difference between crt and lcd monitors made in china

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CRT stands for Cathode Ray Tube and LCD stands for Liquid Crystal Display area unit the kinds of display devices wherever CRT is employed as standard display devices whereas LCD is more modern technology. These area unit primarily differentiated supported the fabric they’re made from and dealing mechanism, however, each area unit alleged to perform identical perform of providing a visible variety of electronic media. Here, the crucial operational distinction is that the CRT integrates the 2 processes lightweight generation and lightweight modulation and it’s additionally managed by one set of elements. Conversely, the LCD isolates the 2 processes kind one another that’s lightweight generation and modulation.

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First, we will provide a brief technical overview of functional principles as they relate to visual stimulus presentation. Detailed descriptions and parameter measurements are already available from the existing literature; however, our intention here is to equip readers with limited technical expertise with the necessary knowledge to set up computer experiments with LCD monitors. Thus, we keep our explanations relatively short and simplified.

LCD monitors work differently: Each pixel consists of liquid crystal threads that can be twisted or arranged in parallel by an electrical current applied to them. This leads to a polarization effect that either allows or prevents light passing through. A white light source located behind this crystal array uniformly and constantly illuminates the array. To display a black pixel, the crystal threads are twisted by 90° such that no light will pass through. A white pixel is achieved by aligning the crystals such that maximum light is allowed to pass through, until a different, non-white color needs to be displayed (see the lower panel of Fig. 1 for an LCD pixel’s brightness over time). This is a static process, not a pulsed one as in CRTs.

In theory, the difference in presentation methods, namely a strobing versus a static image, should be of no consequence if the light energy that falls onto the retina remains the same over the time period of one single frame. As the Talbot-Plateau law states2 is equally well detectable as a light flash presented for 60 ms at 40 cd/m2. This suggests that temporal integration can be easily described by energy summation”. Thus, in principle, LCD and CRT monitors should be able to yield comparable results.

However, due to the differences in technology, the visual signals produced by the two display types have different shapes (i.e., a different light energy-over-time-curve; see Fig. 1). Moreover, default luminance as well as visual-signal response times (in addition to other parameters, see below) differ between most CRT and LCD monitors

Table 1 reports the parameters we considered in setting up the CRT and LCD monitors. Certainly, most of them are commonly considered when setting up a computer experiment; nevertheless we deemed it important to mention them here explicitly, as their neglect might have unintended consequences. We used a 17” Fujitsu Siemens Scenicview P796-2 CRT color monitor previously used in several published studies including studies with masked presentation conditions

We tested various monitor user settings, refresh rates, resolutions and luminance settings (see materials available at https://osf.io/g842s/) with regard to the emitted light energy–over-time-curve and therefore response characteristics (i.e., onset and offset of full screen and centrally presented stimuli). Measurements were conducted with a photodiode setup, using both an oscilloscope (model “Agilent MSOX 3012 A”) and a self-developed microcontroller setup as measurement devices. Stimuli were black and white squares.

Our measurements revealed several interesting characteristics: First, luminance of the LCD monitor at default setting (i.e., maximum brightness) exceeded the CRT luminance at a ratio of 3.25:1. However, comparable average luminance can be (and was) achieved by downregulating the LCD monitor (the older CRT technology emits less energy even at maximum settings, see Table 2), without participants perceiving it as unnaturally dark. If one plans to upgrade from CRT to LCD monitors in an experimental laboratory, we therefore recommend measuring the CRT monitors’ brightness levels and matching them in the new LCD monitors’ user setup, if comparability with the old setup is needed. This will minimize hardware-dependent variability, thus contributing to better replicability. Please note that a brightness adaption is not a necessary precondition when employing LCD monitors; researchers should simply be aware that the brightness level can have an influence onto the resulting effects, especially in time-critical experiments with short and/or masked presentation. Thus, we recommend the adaptation for time-critical experiments in which researchers orient on existing empirical evidence gathered with CRT monitors. Furthermore, gray-to-gray response times varied slightly depending on the employed brightness levels2), so we suggest that researchers can rely on this more efficient method as an approximation.

For the empirical comparison of human performance with CRT and LCD monitors, we relied on these results and set the monitor settings accordingly (see Method section below).

Participants were administered a masked number priming task and a subsequent forced-choice prime discrimination task using both a CRT and an LCD monitor. In this well-established paradigm

Of central interest was the question whether both monitors would yield comparable masked priming effects. Monitors were set according to the parameters described in the previous section (see also Method section below). In order to obtain conclusive evidence, we decided for sequential hypothesis testing using Bayes factorshttps://osf.io/g842s/.

Are LED monitors better than their LCD predecessors? How are the two technologies differ in terms of functionality and performance? All these questions will be answered by the LED vs. LCD comparison presented in here.

The age of CRT (cathode ray tube) displays is over and LCD displays are already being replaced with LED screens. Technology is evolving at an exponential pace, pushing existing technologies into obsolescence. Just when we thought LCD screens will be the default choice for some time to come, they were supplanted by LED monitors, with their superior power efficiency and rich picture quality.

Considering that we spend a major amount of our lifetime in front of screens these days and eyes are not a replaceable commodity, a discerning consumer must opt for technology that is soft on the eyes, while providing a rich visual experience.

