Hard-vacuum pyroelectric vidicon: suitable materials

A new mode of operation of the pyroelectric Vidicon is reported. This mode does not require a soft vacuum and the tube is operated hard. Requirements for suitable pyroelectric materials are discussed and the results of experiments operating in this mode are presented.     

Alternative pedestal generation scheme gives flickerfree pictures from a pyroelectric vidicon chopper camera

An alternative way of generating the pedestal current in a pyroelectric vidicon (p.e.v.) is described. The better uniformity of the pedestal current gives less flicker when the p.e.v. is used in the 25 Hz chopper mode. A more uniform tube response is expected, being useful when temperature measurements, based on the local video level, are made.     

Mathematical model to describe vidicon operation

A theoretical development is presented that describes the operation of a vidicon. Output current is determined for an arbitrary distribution of intensity and wavelength of illumination falling on the face of the vidicon. The nonlinear behavior of the photoconductor is taken into account. The effect of progressive erasure of the stored charge on the rear of the photoconductor with the motion of the electron beam is included. The readout beam is assumed to be Gaussian with either a circular or elliptical cross section. The effect of the electron beam on lines other than that being scanned is included. Variation in electron beam spot size across the face of the vidicon is also considered. Correlation with published output data is presented. The apparent phase shift of objects, especially at high beam currents, can be significant. Numerical results for the cases of line and sinusoidal targets are discussed in detail.     

Infrared television: performance of pyroelectric vidicon at 8 to 14 ?m

The performance of a television camera using the 2.54cm pyroelectric vidicon has been measured and compared with an analysis that attempts to identify the factors limiting the performance of the system.     

Performance of the pyroelectric vidicon for thermal imaging in the 8—14 micron band

The performance of a television camera using the one-inch pyroelectric vidicon has been measured. The results are compared with an analysis which attempts to identify the factors limiting the performance of the system. Two modes of operation are considered; chopping the incident radiation with a shutter and panning the camera. The measurements indicate that the camera panning mode produces the better performance. At low spatial frequency a scene temperature difference of 0.2°C may be detected.     

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.     

Multifrequency operation of a quenched-domain mode Gunn-effect device

The theoretical influence of harmonic signals, subharmonic signals, and nonharmonically related signals upon the characteristics of the quenched-domain mode of Gunn-effect devices is evaluated for an X-band device at 1.5 times threshold voltage.     

Electron images of vidicon cathodes

Excessive patchiness of the emission from the oxide-coated cathodes used in cathode-ray tubes, camera tubes and traveling-wave tubes can have adverse effects on their performance or useful life. There is a simple technique for forming an electron image of a CRT cathode directly on the view screen. This technique, which has been known for more than 30 years, may be used to show patchiness when it exists, but it has not been possible in the past to image the cathode of a camera tube because of the lack of a built-in display mechanism (phosphor-coated view screen) and because of the peculiar geometry of the electron guns. A technique has now been devised for displaying the electron images of vidicon cathodes. This technique comprises) 1) priming the optical image-sensing surface with uniform light, 2) projecting a "pinhole snapshot" electron image of the cathode on the image-sensing surface with an unscanned beam and storing it there, and 3) reading out the stored image with the normal scanning beam and displaying it on a CRT monitor. Photographs of electron images of vidicon cathodes obtained in this manner are shown in this paper.     

Transient response of vidicon photoconductors

An expression for the rise and decay times of vidicon photocurrents as a function of incident illumination is derived for a certain class of vidicon photoconductors. The approach taken is semiempirical in that certain parameters in the derived expression are obtained directly from vidicon manufacturer's data sheets. Regults compare well with the manufacturer's published results.     

High-efficiency operation of a Gunn oscillator in the domain mode

An examination of the problem of obtaining high-efficiency operation of a Gunn oscillator is given in this paper. The results are based on an assumed form of I-V characteristic of the Gunn diode, the ideal voltage and current waveforms being found for high-efficiency operation. The theory for a square wave of current through and voltage across the diode is worked out in detail and shown to predict the experimental results well. It is shown that a voltage waveform consisting of only a fundamental and second harmonic component could give efficiencies in the 20-28 percent range, as much as a factor of 3 larger than for a simple sinusoid. This is a reasonable approximation to the ideal voltage waveform, which is a half sinusoid of voltage. In this paper the charge and discharge time of the domain is neglected. An estimate of these times is given in the Appendix, and it is shown that the efficiency theory should be relevant to operation with diodes for whichnL gg 10^{12}cm^-2. The theory may also describe certain types of "LSA mode" operation.     

