Integrated electron sources for multibeam CRT's

Integrated circuit techniques have been used to make accurate multicathode electron sources for use in a new high-resolution multibeam CRT. The device features 16 photolithographically patterned oxide cathodes, a common grid, and an integral heater, on a 3.8-mm-square sapphire chip. The electron sources have adequate saturation currents and precise low cutoff voltages. A demountable vacuum system and an emission microscope that images cathodes on the screen of a CRT were constructed to examine the chip during operation.     

A developmental tricolor vidicon having a multiple-electrode target

Color television cameras which are now widely used require three separate camera tubes to supply the simultaneous primary color information transmitted by the compatible system. This paper describes a developmental tricolor camera tube of the vidicon type for use in a single-tube color camera. The ability to generate the three simultaneous signals is achieved in the tricolor vidicon by means of a multiple-electrode target structure having three interlocking groups of color-sensitive strips connected to separate output terminals for each primary color. A single low-velocity electron beam scans the photoconductive target. No special requirements are made on the beam with respect to focus or scanning accuracy. Registry of the three signals is inherent in the design of the target. The performance of the developmental cameras which have been constructed to date does not equal the three-tube image orthicon camera from the standpoint of sensitivity, color fidelity, and uniformity. In its present state, the tube is potentially useful for industrial and scientific purposes where sufficient light is available and structural defects do not obscure the information desired. To extend its range of application, the development of more sensitive photoconductors and improved methods of fabrication are required.     

New structure GaP—GaAlP heterojunction cold cathode

A negative electron affinity (NEA) GaP-GaAlP cold cathode with a new junction structure is proposed and demonstrated by improved fabrication techniques. Emission efficiencies as high as 0.7-1.1 percent were obtained from these cathodes. The energy distribution of the emitted electrons from the cold cathode had a full width at half-maximum of about 0.3 eV. A resolution of about 500 TV lines was obtained with a sealed off 1-in vidicon tube having the cold cathode and an Sb2S3target. The electron beam temperature was about 650 K. At present, highly stable and long life NEA cold cathodes can only be obtained by improving the activation method. It is proposed that the NEA p-GaP surface can be stabilized by a Cs, Sb, and O2activation.     

Experimental investigations and numerical simulation of the electron flow shaped by Grigor’ev-Shesterkin matrix carbon field-emission cells

The results of the investigations of the electron flow in Grigor’ev-Shesterkin field-emission cathode cells intended for use in microwave tubes are presented. It is shown that it is possible to develop electron-optical systems (EOSs) with field-emission cathode matrices for O-type microwave tubes whose beam emittance is similar to the that of the EOSs with grids and hot cathodes.     

Emission reserve mapping of CRT-type cathodes

The "dip test" was recommended in 1956 to evaluate the emission activity of cathodes, and this method is now in common use for evaluation of cathodes in microwave tubes and in other electron devices wherein unvarying geometry and field configuration permit simple application of the test and interpretation of results. Application of the "dip test" to CRT cathodes, however, involves complexities associated with a) variation of emission current density from center to edge of the cathode, b) variation of the emitting area and current density with intensity modulation (grid voltage), and c) variation of the grid-cathode geometry which takes place during the cooling period of the dip test. A method has now been developed for accurately evaluating the cathode activity for varying radii of concentric circular cathode areas. A figure of merit is introduced which characterizes the cathode emission.     

电泳法制备场发射阴极的性能优化研究

电泳法是一种新型的大面积碳纳米管场发射阴极制备方法。文章在成功地用电泳法制备了适用于场发射显示器的碳纳米管阴极基础上,通过选用不同的碳纳米管原料、改变电泳条件等方法,进一步优化碳管阴极的性能。使用不同方法制备的碳纳米管配置电泳液,由于制备方法和碳管本身的特性,管子在电泳溶液中呈现不同的分散性。碳管管径较粗时由于表面自由能相对小,所以碳管在溶液中不易形成团聚物,电泳沉积的阴极会均匀平整;管径小的碳管则由于容易团聚,需要加入表面活性剂来改善其在电泳溶液中的分散性。场发射特性和发光显示图实验结果发现,即使得到相同均匀平整的阴极,但是由于碳管本身的发射能力的差异性最终导致电泳沉积得到的阴极的场发射特性的不同。另外,电泳的实验条件也会对沉积的阴极的场发射性能和形貌产生影响。在不同电泳直流电压条件下,碳管薄膜的密度分布和厚度不同,呈现出不同的场发射能力,结果表明当电压值在25V时可以得到性能最佳的场发射阴极。     

