the wide part of the CRT. However, these sets should not be mounted into a vertical cabinet for permanent viewing where the cabinet's sides are solid and no wider than the set. That because the audio will be muffled and the intended surround-sound effect you might have heard on the sales floor will disappear. However, television manufacturers understood that their units might be placed in these configurations, and why they placed a speaker On/Off Switch usually under the front control panel. Having the switch in the Off position allows the sound that is routed to an external home stereo system, via the set's audio output jacks located on the rear, to be the only sound heard in the room. With the television's speaker turned Off, it eliminated any hollow sound coming out of the close-fitting enclosure, an unwelcome addition to an otherwise clean stereo sound. While you may see audio jacks on front on television sets (and VCR's too) or behind clever tiny doors in the front of chassis, these jacks will almost always be in three's and intended as audio inputs (red and white), not outputs, the third jack being a video input (yellow). This triad of input jacks is used for easy and fast connection of external video and audio sources that may come from portable components such as a camcorder or games, allowing quick setup and playback of recorded tapes for awaiting family or friends or playing games temporarily on the home's main television. Some direct view sets (such as 19-inch diagonal to 32-inch diagonal) offered a jack pack on the rear of their set that includes component 480i signals for outputs from the new DVD players and digital cable boxes. HOWEVER, be aware that every video input needs a separate audio input. Last year we had come across a 25-inch diagonal flat-screen television for $169 in a discount store, with a known brand name. We were amazed to find 480i component inputs along with video and left and right audio inputs. We had also hoped for a S-VIDEO input, but that would have not mattered in this jack configuration. Why? Because in today's availability of sophisticated add-on components, this television set would only have been able to accommodate a DVD player or a digital cable box, not both unless you were willing to sacrifice picture quality by resorting to the RF input on the television. That's because there was only one set of stereo input audio jacks on this set. Therefore, if you used the component inputs from a DVD player, you couldn't use them from your digital cable box. The same true with an S-Video input. There is only one set of audio input jacks. To run a 480i component output from a cable box, a 480i component output from a DVD player, and a similar signal from another component with an S-Video output, you would need THREE sets of audio input jacks, as each picture input needs separate audio inputs to match. Yes, there is an RF jack that includes the audio in its signal. But who wants to watch at best 330 lines of resolution when you can increase the clarity on the screen with S-Video and component inputs. So again, if you want to have digital cable and a DVD hooked up with component input jacks to your new direct view television, look for at least two sets of stereo audio input jacks on the back of your set when it's on the sales floor. If you see only one, move on! Oh, one other thing. If you had a stereo system you wanted to feed using this new discounted television, "forget about it!" There were no stereo audio output jacks. Of course, when using a stereo system tied to your television, for best results the audio out signal should always be tied to the volume of the television set. That way you are adjusting the volume for both systems at the same time when changing the volume on the TV using your remote control. Controlled audio outputs are only good for recording audio when matching the pre-amp audio input signals on tape and digital recorders. These systems need a fix signal to work properly that will match their inputs, which is an industry standard I believe of around one volt peak-to-peak. ___________________________________ |
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Index
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