Low-voltage color tube gun assembly with periodic focusing

One type of color tube, often referred to as the post acceleration color tube, requires a gun of unique design. The gun operates at relatively low voltages of 5000 to 7000 volts as compared with 20,000 to 30,000 volts in other types of color tubes. The tricolor gun assembly described consists of three individual guns arranged in a plane. This limits the inside diameter of the electrodes to 0.358 inch as compared with half an inch or more in conventional guns. The individual guns are either triodes or tetrodes with periodic focusing. In spite of the above mentioned restrictions the spot size is about 0.038 inch at 300 microamperes screen current per gun and 7000 volts anode voltage. The depth of focus is very satisfactory because of small beam diameter.     

A high luminance high-resolution cathode-ray tube for special purposes

For those applications where light sources of high radiance or displays of high resolution are necessary, miniature cathode-ray tubes have been developed with monocrystalline luminescent screens. These newly developed screens consist of cerium-doped yttrium-aluminum garnet (YAG), epitaxially grown on commercially available YAG substrates; they have an excellent heat conductivity and are optically clear. The construction of the tube and its performance in two modes of operation are described. When the tube is operated with a continuous undeflected beam, the luminance of the spot is limited by thermal quenching of the phosphor material. Under these circumstances, the maximum luminance of 1.9 × 10⁸cd/m²(0.55 × 10⁸FTL or 4 × 10⁵W/m²sr) is reached at a power of 70 mW in a 3.5-µA 20-kV beam, focussed to a spot of 9 µm diameter. Equipped with appropriate deflection coils and scanned with an interlaced field of 575 active lines and 25-Hz repetition frequency, the tube can handle up to 20 W of beam power in a 12 × 16 mm²image area. In this mode, the luminance is limited by the design of the electron gun and the desired resolution. At 20 kV and 100 µA (i.e., at 7500 cd/m²) the tube has a half-intensity linewidth of 60 µm, which is equivalent to 500-TV limiting response lines in the same 12 × 16 mm²area.     

大型全平面彩电显像管的技术特点

大型化全平面彩色显像管是近来推出的新管型,因此,所使用的玻屏荫罩、电子枪、偏转线圈及制造工艺等具有不同于普通ＣＰＴ的技术特点,本文对此进行了探讨。     

A high-sensibility cathode-ray tube for millimicrosecond transients

A high-sensibility cathode-ray tube has been developed for the photographic recording of transients in the millimicrosecond region. The new cathode-ray tube uses a traveling-wave deflection system with magnetic focusing and attains a spot diameter of 0.001 inch. The first models have a sensibility of 0.026 volt/trace width and a writing speed of 10¹¹trace widths/second. Improved production models are expected to have sensibilities of less than 0.02 volt/trace width. In this particular application, sensibility in volts per trace width and writing speed in trace widths per second are the significant performance characteristics. Analysis of the dependency of these on several important parameters in the general cathode-ray tube design shows that the use of a much smaller spot and display than is conventional results in large gains in sensibility. Analysis also indicates that maximum sensibility is achieved with the deflection plates located in the lens region. Magnetic focusing is used to permit this optimum deflection plate location. To allow the choice of long plates with short effective transit time, a traveling-wave deflection system is employed. Postdeflection acceleration is introduced to obtain high writing speeds.     

A focus mask for color picture tubes using dipolar and quadrupolar lensing

Post-deflection focus masks can increase the electron-beam transmission in a color picture tube over that achievable by conventional shadow masks. Various focus mask structures are considered here and most attention is given to one in which the electrostatic fields in each mask aperture consist of a dipole and a quadrupole component. A theory of the combination of dipolar deflection and quadrupolar focusing is given. Experiments on small masks are described and their quantitative behavior is evaluated. A demountable focus-mask color tube is described which has a 10-in diagonal flat mask. This has been used to display video and the 50-percent transmission of the focus mask has allowed high brightness operation with screen voltage of only 10 kV.     

Multicolor storage tube

Multicolor storage tubes for applications with low frame rates have been built by modification of direct-viewing storage tubes. A perforated shadow mask is placed between the three writing guns and the storage surface. This shadow mask allows electrons from each writing gun to strike discrete storage areas, each containing a single aperture in register with a color dot on the view plate. In this way, it is possible to write and store electrical signals independently in adjacent color areas. Factors causing color impurity are described, together with the steps taken to minimize their effects. A tube has been built that shows good color purity in a 6-inch-diameter circle; it has 75 total color dots per inch resolution, 8 foot-lamberts brightness, and about 1-minute persistence. Other possible multicolor storage tube designs are discussed.     

The electrostatic storage display tube

The electrostatic storage display tube is a special vacuum tube which combines the intrinsic charge-storage property of a dielectric membrane with the high-speed high-resolution capability of a newly developed electron gun and an independent optical system to provide bright high-contrast large-screen displays. Writing and recording functions have been completely separated from the actual display function, thus providing several advantages over conventional storage display tubes. The same tube may be used for either theater-size displays or hard-copy outputs on photosensitive media. Four phases of the tube are covered in this paper: its basic characterstics, construction, applications, and preliminary speculations on reliability.     