CCD camera for dual-energy digital subtraction angiography

A motion immune dual-energy subtraction technique in which X-ray tube voltage and beam filtration were switched at 30 Hz between 60 kVp (2.0 mm Al filter) and 120 kVp (2.00 mm Al+2.5 mm Cu filter) was previously reported. In this study the effects of camera lag on the dual-energy iodine signal is investigated. The temporal lag of the lead oxide vidicon tested reduced the dual-energy iodine signal by a factor of 2.3, as compared to a mode that included 4 scrub frames between low- and high-energy images, for an iodine phantom with thicknesses of 0-86.0 mg/cm(2), imaged over a 15 cm thick Lucite phantom. On the other hand, the Charge-Coupled Device (CCD) camera has inherently no temporal lag and its versatile scanning characteristics make it near ideal for dual-energy DSA. The CCD camera eliminates the reduction of dual-energy iodine signal, since it does not mix low- and high-energy image data. Another benefit of the CCD camera is that the separation time between low and high-energy images is not limited to the frame period, as is the lead oxide vidicon; and as small as a 5-msec time difference is possible. The short time interval between low and high-energy images minimizes motion misregistration artifacts. Due to these advantages, the CCD camera significantly improves the utility of dual-energy DSA.     

Use of auger spectroscopy in the evaluation of thermionic cathodes

The ability of Auger spectroscopy to identify chemical species existing on a surface has been used to evaluate the properties of "good" and "poor" impregnated tungsten cathodes used in high-power microwave wave tubes. The surfaces of "good" and "poor" cathodes were studied by means of Auger spectroscopy and work function measurements and the results interpreted to analyze failure modes in cathodes removed from TWT's because of poor emission characteristics. Most of the poor cathodes evaluated in this program were obtained from fabricated electron guns that had been employed and discarded from the 200-W TWT tubes developed for the Communication Technology Satellite (CTS) program. The results of these measurements have shown there are at least two types of failure modes that one observes with poor cathodes. They are 1) chemical contamination of the cathode surface and 2) low partial layer barium coverage of the cathode surface.     

Submillimeter imaging with a pyroelectric TV camera

The use of a TV camera with a standard pyroelectric tube for imaging continuous submillimeter (submm) waves is described. The spectral sensitivity of such pyroelectric vidicon has been measured. The results of experiments on diffraction and interference using submm laser radiation are presented. For the first time, submm images of different objects have been obtained with the aid of a pyroelectric vidicon. It has been shown that a pyroelectric TV camera can be effectively employed in various laser studies as well as in submm imagery technique.     

Large-signal transient analysis and effects of lateral charge spreading in television camera tubes

The transient response of television camera tubes to changing levels of illumination is examined. When the entire transient occurs within the exponential retarding potential region of the electron beamI-Vcharacteristic and photoconductive lag can be neglected, exact analytical expressions describing the rise and decay of video signal levels are established. The author present separate solutions to the problem based on the assumptions of electron beam scanning and charging by a hypothetical defocused beam (uniform charging case). The results support arguments in favor of target current biasing to minimize lag and turn-on time. We also show the effects of scanning as opposed to continuous dwelling by a flood beam. The decay transient is shown to be universial in the sense that it is independent of the initial signal strength and depends only on physical tube parameters. The validity of the expression describing signal decay is confirmed experimentally for a silicon diode array vidicon and a return beam silicon diode array vidicon. The effect on the resolution of target surface conductivity in conjunction with a finite electron beam impedance is treated for a steady-state per pattern and isolated circular spot illumination. In particular, the strong dependance of resolution, as limited by a conducting target surface, on operating current level is described. Lateral target leakage is shown to offer little advantage in decreasing lag.     