A new silicon vidicon with a CdTe—Si target

A new type of a silicon vidicon target which utilizes blocking contacts between bulk semiconductor and a high resistive layer has been developed. The high resistive layer forms a blocking contact to the bulk and works also as a "resistive sea" layer, reducing complex fabrication processes. Structure of the target, tube characteristics, and video patterns are presented.     

Accumulation-punchthrough mode of operation of buried-channel MOSFET's

The current-voltage characteristics of a buried-channel MOSFET operated in a "punchthrough-accumulation" mode, when the neutral implanted channel is completely depleted due to punchthrough by substrate bias and an accumulation layer is induced by the gate, are demonstrated. It is shown that the value of one of the device model parameters, φMS, used under the above mode of operation corresponds to the gate and the substrate rather than to the gate and the channel.     

High-power operation mode of pulsed IMPATT diodes

Pulsed silicon double-drift IMPATT diodes that yield 42 W at 96 GHz are discussed. This is about twice the value reported previously. Owing to the considerable input powers (≈500 W), these diodes are mounted on diamond heat sinks. Because of the strong carrier injection, the field distribution in the diode is similar to that in a p-i-n diode. An attempt is made to explain the results using T. Misawa's (1966) p-i-n type theory. The large-signal; avalanche resonant frequency is close to the operation frequency. Conventional Read-type theory fails to explain these results because of the current densities employed in the experiments     

Differential mode of operation for bucket-brigade circuits

A differential circuit configuration is described that suppresses unwanted clock-frequency spectral energy at the output of a charge-transfer device. The differential mode of operation also eliminates the d.c. offset voltage that is characteristic of these devices. Experimental results are presented.     

Investigation of MOSFET operation in bipolar mode

The work is concerned with the properties of conventional MOSFET in bipolar mode of operation. It is shown that the base current can provide useful information about interface trap density at the Si–SiO₂ interface. The new device characteristics are found promising for use in low-voltage low-power logic circuits.     

试论智能变电站运维模式的研究

随着国民经济的发展以及信息化和智能化的推进,电力系统的智能化发展与普及已经成为时代发展的必然趋势.作为电力系统中的重要组成部分,变电站在应用和发展过程中受到了业界的广泛关注,本文意在研究智能变电站的运维模式.     

An economical color-television camera utilizing a silicon vidicon for electronic color separation

A new image device designed to electronically separate two kinds of color components from an optical image utilizing photoelectric properties of the surface of a silicon-vidicon target, and an economical color-TV camera using this device are proposed. This system requires neither special construction of a camera tube target to obtain index signals for color separation nor bias lighting. Crosstalk components present in the color signals from the color camera tube are corrected by circuitry. This color camera is about three times as high in sensitivity as that using an antimony trisulfide vidicon. It has many other features, including the capability of imaging a fixed object, without burn-in for a long time, as well as high reliability and long life.     

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.     

Enhanced dominant mode operation of a shielded multilayer coplanarwaveguide via substrate compensation

The cutoff frequency of the first higher-order even mode in a shielded multilayer coplanar waveguide (CPW) is studied using the spectral domain approach (SDA). The effective dielectric constant for the dominant odd and first higher-order even mode in a shielded multilayer CPW is computed and compared to other published numerical results. Dielectric constant and substrate height are varied with respect to even mode cutoff frequency and plotted for several CPW structures. Different combinations of internal substrates are shown to produce even mode cutoff frequency maximization for increased odd mode operation bandwidth     

The double discontinuous mode operation of a converter: a method for soft switching

This paper describes a way of ensuring soft switching in a converter without using additional components. This method is called double discontinuous mode (DDM). In particular, it permits any free wheeling diode to switch off at zero current, and for transistors to switch on at zero current and to switch off at zero voltage. The method illustrated here refers to a buck, but this concept may be applied to any type of converter, with or without transformer. Various mathematical models of this method are developed, and its characteristics and fields of application highlighted in this paper.