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Published in Philip A. Laplante, Comprehensive Dictionary of Electrical Engineering, 2018
categoric input categoric input a nonnumeric (symbolic) input, e.g., gender, color, which is usually fed to a network using one-out-of-N coding. catenation symbols strung together to form a larger sequence, as the characters in a word and the digits in a number. cathode the negative electrode of a device. Contrast with anode. cathode ray tube (CRT) a vacuum tube using cathode rays to generate a picture on a fluorescent screen. These cathode rays are in fact the electron beam deflected and modulated, which impinges on a phosphor screen to generate a picture according to a repetitive pattern refreshed at a frequency usually between 25 and 72 Hz. cathodoluminescent the property of luminescent crystals (phosphors) to emit visible light with bombarded electrons. catoptric an optical system made up of only reflective elements (mirrors). CATV See community-antenna television. depend upon future inputs applied to the circuit, and hence is a causal system. If a system is not causal, then it is noncausal. An ideal filter which will filter in real time all frequencies present in a signal f (t) requires knowledge of { f ( ) : > t}, and is an example of a noncausal system. causality a system H : Xe Xe , or equivalently, an operator that maps inputs from the extended space Xe into outputs from the same space where the output at time t is not a function of future inputs. This can be expressed using truncations as follows: A system H is causal if [H x(·)]T = [H x T (·)]T x Xe
Introduction to Phosphors, Rare Earths, Properties and Applications
Published in Vijay B. Pawade, Sanjay J. Dhoble, Phosphors for Energy Saving and Conversion Technology, 2018
Vijay B. Pawade, Sanjay J. Dhoble
A CRT consists of a vacuum tube containing an electron gun (cathode) and a phosphor-coated screen, as shown in Figure 2.14. The cathode is used as a filament, which on heating produces the electron beam. Electrons pass in a straight line through the anode and focusing coils, which are positioned on the upper and lower sides of the tube. The electrons are then focused and accelerated through the tube. Finally, they are incident on the fluorescent screen, showing a bright spot on the screen surface. Copper windings are wrapped around the tube and act as steering coils. These coils create magnetic fields inside the tube, and these magnetic fields steer the beam toward the screen. By varying the voltages in the coils, the electron beam can be positioned at any point on the screen. Color CRTs have three electron guns, one for each primary color. CRTs are used in oscilloscopes, television and computer monitors, and radar targets. Typical values of cathode to anode distance range are observed between 25 and 100 cm. CRTs are very bulky, and when bigger screens are required, the length of the tube must increase [124, 125]. For this application, the phosphor material should have specific characteristics [126, 127]. The application of phosphor powders for the purpose of screen coating is dependent on various interrelated parameters such as screening method, particle size distribution, and particle shape [128]. Some phosphors used in CRTs are as follows.
Cathode Ray Tube Displays
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
The cathode ray tube (CRT) is unequaled in its ability to produce dynamic, quality, high-information-content imagery at high resolution. Even more impressive is that it achieves this for a lower cost per pixel than any other comparable electronic display technology. For the instrument designer requiring a high-information-content display, it offers numerous advantages. As a raw image tube, it is commonly available as an off-the-shelf item with a broad infrastructure of vendors, integrators, support, and part suppliers. Interface standards are well established and as a complete system, ready to take a standard signal input, it is available worldwide in a variety of performance ranges. To meet different application requirements, it is available in diagonal sizes from 12 mm to over 1 m with resolution from thousands of pixels to over 5 million pixels per frame. Tube characteristics improve on a yearly basis, and prices continue to decrease. Although CRTs have been superseded by other display technologies, they are still used in many applications in laboratories, photography, transportation industry, and in military. They are used in medical applications for color comparisons [1,2].
The Changing Face of Public Broadcasting in India
Published in IETE Journal of Education, 2023
The CRT display has become obsolete now and has been overtaken by LCD displays. The ones put in the market, by the name of LED displays, are also LCD displays, except that the white light source in the back plane is an array of LED’s. The old LCD used a gas discharge tube for backplane illumination. The LCD display is x, y addressed type and individual pixels are defined by address lines. Color signals are steered to individual corresponding LCD elements. Thus the previous discussions, pertaining to signals created with CRT display in mind, have just lost relevance, in the context of LCD display. Address lines and color signal become important for the case of LCD / LED displays. The video interface of yesterday is deeply entrenched in the industry and a decoder is used in the LCD displays to handle analog composite video signals (CVSB). Display standards for TV have been given in Table 2.
The buildup factor calculations of concrete with different proportions of CRT based on a BP neural network by MCNP
Published in Journal of Nuclear Science and Technology, 2021
Han Gao, Xiang Li, Zhanpeng Li, Yidi Wang, Yunan Gao, Wei Tang, Long Chen, Congchong Yan, Yu Tu, Liang Sun
For decades, cathode ray tubes (CRTs) were the main display component of TVs and computers, but light emitting diode(LED) liquid crystal displays are now replacing CRTs. As a result, the number of discarded CRTs has rapidly increased. Because CRTs contain large quantities of lead oxides and other harmful heavy metal oxides, if the electronic waste containing CRTs is directly discarded without proper treatment, it can cause serious harm to the human body and the environment [1]. In the United States, it is estimated that approximately 200 million units of CRTs will require proper waste management from 2013 to 2033, as all CRT technology is expected to reach the end of life in 2033 [2]. At present, in most areas, discarded electronic products, including CRTs, are generally disposed of in landfills [1]. To eliminate the environmental risk of waste CRTs, it is necessary to find appropriate transformation and utilization methods.
Waste recycling of cathode ray tube glass through industrial production of transparent ceramic frits
Published in Journal of the Air & Waste Management Association, 2019
Owing to the high silicate content of CRTs, their recycling has great potential. On the other hand, they also contain toxic components such as lead, which limit their recyclability because of environmental concerns (Matamoros-Veloza et al. 2008). CRT monitors contain four different glass structures, namely, the front panel, the funnel, the frit, and the neck section. The front panel is made of colorful glass, which contains Ba and Sr. The funnel and neck contain glass with lead. The frit is a solder that melts at low temperatures (Andreola et al. 2005b). The usage ratio of front panel glass in standard CRTs is approximately 65%. The usage ratios of funnel glass and neck glass are approximately 35% and 5%, respectively (Méar et al. 2007). Funnel and neck glass constitute a risk in terms of toxicity because they contain high amounts of lead. For CRT monitors, the toxicity limit for front panel glass is lower than those for funnel and neck glass because the front panel only contains a small amount of lead and higher amounts of Ba and Sr than do the other CRT components (Chen, Zhang, and Zhu 2009).