基于热阴极的相对论返波管电子枪设计

近年来热阴极特别是钪系阴极得到充分发展,有望成为高功率微波的电子源。提出一种基于热阴极的新型“面包圈”式电子枪模型,以此电子枪作为相对论返波管的环形电子束发射源。通过仿真软件CST PARTICLE STUDIO对模型进行仿真验证,所得电子枪发射电流为786 A,阴极发射电流密度为30 A/cm2,电子束密度为305 A/cm2,电子通过率为99.9%。最后对热阴极在高功率微波器件中的应用进行了初步探索。     

Secondary electron conduction (SEC) for signal amplification and storage in camera tubes

Previous studies^1,2of the electrical properties of thin-film low-density deposits of insulators have led us to investigate their application as electrostatic storage targets. It was found that the charge image on the target is not only established by transmitted secondary electrons but that the backward conduction of secondary electrons through the layer also contributes to the amplifying mechanism. Free electrons created by the incident primary electron which are normally not observed as emitted secondary electrons can be conducted through the voids of the low-density layer to the target signal plate under the action of an electric field. This mechanism leads to an efficient conversion of photoelectrons with several kev energy into a large number of positive charge centers on the surface of the layer which are accessible to a low-energy reading beam. The secondary electron conduction (SEC) effect provides, therefore, high target gain while solid-state time lag does not occur. The high resistivity of such layers, many orders of magnitude greater than that of insulators in bulk form, is advantageous for long-time integration and storage. The target has a large storage capacity useful not only to provide a wide dynamic range, but also to accommodate the more intense signals required for low contrast image detection. The capacity is small enough, however, to eliminate discharge lag. Compatibility of the SEC target with standard photosurfaces, such as S-11, S-20, and various ultraviolet sensitive types, has been demonstrated in sealed-off tubes. The performance of SEC vidicon tubes is reported, and it is concluded that the SEC target offers the potential of overcoming several limitations found in present day camera tubes.     

HB2电子枪中空间电荷效应的研究

以阴极射线管(CRT)为例,研究了在不同发射电流下空间电荷效应对荧光屏上电子束点大小的影响。研究结果显示,当阴极电流大于1mA时,空间电荷效应开始起显著作用,而当阴极电流小于1mA时,空间电荷效应的影响逐渐减小,以致可以不考虑。此外,除了空间电荷效应最严重的阴极区外,主透镜区和漂移区的空间电荷效应相对预聚焦区较为显著。     

MCRT的特点及其扫描电路的设计

ＭＣＲＴ是一种多枪结构的ＣＲＴ，是大屏幕扁平ＣＲＴ的经典模式之一。它是由多个小尺寸（如１０厘米左右）的ＣＲＴ，采用低熔点玻璃粉的封接技术，做成一个具有较大显示面积（如大于１００厘米）的ＣＲＴ。ＭＣＲＴ具有一些优良的特性如；较大的显示屏幕，较小的厚度、良好的电子束光点，较高的亮度和对比度以及较高的分辨率等，它非常适合于户外使用。ＭＣＲＴ的整幅图像是由一些单元图像所组成的，拼接的图像往往会在单元图像之     

The application of semiconductors with negative electron affinity surfaces to electron emission devices

Semiconductors with negative electron affinity (NEA) surfaces are used as photoemitters, secondary emitters, and cold-cathode emitters. A comprehensive review of the characteristics and applications of these materials is presented, the concept of NEA is described, and a comparison is made between NEA and conventional emitters. Electron generation, transport, and emission processes of NEA emitters are discussed. NEA III-V compound photocathodes, especially GaAs, are described with respect to their fabrication, performance, and applications to photomultipliers and image intensifier tubes. The structure and performance of NEA secondary emitters are presented. NEA GaP secondary-emission dynodes represent the most important device application. NEA cold cathodes, using GaAs, Ga(As, P), or Si, have been investigated, and their performance characteristics are summarized. NEA Si cold cathodes have been incorporated in developmental TV camera tubes. The characteristics of these tubes are reviewed.     