There seems to be a lot of confusion about the differences between LED (Light Emitting Diode) and LCD (Liquid Crystal Display) monitors that need clarification. Here"s a succinct analysis of the similarities and differences between the two models.

LED and LCD monitors are based on the same basic technology for image display but differ in the kind of backlighting used. While LCD monitors use CCFL (cold cathode fluorescent lamps) for backlighting, the latter use light-emitting diodes. This is the prime difference between the two display technologies. So LED monitors are in actuality, a type of LCD monitors or an improvement over them.

Unlike CRT monitors that generate their own light through cathode ray incidence on fluorescent materials, LCD displays have to rely on external lighting, as their display is created through manipulation of light, passing through polarized liquid crystals. Backlighting affects picture quality substantially and light shed by LEDs offers superior picture quality compared to LCDs.

This is because LEDs offer much more gradation in intensity and a larger light wavelength spectrum, providing a truer color quality. These types of monitors offer a better dynamic contrast ratio as well. So if you compare LED and LCD monitors from a gaming perspective and for use in intensive graphic applications, LED monitors are surely better choices. They provide vivid and more lifelike colors, with better gradation.

LED monitors cure one of the basic problems with LCD TVs, which is the inability to display true black colors. They can produce true black hues, by switching off LEDs entirely, increasing the blackness quotient of the screen, and providing better contrast in the process.

LED monitors are a very recently introduced technology and they are preferred over LCD monitors because of the amazingly rich picture quality and viewing comfort. One more advantage that LED monitors to have over LCD ones is the power consumption factor. LED monitors require a lot less power to operate than cold cathode fluorescent lamps. This property can be attributed to the inherently low energy required by an LED to function. Their power consumption is as much as 40% lesser than conventional LCD monitors.

LED monitors are also a lot softer on the eyes than LCD monitors, making them popular choices for people who work for long hours on their desktop computers. They are also a lot more eco-friendly because mercury is not used in their production. LEDs last longer than cold cathode fluorescent lamps, with little reduction in their power output over time, which makes these monitors long-lasting.

To conclude this LCD vs. LED monitor comparison, let us compare the price ranges. One major factor that has been holding back LED technology from reaching the masses is the high price factor. The manufacturing of these devices is a bit costlier currently, compared to LCD displays which have raised their overall price. However, the cost gap is slowly lowering with time, as the demand for superior LED back-lit displays is on the rise all over the world. Even laptop computers and now smartphones come equipped with LED displays. While some of the best LCD monitors are available for a price of around $100, the best LED monitors fall in the $150 to $200+ range.

CRT and LCD are both display devices. CRT is an old technology whereas LCD is modern one. One major difference between CRT and LCD is in the technology used for image formation. The CRT display produces an image by using an electron beam, while LCD display produces an image on the screen using liquid crystal display.

CRT stands for Cathode Ray Tube. CRT displays produce an image on the screen by using a sharp beam of electrons that is highly focused to hit a phosphor screen present in front of the tube. The important components of a CRT are electron gun, focusing mechanism, and phosphor screen.

CRT was used in earlier TVs and computer monitors. CRT produces poor quality images on the screen and also consumes large electricity. The lifespan of CRT displays is very short. Because of all reasons, CRTs are being replaced by other display technologies these days.

LCD stands for Liquid Crystal Display. In LCD, liquid crystals are used to produce images on the screen. LCD displays are thin and more energy efficient, thus they are used in several small sized devices like mobiles, laptops, TVs, desktop computer monitors, calculators, etc.

In LCDs, light is obtained from external sources, and then it is converted into a definite graphics pattern using optical effects. LCDs have several advantages over CRT such as less power consumption, faster response, smaller size, low cost, etc.

Both CRT and LCD have their own advantages and disadvantages. However, these days, CRTs have almost become extinct. No one seems to be using them anymore. LCDs and other display technologies have replaced them because the new devices are highly efficient in terms of cost, power, and performance.

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Direct exposure of bare skin to strong light after PDT can cause severe skin phototoxicity although the superficial light irradiation has a limited tissue penetration depth. Therefore, the patient is advised to avoid direct light exposure to the skin after the administration of the photosensitizer. The length of light avoidance after PDT depends on the retention time of photosensitizer in the normal skin, which can be affected by the nature and dose of photosensitizer and its administration route, and body site [

Incidences of post-PDT skin phototoxicity are often associated with patients who fail to heed the advice of strict light avoidance. Rather than indoor light, sunlight exposure shortly after receiving an exogenous photosensitizer or prodrug presents a major risk factor for skin phototoxicity. Although rare, exposure to CRT or LCD monitor emissions after PDT can also cause cutaneous phototoxicity on bare skin [

Color CRT monitors use a phosphor-coated screen. Phosphors are arranged in strips and emit visible light when exposed to an electron beam generated within the CRT. Three beams are used in CRT monitors to excite red, green, and blue color in combinations needed to create the various hues that form the picture. CRT monitors are gradually being replaced by LCD flat panel monitors in households and offices. The light emitting mechanism of LCD monitors is different than that of CRTs. LCD displays use two basic techniques for producing color: passive matrix or thin film transistor. Basically, LCD monitors utilize two sheets of polarizing material with a segmented liquid crystal solution between them. An electric current passes through the liquid causing the crystals to align so that the light emission of individual pixels can be controlled. LCD monitors are typically backlit by a white light fluorescent (fluorescent-backlit) or LED light (LED-backlit) source since the liquid crystals generate no light of their own.

