Video camera tube

A device that captured images in television cameras.

Video camera tubes were devices that captured images in television cameras. The term was also applied to the technology itself. Introduced in the 1930s, they were used several decades before CCD and fiber optics became popular, as a cheaper alternative to expensive broadcasting equipment.

In these tubes, the cathode ray was scanned across an image of the scene to be broadcast. The resultant current was dependent on the brightness of the image on the target. The size of the striking ray was tiny compared to the size of the target, allowing 483 horizontal scan lines per image in the NTSC format, 576 lines in PAL, and as many as 1035 lines in HiVision.

The lifespan of video tube technology reached as far as the 90s, when high definition, 1035-line video tubes were used in the early MUSE HD broadcasting system. While CCDs were tested for this application, as of 1993 broadcasters still found them inadequate due to issues achieving the necessary high resolution without compromising image quality with undesirable side-effects.

Modern charge-coupled devices (CCD) and CMOS-based sensors offer many advantages over their tube counterparts. These include a lack of image lag, high overall picture quality, high light sensitivity, and dynamic range, a better signal-to-noise ratio, and significantly higher reliability and ruggedness. Other advantages include the elimination of the respective high and low-voltage power supplies required for the electron beam and heater filament, elimination of the drive circuitry for the focusing coils, no warm-up time, and a significantly lower overall power consumption. Despite these advantages, acceptance and incorporation of solid-state sensors into television and video cameras was not immediate. Early sensors were of lower resolution and performance than picture tubes and were initially relegated to consumer-grade video recording equipment.

Also, video tubes had progressed to a high standard of quality and were standard issue equipment to networks and production entities. Those entities had a substantial investment in not only tube cameras, but also in the ancillary equipment needed to correctly process tube-derived video. A switch-over to solid-state image sensors rendered much of that equipment (and the investments behind it) obsolete and required new equipment optimized to work well with solid-state sensors, just as the old equipment was optimized for tube-sourced video.

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Video camera tube
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Adapted from content published on wikipedia.org
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Last modified on May 14, 2021, 8:49 pm
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