SIC 3671 Electron Tubes

SIC 3671

This category covers establishments primarily engaged in manufacturing electron tubes and tube parts. Establishments primarily engaged in manufacturing X-ray tubes and parts are classified in SIC 3844: X-Ray Apparatus and Tubes and Related Irradiation Apparatus; those manufacturing liquid crystal displays (LCDs) are classified in SIC 3679: Electronic Components, Not Elsewhere Classified; those manufacturing computer terminals are classified in SIC 3575: Computer Terminals.

NAICS CODE(S)

334411

Electron Tube Manufacturing

INDUSTRY SNAPSHOT

Approximately 90 companies were engaged in this industry during the mid-2000s, down by about 40 percent from the number of firms in the late 1990s. This primarily was due to market consolidation. After a period of growth during the late 1990s, the industry was affected by an economic recession, price erosion, and shifting consumer demands. Total shipment values in 2002 were $2.45 billion, down year-on-year by 24 percent. The industry employed 11,489 individuals in 2002, down considerably from 21,656 in 1997. As a result, total payroll costs over the same time period decreased from $726 million to $487 million.

In the mid-2000s, production of new and rebuilt receiving-type electron tubes, including cathode ray tubes (CRT), accounted for just under 75 percent of industry revenues. The other major product group, accounting for approximately 20 percent of shipment values, consisted of transmittal, industrial, and special-purpose electron tubes (except X-ray tubes). The remainder of shipments consisted of electron tube parts.

ORGANIZATION AND STRUCTURE

The two most recognizable types of electron tubes were the ordinary television and computer tube and the once common vacuum tube traditionally used in radios and other electronic equipment. Generally speaking, electron tubes were sealed glass, enamel, or metallic tubes of varying sizes into which electrons were fired for the purpose of displaying images or conducting, transmitting, or multiplying light for nondisplay purposes. Although television tubes and computer displays were the most common products, industry firms also manufactured camera tubes, microwave tubes, Geiger counters, radar screens, and such specialized devices as electron beam (beta ray) generator tubes, klystron tubes, magnetron tubes, planar triode tubes, and tubes for operating above the X-ray spectrum.

Electron tubes varied according to the extent to which they were "evacuated," or emptied of gases and vapors; by the capability and type of the electron source; and by the number and configuration of electrodes they contained. The amount of power used in electron tubes ranged from milliwatts to hundreds of megawatts, and the frequency of operation ranged between zero and ten-to-the-eleventh-power Hertz depending on the type of tube. In general, CRTs operated by playing a beam of electrons of varying intensities over a display surface such as a phosphor screen, which formed patterns of light that took the form of characters or images. The three basic components of a CRT were the envelope, the electron gun, and the phosphor screen. The envelope, which usually was made of glass, was a funnel-shaped element through which the electrons were fired toward the faceplate on the broad end of the envelope. The electron gun was the source of the electrons, which when heated and formed into a beam, were directed to differing parts of the screen by magnetic fields surrounding the envelope. The phosphor screen itself consisted of a layer of phosphor dots that coated the inner surface of the CRT's faceplate. Color CRTs used a screen made up of red, green, and blue phosphors, with an electron gun for each color; monochrome CRT screens employed one electron gun.

In the everyday family "direct view" TV, the face of the picture tube on which the electrons are projected is the same as the screen the viewer sees. In rear-projection TV sets, which became increasingly common in the 1980s, a translucent screen was used against which images were projected indirectly from three small CRTS (one each for the colors red, green, and blue) through a series of mirrors. In the mid-1990s projection TV tube manufacturers were using compact CRTs and lenses with shorter focal lengths to reduce the amount of space taken up by the television box, reducing the size of the once bulky rear projection sets by a third. In contrast to the 4:3 aspect ratio of the standard...

To continue reading

Request your trial

VLEX uses login cookies to provide you with a better browsing experience. If you click on 'Accept' or continue browsing this site we consider that you accept our cookie policy. ACCEPT