This study examined the light emission profiles of common CRT, LCD, and LED monitors utilizing simulated movie and video game streams. The range of optical irradiance generated from the movie stream was broader than that from the game stream (see Fig. 2). The 50% points of the cumulative ratio for the game were slightly higher than that of the movie (see Fig. 3). Using a representative figure of 1 μW/cm2 as an example, it can be estimated that 10 min exposure to a monitor at a distance of 18 in. can deliver a total fluence of 0.6 mJ/cm2, i.e., 60 μJ/cm2/min to the skin surface. This estimated fluence rate is considerably lower than that of sunlight or PDT light, which are typically at 101–102 mW/cm2 range. The moderate monitor settings (e.g., the total emission intensity of 6:5 μW/cm2 at the measurement point), randomly selected video streams, and longer sensor-to-monitor distance (e.g., 18 in.) might cause an underestimate of the fluence rate. It should be noted that the actual light emission profiles depend on several factors, including the size and configuration of monitor screen, program being played back on the screen, and its duration. The light fluence received by the skin is also affected by the screen-to-face distance and their alignment. Furthermore, the light fluence inside the skin of a multilayered geometry can be significantly affected not only by light source but also by tissue optical properties [

For 10 min of the movie or game the integrated fluence from the CRT’s visible emission (467.5–800 nm) measured by the spectrometer at the same face position (i.e., 18 in. from the monitor) was approximately 1 mJ/cm2. This value was higher than that estimated from the optical irradiance (0.6 mJ/cm2) measured by the Si photodiode. It needs to be pointed out that the Si photodiode used in this study is wavelength dependent. As the wavelength was set up at 635 nm, it might underestimate the actual total optical irradiance. Interestingly, under the same condition, the integrated fluence from the LCD or LED was 40% or 80% higher than that of the CRT. The active diagonal screen size of the CRT, LCD, and LED was 16, 15, and 17.2 in., respectively. Under the white screen mode, the relative fluence of visible emission from the LCD or LED was 40% or 60% higher than that of the CRT when the total emission intensity was set up at the same level (see Fig. 1). Although the difference in the screen size might contribute to some variation, this finding suggests that the common assumption that LCD and LED monitors might be safer than older CRT monitors is incorrect in terms of potential risk of skin phototoxicity.

In some cases, the back of the hands can be exposed to monitor light while working on the keyboard. A recent report indicated that mild phototoxicity could occur on the back of both hands after PDT when the hands were exposed to an LCD monitor for a few hours [

It has been a concern that overexposure to UV and visible radiation in the presence and absence of photosensitizer might be also detrimental to the eye and subsequently to vision [

In summary, our results suggest that the optical and spectral profiles of emissions from color monitors are clinically relevant. Therefore, prolonged exposure to monitor emissions at a close distance might pose as a potential risk to the face, eyes, and hands. Future guidelines on post-PDT care and patient warnings should include the avoidance of overexposure to common light sources, such as computers, video games, and TV monitors after receiving a topical and systemic administration of a photosensitizer. This should be emphasized to certain high-risk patient populations, e.g., teenagers who may play video games for extended periods of time and people who receive repeated topical application of a photosensitizer or prodrug at a short period of time or work long hours in front of a large and bright monitor screen. The same caution is also applicable to patients who take drugs known to cause photoallergic, photosensitive, and phototoxic reactions.

Since the production of cathode ray tubes has essentially halted due to the cost and environmental concerns, CRT-based monitors are considered an outdated technology. All laptops and most desktop computer systems sold today come with LCD monitors. However, there are a few reasons why you might still prefer CRT over LCD displays.

While CRT monitors provide better color clarity and depth, the fact that manufacturers rarely make them anymore makes CRTs an unwise choice. LCD monitors are the current standard with several options. LCD monitors are smaller in size and easier to handle. Plus, you can buy LCD monitors in a variety of sizes, so customizing your desktop without all the clutter is easy.

The primary advantage that CRT monitors hold over LCDs is color rendering. The contrast ratios and depths of colors displayed on CRT monitors are better than what an LCD can render. For this reason, some graphic designers use expensive and large CRT monitors for their work. On the downside, the color quality degrades over time as the phosphors in the tube break down.

Another advantage that CRT monitors hold over LCD screens is the ability to easily scale to various resolutions. By adjusting the electron beam in the tube, the screen can be adjusted downward to lower resolutions while keeping the picture clarity intact. This capability is known as multisync.

The biggest disadvantage of CRT monitors is the size and weight of the tubes. An equivalently sized LCD monitor can be 80% smaller in total mass. The larger the screen, the bigger the size difference. CRT monitors also consume more energy and generate more heat than LCD monitors.

For the most vibrant and rich colors, CRTs are hard to beat if you have the desk space and don"t mind the excessive weight. However, with CRTs becoming a thing of the past, you may have to revisit the LCD monitor.

The biggest advantage of LCD monitors is the size and weight. LCD screens also tend to produce less eye fatigue. The constant light barrage and scan lines of a CRT tube can cause strain on heavy computer users. The lower intensity of the LCD monitors coupled with the constant screen display of pixels being on or off is easier on the eyes. That said, some people have issues with the fluorescent backlights used in some LCD displays.