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.     

Silicon phototransistor vidicon

The use of silicon phototransistor arrays as high gain targets in vidicon camera tubes is shown to provide a sensitivity advantage. An analysis of device operating parameters indicates that signal enhancement can be obtained during both the write and read portions of an array element's duty cycle. Maximum effective signal amplification is secured by choosing a design which recharges the collector-base storage capacitance mostly during the read interval. Expressions for the effective signal gain in terms of transistor common base current gains and elemental capacitances have been derived, and the effects of phototransistor operation on vidicon sensitivity, image persistence, and dynamic range have been considered. Experimental transistor arrays have been fabricated and have been used for the first successful demonstration of phototransistor signal gain under the usual conditions of vidicon operation. Signal gains exceeding 70 have been recorded.     

测量热阴极次级发射特性的扫描电子探针法

本文介绍了一种适用于量测热阴极次级发射特性的扫描电子探针法,原电子探束束斑直径为50100m,束流小于10-7A,原电子能量不大于3kV。该装置能定点测量热阴极表面上感兴趣点的次级发射系数与原电子能量间的关系曲线(-Ep);也能以扫描方式在短时间内测出整个热阴极表面的次级发射分布,从而求得次级发射的定量分布曲线(f-)。该装置在电视制式的扫描方式工作时,能观察热阴极表面的次级发射图象。 对纯镍样品的测量表明:该装置具有比单枪定点法更多的优点和更高的精度。由于该装置简便灵活,便于与热阴极研究的特殊需要相结合,因此,可望在热阴极的研究中发挥作用。     

Activation process-dependent characteristics of novel thermionic oxide cathodes for CRT application

The emission and conductivity characteristics of oxide cathodes depend largely on the activation process. In this paper, the electrical properties of new type of oxide cathodes for cathode ray tube (CRT) application, supplied by LG Philips Displays, have been investigated in relation to different cathode activation regimes. The influence of the activation process over different durations has been investigated. A temperature of T=1425 K was chosen to be higher than the optimum cathode activation temperature (T=1200 K), and the other temperature of T=1125 K was lower than that. The electron activation energy (E) was found to vary in the range from 0.58 to 2.28 eV for cathodes activated at the higher temperature regime, and from 1.08 to 1.9 eV for those activated at the lower temperature regime. Scanning electron microscopy (SEM) and electron diffraction X-ray (EDX) analyses show a structural phase transformation in the oxide material that was activated at 1125 K for a period of 1-12 hours. The SEM mapping shows a large contamination of Ba in the top layer of oxide material. The activator agents tungsten and aluminum are found to penetrate into the BaO/spl bsol/SrO layer in two different ways.     

A cyclotron resonance frequency multiplier

The current density available from known thermionic cathodes imposes a serious limitation on the power output obtainable from electron tubes operating at frequencies above about 10 Gc. This paper describes a proposal for a frequency multiplier which has the interesting property that the RF energy imparted to the electron beam by the signal source may be one or two orders of magnitude greater than the dc energy supplied by the battery. Thus it is expected that the power output at a particular frequency will be much higher for a given cathode current density than that obtained from conventional types of electron-beam oscillators and amplifiers. The multiplier operates by converting the input energy at one radio frequency into rotational energy of an electron beam by means of a Cuccia coupler. The beam then couples power to the output load via a multicavity circuit containing2ncavities wherenis the frequency multiplication to be obtained. The paper includes details of experimental work on a low-power tube multiplying from 600 Mc to 3600 Mc. In this tube 1.3 watts of RF input power is coupled on to a 50 volt, 260-µa beam and the power at 3600 Mc is coupled out via a 12-cavity magnetron anode structure. Photographs are given of the trace of the rotating beam impinging on a fluorescent screen and these demonstrate the degree of focussing achieved along the length of the tube. The paper concludes with a study of the feasibility of a tube multiplying from 10 Gc to 100 Gc with an output of tens of watts.