A scan-conversion tube utilizing fiber-optics photon transfer

Scan-conversion tubes utilizing fiber-optics photon transfer (FOPT) are currently being developed by the Westinghouse Electric Corporation under contract from the United States Army Electronics Research and Development Laboratory. The tubes consist of three major components: a reading electron gun, a writing electron gun and an interjacent scan-conversion target. The targets consist of a fiber-optics disc coated on one side with a phosphor and on the other with a photoconductor, the reading gun is similar to the low velocity gun of a vidicon and the writing gun is a high velocity cathode-ray tube gun. The majority of targets tested have incorporated a long storage Permachon type photoconductor and a short persistence phosphor; however, other photoconductors and phosphors can be used to perform a variety of video conversions and/or signal enhancements. Operation of these scan-conversion tubes requires only the circuitry normally associated with the driving of a cathode-ray tube and a vidicon; no RF or other type of cancelling circuitry is required to separate the written and read-out signals.     

The self-heated 442-nm He-Cd laser: Optimizing the power output, and the origin of beam noise

Power output and beam noise parametric results are obtained for the blue transition of the self-heated He-Cd laser in tubes of 0.10-0.16-cm bore diameter. Presentation of this data in the form of performance contour maps shows that the usual scaling laws for laser discharges are accurate for this laser (<12-percent parameter variation for a 60-percent diameter variation) and is a convenient form for use in tube design. The contour maps imply the existence of a direct connection between the output and noise of this laser. A theory is proposed that the noise in the He-Cd discharge arises from the rapid increase in ionization rate due to Penning collisions as Cd is added to the He discharge. This produces a high gain in the discharge column for the growth of striation waves (which modulate the output). The theory correctly predicts the details of the laser noise behavior, showing that both the noise and output share a common origin in the Penning effect. The dependence of Cd vapor density on tube current is found, from sidelight studies, to be more pronounced in self-heated tubes (as opposed to tubes with externally heated Cd sources). A threshold dissipation value is given for puncture of the hot glass bore by the discharge (this is a common failure mode in the He-Cd laser).     

Two-color storage tube

A direct-view storage tube has been developed which is capable of displaying stored information in either of two colors or in intermediate hues. The operating principle is based on the fact that flood electrons which pass through the holes in the storage mask when the storage-surface potential is near cutoff fall within small areas on the viewing screen opposite the storage-mask holes; whereas flood electrons which pass through the holes when the potential is near its maximum, i.e., flood-gun-cathode potential, fall on larger overlapping areas on the viewing screen. The viewing screen consists of a pattern of two phosphors: one occupies small areas in register with the storage-mask holes, and the other occupies areas surrounding the first. The tube, which has a 10-inch diameter, can be operated with simple circuitry, essentially the same as that required for conventional half-tone storage tubes. When the performance of this tube is compared with that of conventional half-tone storage tubes, it can be seen that a moderate sacrifice in resolution was made in order to replace the half-tone monochromatic range with a system of two primary colors and intermediate hues. This system permits the color coding of stored information that provides a vivid qualitative or semiquantitative representation of a variable in the display. The design and performance considerations for the tubes are discussed and future investigations for this type of tube are outlined.     

A high-resolution color CRT for CAD/CAM use

A 19-V color CRT with 64-kHz scanning was developed for CAD/CAM use. A new gun was designed by a three-dimensional phase space method and with the aid of a three-dimensional beam tracing computer simulation. A newly developed oxide cathode was applied to the gun in order to improve the life performance of cathode emission. The spot size at 2 percent of peak was reduced to 0.8 mm at 200 µA. A significant reduction of misconvergence to 0.2 mm was achieved through the use of a small beam-to-beam gun spacing, a new deflection yoke, and a new frittable getter.     

The IRicon: A passive infrared camera tube

The IRicon is an IR-sensitive photoconductive TV camera tube. Recently declassified, it was developed for the military to whom many tubes were supplied in direct-readout or return-beam form with magnetic or electrostatic focus and deflection. Passive imaging of low-temperature objects such as humans or vehicles was observed with a normal TV speed of response. Resolution varied from about 100 TV lines at very low radiation levels to about 500 at higher levels. Scene temperatures denoting less than 1° C from ambient have been detected using f/1.2 optics.     

Investigation of improved magnetic materials for PPM-focused low-noise traveling-wave tubes

Low-noise traveling-wave tubes focused by a combination of a uniform field in the gun region and periodic field (PPM field) over the remainder of the tube usually have a noise figure from 3 to 5 dB higher than those of tubes focused by a uniform magnetic field (PM field). This paper describes how this disadvantage of higher noise has been largely overcome as a result of improvements in magnetic materials and PPM-focusing circuit design. The electrostatic lens effects were reduced by reducing the transverse magnetic field with more uniform magnets and by reducing the period for improved transmission. The magnetic lens effect in the drift region was minimized by extending the length of the uniform gun field so that at least 3 dB of gain occurred in this region. The final tube showed improved electrical and environmental results. A maximum noise figure of 7.9 dB was achieved from 6.4 to 12.0 Gc/s. Noise figures of 6.7 to 6.9 dB were obtained over the 9.2 to 10.2 Gc/s band. The final 5.3 lb low-noise amplifier offers a substantial weight and volume reduction for most low-noise applications and demonstrated compliance with MIL-E-5400F Class 2 equipment specifications.     