The most notable disadvantage to LCD screens is the fixed resolution. An LCD screen can only display the number of pixels in its matrix. Therefore, it can display a lower resolution in one of two ways: using only a fraction of the total pixels on the display, or through extrapolation. Extrapolation blends multiple pixels together to simulate a single smaller pixel, which often leads to a blurry or fuzzy picture.

For those who are on a computer for hours, an LCD can be an enemy. With the tendency to cause eye fatigue, computer users must be aware of how long they stare at an LCD monitor. While LCD technology is continually improving, using techniques to limit the amount of time you look at a screen alleviates some of that fatigue.

Significant improvements have been made to LCD monitors over the years. Still, CRT monitors provide greater color clarity, faster response times, and wider flexibility for video playback in various resolutions. Nonetheless, LCDs will remain the standard since these monitors are easier to manufacture and transport. Most users find LCD displays to be perfectly suitable, so CRT monitors are only necessary for those interested in digital art and graphic design.

CRTs are analog devices controlled by the varying voltages in the signal. There are also two controls for each of the three "beams" coming off the electron gun: bias and gain. When the three bias controls and gain controls are lumped together, you have contrast and brightness. All of these together control the floor and ceiling of the amplification (black and white luminance) as well as how quickly the luminance of the display increases from black to white. These are the controls most users know.

LCDs are digital devices and are a completely different animal. When run digitally, there is no bias or gain and in some instances...no contrast adjustment. The only variation is the intensity of the backlight. This is how LCDs connected to a computer through a DVI or ADC cable will operate. Unfortunately, digital interfaces for displays did not exist when LCDs were first introduced, so manufacturers tried to graft on analog controls since an analog signal was being used. This has caused mixed results. In most cases, setting brightness and/or contrast too high on an LCD with an analog connection will introduce clipping of the lighter tones.

Our goal is to achieve the highest contrast ratio and luminance without introducing clipping. We are measuring the luminance of a white patch and a very light gray patch and checking to see if there is an appropriate difference between them. We have found that some displays (usually laptops) will not produce a large enough luminance difference between the two patches regardless of the contrast setting. You can do this test visually. The alternating patches will be displayed continuously. If you can see them change with contrast all the way up, you can proceed. If not, turn the contrast down until you can see the difference and then proceed.

LCDs respond rather slowly to contrast and brightness adjustments and may take some time to stabilize. Since they change over time, this can cause the luminance of two sequential measurements to be greater or smaller, thus causing the indicator to move. That"s why we recommend waiting for the indicator to stabilize. When the indicator stabilizes, the display probably has as well.

The temporal and spatial luminance characteristics of a CRT monitor and two LCD monitors were tested. The CRT monitor (P1230, Dell Inc. TX, USA, referred to as “CRT”) had maintained an excellent working condition after 10 years of use. The first LCD monitor (ASUS PG278Q) was tested in two different modes: once in the ULMB mode, which was our candidate and is referred to here as “LCD1-ULMB,” and once in Overdrive (OD) mode, which we refer to as “LCD1-OD.” The second monitor was an ASUS VG278 tested in the standard mode (LCD2). All the tested monitors were driven by an NVIDIA GeForce GTX 960 graphics card.

The monitors’ configurations and basic luminance characteristics are shown in Table 1. The contrast was set to 50%, 80%, and 100% for LCD1, LCD2, and CRT, respectively. The luminance was set to 90% for LCD1 and CRT, and to 100% for LCD2. The resolution of the CRT was set to 1,024 × 768 pixels, and the LCDs were set to their native resolutions, which were 2,560 × 1,440 for LCD1 and 1,920 × 1,080 for LCD2. A refresh rate of 120 Hz was used for all monitors. The user-mode and the default-mode color temperatures were used for the LCDs and CRT, respectively. These settings were kept constant throughout the test.

Luminance was measured in two ways. First, a photodiode (BPW21R, Vishay Intertechnology, Inc. ShangHai, China) with a switch time below 1 μs was placed in the centers of different areas of the monitor to measure their temporal and spatial characteristics. Voltages, proportional to luminance changes, were amplified and recorded by an electrophysiology (EEG) recording system (Synamps II, Compumedics NeuroScan, Charlotte, USA) at a sampling rate of 10 kHz and were used to characterize the luminance properties of each monitor. The second method was to use a ColorCal MKII photometer (Cambridge Research Systems Ltd., Cambridge, UK) to measure the dependence of luminance on pixel location and viewing angle.

All measurements were taken in a dark room after the monitors had been turned on for at least 60 min, to minimize variation due to warming up (Klein, Zlatkova, Lauritzen, & Pierscionek, 2013). The study was approved by the Academic Committee of the College of Education, Soochow University. All of the Matlab code to analyze the data is available at https://github.com/yangzhangpsy/monitorTestForPsy.

To measure the spatial homogeneity of luminance, the whole display of each monitor was divided evenly into nine rectangular areas (appearing as a 3 × 3 grid). The centers of the nine areas were measured one by one in a random order. Test images were generated and displayed over these nine areas using Matlab (2011b; MathWorks Inc., Natick, USA) with Psychtoolbox (3.0.14; Pelli, 1997b).

Three series of tests were carried out using two different types of images. The first series tested the luminance dependence on pixel location and time (Pelli, 1997a). The test was based on presentation of a solid white ellipse fitting the inside of each rectangular area of the display, and measurements were made using the photodiode placed in the center of the ellipse over each area. Each location was tested for 50 trials, each of which consisted of a black display (100 ms) and an image (33.3 ms). A trigger was sent to the EEG amplifiers by the photodiode via a parallel port when the image appeared on the screen.

The luminance dependence on viewing angle was measured in the third test series for the CRT and LCD1-ULMB (the candidate monitor). The luminance at the center of the screen was measured with the photometer 28.5 cm away from the screen center at seven viewing angles (– 45°, – 30°, – 15°, 0°, 15°, 30°, and 45°) along the horizontal meridian. The luminance at each viewing angle was measured five times and then normalized to the maximum luminance of each monitor measured at 0°.

To understand the spatial and temporal characteristics of the monitors, two parameters—initial latency and relative maximum luminance of the first frame (RML1st)—were calculated from luminance values measured with the photodiode for each trial at each location. Because the luminance was recorded with the EEG system at a digitizing rate of 10 kHz, the temporal resolution was 0.1 ms. To calculate the initial latency, the stimulus onset time was detected as the time point at which the luminance first reached or exceeded 40% of the maximum luminance (with the restriction that the eight consecutive bins just before the onset time bin should be less than 44% of the maximum potential). The initial latency was then calculated as the interval between the stimulus trigger and stimulus onset.

RML1st was defined as the percentage of the maximum luminance of the first frame relative to the maximum luminance over the second and third frames. The maximum luminance was defined differently for different monitors, since the images were displayed continuously for LCD1-OD and LCD2 but displayed in a flash style for CRT and LCD1-ULMB. For the continuously displaying monitors (LCD1-OD and LCD2), the maximum luminance for the first frame was defined as the mean luminance over the first 8.2 ms (corresponding to the duration of a single frame at a 120-Hz refresh rate), whereas the maximum luminance over the next two frames was defined as the mean luminance from 8.3 to 24.9 ms. For the CRT, the maximum luminance was defined as the mean luminance around peaks (0.1 to 0.6 ms, 8.4 to 8.9 ms, and 16.8 to 17.3 for the first, second, and third frames, respectively). For LCD1-ULMB, the maximum luminance was defined as the mean luminance around plateaus (0 to 1.6 ms, 8.3 to 9.9 ms, and 16.7 to 18.3 ms for the first three frames, respectively).

A cathode-ray tube (CRT) is a vacuum tube containing one or more electron guns, which emit electron beams that are manipulated to display images on a phosphorescent screen.waveforms (oscilloscope), pictures (television set, computer monitor), radar targets, or other phenomena. A CRT on a television set is commonly called a picture tube. CRTs have also been used as memory devices, in which case the screen is not intended to be visible to an observer. The term

In CRT television sets and computer monitors, the entire front area of the tube is scanned repeatedly and systematically in a fixed pattern called a raster. In color devices, an image is produced by controlling the intensity of each of three electron beams, one for each additive primary color (red, green, and blue) with a video signal as a reference.magnetic deflection, using a deflection yoke. Electrostatic deflection is commonly used in oscilloscopes.

A CRT is a glass envelope which is deep (i.e., long from front screen face to rear end), heavy, and fragile. The interior is evacuated to 0.01 pascals (1×10−7 atm)×10−12 atm) or less,implosion that can hurl glass at great velocity. The face is typically made of thick lead glass or special barium-strontium glass to be shatter-resistant and to block most X-ray emissions. CRTs make up most of the weight of CRT TVs and computer monitors.

Since the mid-late 2000"s, CRTs have been superseded by flat-panel display technologies such as LCD, plasma display, and OLED displays which are cheaper to manufacture and run, as well as significantly lighter and less bulky. Flat-panel displays can also be made in very large sizes whereas 40 in (100 cm) to 45 in (110 cm)

Cathode rays were discovered by Julius Plücker and Johann Wilhelm Hittorf.cathode (negative electrode) which could cast shadows on the glowing wall of the tube, indicating the rays were traveling in straight lines. In 1890, Arthur Schuster demonstrated cathode rays could be deflected by electric fields, and William Crookes showed they could be deflected by magnetic fields. In 1897, J. J. Thomson succeeded in measuring the charge-mass-ratio of cathode rays, showing that they consisted of negatively charged particles smaller than atoms, the first "subatomic particles", which had already been named George Johnstone Stoney in 1891. The earliest version of the CRT was known as the "Braun tube", invented by the German physicist Ferdinand Braun in 1897.cold-cathode diode, a modification of the Crookes tube with a phosphor-coated screen. Braun was the first to conceive the use of a CRT as a display device.

The first cathode-ray tube to use a hot cathode was developed by John Bertrand Johnson (who gave his name to the term Johnson noise) and Harry Weiner Weinhart of Western Electric, and became a commercial product in 1922.

In 1926, Kenjiro Takayanagi demonstrated a CRT television receiver with a mechanical video camera that received images with a 40-line resolution.Philo Farnsworth created a television prototype.Vladimir K. Zworykin.: 84 RCA was granted a trademark for the term (for its cathode-ray tube) in 1932; it voluntarily released the term to the public domain in 1950.

In the 1930s, Allen B. DuMont made the first CRTs to last 1,000 hours of use, which was one of the factors that led to the widespread adoption of television.