Saturated resistor load for GaAs integrated circuits

Saturated resistors, two-terminal load devices, have been fabricated and evaluated as pull-up loads for GaAs digital integrated circuits. The saturated resistor loads exhibit superior device characteristics compared with FET active loads. Up to 100-percent improvement in the uniformity Of the saturation current has been obtained. Ring oscillators with saturated resistor pull-up loads have shown ∼ 20-percent lower speed-power products than ring oscillators with FET active loads. This superior circuit performance is attributed to 1)no gate capacitance, and 2) less backgating effect. Reliability studies using accelerated aging have shown that circuits are more reliable when saturated resistor loads are used.     

A high-resolution electron gun for thermoplastic recording using prefocus deflection

A demagnification gun of high resolution was developed for thermoplastic recording by deflecting the electron beam at the entry of a large focusing lens. The unconventional approach of prefocus deflection allows close spacing between the "short" focusing lens and the target (phosphor screen or thermoplastic tape) required for demagnification and results in a gun with a relatively short length. The diameter of the focusing lens is about three times larger than the 25-mm diameter area to be scanned in order to keep spot distortions of the deflected beam at a minimum. Electrostatic focusing combined with magnetic deflection was selected. The special focusing lens that is used is shaped for low aberrations, increased demagnification and increased deflection sensitivity. Small deflection fields are required since the electron beam is being deflected in the accelerating field while the electron velocities are still low. The gun operates at 10 kv and delivers a 5-micron spot at 1µa. This corresponds to a resolution of 5000 spot diameters at average current densities in excess of 5 amp/cm². In spite of the high resolution, the over-all length of the gun measured from the target is only 9 inches.     

Saturated Resistor Load for GaAs Integrated Circuits

Saturated resistors, two-terminal load devices, have been fabricated and evaluated as pull-up loads for GaAs digital integrated circuits. The saturated resistor loads exhibit superior device characteristics compared with FET active loads. Up to 100-percent improvement in the uniformity of the saturation current has been obtained. Ring oscillators with saturated resistor pull-up loads have shown ~20-percent lower speed-power products than ring oscillators with FET active loads. This superior circuit performance is attributed to 1) no gate capacitance, and 2) less backgating effect. Reliability studies using accelerated aging have shown that circuits are more reliable when saturated resistor loads are used.     

1-Inch Saticon for high-definition color television cameras

A high-resolution 1-in TV camera tube with the Saticon photoconductive layer has been developed for live color image pickup in the high-definition television system based on 2:1 interlaced 1125 scanning lines and 60 fields per second. The inherent high-resolution capability of the Saticon photoconductive target is fully demonstrated by the use of a diode-operation electron gun having no beam crossover point. The electrons emitted from a flat barium-impregnated tungsten cathode are formed into a narrow and laminar electron beam of high current density and low beam temperature using a fine beam-defining aperture about 12 µm in diameter in the positively biased G1disc electrode. The tube has an outstanding resolving power and a low lag characteristic as well as sufficient beam current margin to handle the standard peak signal current of 0.5 µA required for a reasonably highS/Nratio in the wide-band video signal system. The applicability of the design concept to the tubes for standard TV systems is also discussed.     

Noise in traveling–wave tubes

A number of experimental traveling-wave tubes have been built for operation in the 3.2 centimeter wavelength region, and series of noise measurements have been made on these tubes. The periodic dependence of noise figure on the separation between the electron gun and the circuit entrance of the traveling-wave tube has been investigated and various characteristics of these curves have been discussed. A modified noise theory has been suggested; comparisons between it and the experimental results show fair agreement. Noise figure reduction by the use of a triode gun has been investigated for two of the experimental tubes, and a method of analysis that should lead to theoretical justification is suggested.     

Astigmatic electron gun for the beam-indexing color television display

Though the beam-indexing color television display has some obvious advantages when compared with other display systems, the electron-optical demands are very high. First, these demands and the imaging system to be used are discussed. It turns out that the beam must be astigmatic to obtain optimum performance. The beam shape is prescribed by the deflection-coil design. This beam shape, giving rise to a vertically elongated spot of sufficiently small dimensions, is obtained by using an astigmatic gun of special design in combination with a simple rotation-symmetrical focusing lens. After a general discussion of the focusing properties of this combination, the intensity distributions along both the minor and the major axis of the spot on the screen are calculated and compared with experiments. The gamma of the beam current characteristic is measured as well as calculated. Its dependence on the beam current is small up to beam currents of about 3 mA. Moreover, the cathode loading is calculated as a function of the beam current. Without special means of dynamic correction, satisfactory color reproduction in normal picture material is obtained up to peak currents of 1.5 mA in 110°-25 in tubes. Higher beam currents would be attainable in the absence of a residual deflection error which causes a tilt of the spot near the corners of the screen. The structure of the picture is quite acceptable at a triplet pitch of 1.2 mm without using a lenticular screen.