From 1949 to the early 1960s, there was a shift from circular CRTs to rectangular CRTs, although the first rectangular CRTs were made in 1938 by Telefunken.

1968 marks the release of Sony Trinitron brand with the model KV-1310, which was based on Aperture Grille technology. It was acclaimed to have improved the output brightness. The Trinitron screen was identical with its upright cylindrical shape due to its unique triple cathode single gun construction.

In 1987, flat-screen CRTs were developed by Zenith for computer monitors, reducing reflections and helping increase image contrast and brightness.float glass.

In the mid-2000s, Canon and Sony presented the surface-conduction electron-emitter display and field-emission displays, respectively. They both were flat-panel displays that had one (SED) or several (FED) electron emitters per subpixel in place of electron guns. The electron emitters were placed on a sheet of glass and the electrons were accelerated to a nearby sheet of glass with phosphors using an anode voltage. The electrons were not focused, making each subpixel essentially a flood beam CRT. They were never put into mass production as LCD technology was significantly cheaper, eliminating the market for such displays.

Beginning in the late 90s to the early 2000s, CRTs began to be replaced with LCDs, starting first with computer monitors smaller than 15 inches in size,Hitachi in 2001,Flat-panel displays dropped in price and started significantly displacing cathode-ray tubes in the 2000s. LCD monitor sales began exceeding those of CRTs in 2003–2004

Despite being a mainstay of display technology for decades, CRT-based computer monitors and televisions are now virtually a dead technology. Demand for CRT screens dropped in the late 2000s.

Some industries still use CRTs because it is either too much effort, downtime, and/or cost to replace them, or there is no substitute available; a notable example is the airline industry. Planes such as the Boeing 747-400 and the Airbus A320 used CRT instruments in their glass cockpits instead of mechanical instruments.Lufthansa still use CRT technology, which also uses floppy disks for navigation updates.

A popular consumer usage of CRTs is for retrogaming. Some games are impossible to play without CRT display hardware, and some games play better. Reasons for this include:

The size of the screen of a CRT is measured in two ways: the size of the screen or the face diagonal, and the viewable image size/area or viewable screen diagonal, which is the part of the screen with phosphor. The size of the screen is the viewable image size plus its black edges which are not coated with phosphor.

Small CRTs below 3 inches were made for handheld televisions such as the MTV-1 and viewfinders in camcorders. In these, there may be no black edges, that are however truly flat.

Most of the weight of a CRT comes from the thick glass screen, which comprises 65% of the total weight of a CRT. The funnel and neck glass comprise the remaining 30% and 5% respectively. The glass in the funnel is thinner than on the screen.

The outer conductive coating is connected to ground while the inner conductive coating is connected using the anode button/cap through a series of capacitors and diodes (a Cockcroft–Walton generator) to the high voltage flyback transformer; the inner coating is the anode of the CRT,voltage multiplier for the current delivered by the flyback.

The anode is used to accelerate the electrons towards the screen and also collects the secondary electrons that are emitted by the phosphor particles in the vacuum of the CRT.

The anode cap connection in modern CRTs must be able to handle up to 55–60 kV depending on the size and brightness of the CRT. Higher voltages allow for larger CRTs, higher image brightness, or a tradeoff between the two.corona discharge.

The anode button must be specially shaped to establish a hermetic seal between the button and funnel. X-rays may leak through the anode button, although that may not be the case in newer CRTs starting from the late 1970s to early 1980s, thanks to a new button and clip design.

The flyback transformer is also known as an IHVT (Integrated High Voltage Transformer) if it includes a voltage multiplier. The flyback uses a ceramic or powdered iron core to enable efficient operation at high frequencies. The flyback contains one primary and many secondary windings that provide several different voltages. The main secondary winding supplies the voltage multiplier with voltage pulses to ultimately supply the CRT with the high anode voltage it uses, while the remaining windings supply the CRT"s filament voltage, keying pulses, focus voltage and voltages derived from the scan raster. When the transformer is turned off, the flyback"s magnetic field quickly collapses which induces high voltage in its windings. The speed at which the magnetic field collapses determines the voltage that is induced, so the voltage increases alongside its speed. A capacitor (Retrace Timing Capacitor) or series of capacitors (to provide redundancy) is used to slow the collapse of the magnetic field.

The design of the high voltage power supply in a product using a CRT has an influence in the amount of x-rays emitted by the CRT. The amount of emitted x-rays increases with both higher voltages and currents. If the product such as a TV set uses an unregulated high voltage power supply, meaning that anode and focus voltage go down with increasing electron current when displaying a bright image, the amount of emitted x-rays is as its highest when the CRT is displaying a moderately bright images, since when displaying dark or bright images, the higher anode voltage counteracts the lower electron beam current and vice versa respectively. The high voltage regulator and rectifier vacuum tubes in some old CRT TV sets may also emit x-rays.

The electron gun emits the electrons that ultimately hit the phosphors on the screen of the CRT. The electron gun contains a heater, which heats a cathode, which generates electrons that, using grids, are focused and ultimately accelerated into the screen of the CRT. The acceleration occurs in conjunction with the inner aluminum or aquadag coating of the CRT. The electron gun is positioned so that it aims at the center of the screen.

It has a hot cathode that is heated by a tungsten filament heating element; the heater may draw 0.5 to 2 A of current depending on the CRT. The voltage applied to the heater can affect the life of the CRT.

There are several shortcircuits that can occur in a CRT electron gun. One is a heater-to-cathode short, that causes the cathode to permanently emit electrons which may cause an image with a bright red, green or blue tint with retrace lines, depending on the cathode (s) affected. Alternatively, the cathode may short to the control grid, possibly causing similar effects, or, the control grid and screen grid (G2)sputtering.

Since it is a hot cathode, it is prone to cathode poisoning, which is the formation of a positive ion layer that prevents the cathode from emitting electrons, reducing image brightness significantly or completely and causing focus and intensity to be affected by the frequency of the video signal preventing detailed images from being displayed by the CRT. The positive ions come from leftover air molecules inside the CRT or from the cathode itself

However, electrostatic focusing cannot be accomplished near the final anode of the CRT due to its high voltage in the dozens of Kilovolts, so a high voltage (≈600

There is a voltage called cutoff voltage which is the voltage that creates black on the screen since it causes the image on the screen created by the electron beam to disappear, the voltage is applied to G1. In a color CRT with three guns, the guns have different cutoff voltages. Many CRTs share grid G1 and G2 across all three guns, increasing image brightness and simplifying adjustment since on such CRTs there is a single cutoff voltage for all three guns (since G1 is shared across all guns).

During retracing of the electron beam, the preamplifier that feeds the video amplifier is disabled and the video amplifier is biased to a voltage higher than the cutoff voltage to prevent retrace lines from showing, or G1 can have a large negative voltage applied to it to prevent electrons from getting out of the cathode.Vertical blanking interval and Horizontal blanking interval.) Incorrect biasing can lead to visible retrace lines on one or more colors, creating retrace lines that are tinted or white (for example, tinted red if the red color is affected, tinted magenta if the red and blue colors are affected, and white if all colors are affected).

The electron beam may be affected by the earth"s magnetic field, causing it to normally enter the focusing lens off-center; this can be corrected using astigmation controls. Astigmation controls are both magnetic and electronic (dynamic); magnetic does most of the work while electronic is used for fine adjustments.

Some electron guns have a quadrupole lens with dynamic focus to alter the shape and adjust the focus of the electron beam, varying the focus voltage depending on the position of the electron beam to maintain image sharpness across the entire screen, specially at the corners.

The electron guns in color CRTs are driven by a video amplifier which takes a signal per color channel and amplifies it to 40-170v per channel, to be fed into the electron gun"s cathodes;

CRTs have a pronounced triode characteristic, which results in significant gamma (a nonlinear relationship in an electron gun between applied video voltage and beam intensity).

There are two types of deflection: magnetic and electrostatic. Magnetic is usually used in TVs and monitors as it allows for higher deflection angles (and hence shallower CRTs) and deflection power (which allows for higher electron beam current and hence brighter images)

Those that use magnetic deflection may use a yoke that has two pairs of deflection coils; one pair for vertical, and another for horizontal deflection.

The deflection coils are driven by sawtooth signalsHorizontal scan rate) of 15 to 240 kHz depending on the refresh rate of the CRT and the number of horizontal lines to be drawn (the vertical resolution of the CRT). The higher frequency makes it more susceptible to interference, so an automatic frequency control (AFC) circuit may be used to lock the phase of the horizontal deflection signal to that of a sync signal, to prevent the image from becoming distorted diagonally. The vertical frequency varies according to the refresh rate of the CRT. So a CRT with a 60 Hz refresh rate has a vertical deflection circuit running at 60 Hz. The horizontal and vertical deflection signals may be generated using two circuits that work differently; the horizontal deflection signal may be generated using a voltage controlled oscillator (VCO) while the vertical signal may be generated using a triggered relaxation oscillator. In many TVs, the frequencies at which the deflection coils run is in part determined by the inductance value of the coils.

Mostly used in oscilloscopes. Deflection is carried out by applying a voltage across two pairs of plates, one for horizontal, and the other for vertical deflection. The electron beam is steered by varying the voltage difference across plates in a pair; For example, applying a voltage to the upper plate of the vertical deflection pair, while keeping the voltage in the bottom plate at 0 volts, will cause the electron beam to be deflected towards the upper part of the screen; increasing the voltage in the upper plate while keeping the bottom plate at 0 will cause the electron beam to be deflected to a higher point in the screen (will cause the beam to be deflected at a higher deflection angle). The same applies with the horizontal deflection plates. Increasing the length and proximity between plates in a pair can also increase the deflection angle.

Burn-in is when images are physically "burned" into the screen of the CRT; this occurs due to degradation of the phosphors due to prolonged electron bombardment of the phosphors, and happens when a fixed image or logo is left for too long on the screen, causing it to appear as a "ghost" image or, in severe cases, also when the CRT is off. To counter this, screensavers were used in computers to minimize burn-in.

CRTs are evacuated or exhausted (a vacuum is formed) inside an oven at approx. 375–475 °C, in a process called baking or bake-out.turbomolecular pump or a diffusion pump.getter is then fired using an RF (induction) coil. The getter is usually in the funnel or in the neck of the CRT.

CRTs used to be rebuilt; repaired or refurbished. The rebuilding process included the disassembly of the CRT, the disassembly and repair or replacement of the electron gun(s), the removal and redeposition of phosphors and aquadag, etc. Rebuilding was popular until the 1960s because CRTs were expensive and wore out quickly, making repair worth it.

Also known as rejuvenation, the goal is to temporarily restore the brightness of a worn CRT. This is often done by carefully increasing the voltage on the cathode heater and the current and voltage on the control grids of the electron gun manually

Phosphors in CRTs emit secondary electrons due to them being inside the vacuum of the CRT. The secondary electrons are collected by the anode of the CRT.

SMPTE-C phosphors have properties defined by the SMPTE-C standard, which defines a color space of the same name. The standard prioritizes accurate color reproduction, which was made difficult by the different phosphors and color spaces used in the NTSC and PAL color systems. PAL TV sets have subjectively better color reproduction due to the use of saturated green phosphors, which have relatively long decay times that are tolerated in PAL since there is more time in PAL for phosphors to decay, due to its lower framerate. SMPTE-C phosphors were used in professional video monitors.

The phosphor coating on monochrome and color CRTs may have an aluminum coating on its rear side used to reflect light forward, provide protection against ions to prevent ion burn by negative ions on the phosphor, manage heat generated by electrons colliding against the phosphor,

Various phosphors are available depending upon the needs of the measurement or display application. The brightness, color, and persistence of the illumination depends upon the type of phosphor used on the CRT screen. Phosphors are available with persistences ranging from less than one microsecond to several seconds.

Variations in anode voltage can lead to variations in brightness in parts or all of the image, in addition to blooming, shrinkage or the image getting zoomed in or out. Lower voltages lead to blooming and zooming in, while higher voltages do the opposite.

Doming is a phenomenon found on some CRT televisions in which parts of the shadow mask become heated. In televisions that exhibit this behavior, it tends to occur in high-contrast scenes in which there is a largely dark scene with one or more localized bright spots. As the electron beam hits the shadow mask in these areas it heats unevenly. The shadow mask warps due to the heat differences, which causes the electron gun to hit the wrong colored phosphors and incorrect colors to be displayed in the affected area.

Bimetal springs may be used in CRTs used in TVs to compensate for warping that occurs as the electron beam heats the shadow mask, causing thermal expansion.

Size is limited by anode voltage, as it would require a higher dielectric strength to prevent arcing (corona discharge) and the electrical losses and ozone generation it causes, without sacrificing image brightness. The weight of the CRT, which originates from the thick glass needed to safely sustain a vacuum, imposes a practical limit on the size of a CRT.

At high deflection angles, resolutions and refresh rates (since higher resolutions and refresh rates require significantly higher frequencies to be applied to the horizontal deflection coils), the deflection yoke starts to produce large amounts of heat, due to the need to move the electron beam at a higher angle, which in turn requires exponentially larger amounts of power. As an example, to increase the deflection angle from 90 to 120°, power consumption of the yoke must also go up from 40 watts to 80 watts, and to increase it further from 120 to 150°, deflection power must again go up from 80 watts to 160 watts. This normally makes CRTs that go beyond certain deflection angles, resolutions and refresh rates impractical, since the coils would generate too much heat due to resistance caused by the skin effect, surface and eddy current losses, and/or possibly causing the glass underneath the coil to become conductive (as the electrical conductivity of glass decreases with increasing temperature). Some deflection yokes are designed to dissipate the heat that comes from their operation.

On CRTs, refresh rate depends on resolution, both of which are ultimately limited by the maximum horizontal scanning frequency of the CRT. Motion blur also depends on the decay time of the phosphors. Phosphors that decay too slowly for a given refresh rate may cause smearing or motion blur on the image. In practice, CRTs are limited to a refresh rate of 160 Hz.quantum dot LCDs (QLEDs) are available in high refresh rates (up to 144 Hz)

CRT monitors can still outperform LCD and OLED monitors in input lag, as there is no signal processing between the CRT and the display connector of the monitor, since CRT monitors often use VGA which provides an analog signal that can be fed to a CRT directly. Video cards designed for use with CRTs may have a RAMDAC to generate the analog signals needed by the CRT.multisyncing.

Picture tube CRTs have overscan, meaning the actual edges of the image are not shown; this is deliberate to allow for adjustment variations between CRT TVs, preventing the ragged edges (due to blooming) of the image from being shown on screen. The shadow mask may have grooves that reflect away the electrons that do not hit the screen due to overscan.

If the CRT is a black and white (B&W or monochrome) CRT, there is a single electron gun in the neck and the funnel is coated on the inside with aluminum that has been applied by evaporation; the aluminum is evaporated in a vacuum and allowed to condense on the inside of the CRT.ion traps, necessary to prevent ion burn on the phosphor, while also reflecting light generated by the phosphor towards the screen, managing heat and absorbing electrons providing a return path for them; previously funnels were coated on the inside with aquadag, used because it can be applied like paint;

The screen, funnel and neck are fused together into a single envelope, possibly using lead enamel seals, a hole is made in the funnel onto which the anode cap is installed and the phosphor, aquadag and aluminum are applied afterwards.

The interior aquadag or aluminum coating was the anode and served to accelerate the electrons towards the screen, collect them after hitting the screen while serving as a capacitor together with the outer aquadag coating. The screen has a single uniform phosphor coating and no shadow mask, technically having no resolution limit.

Monochrome CRTs may use ring magnets to adjust the centering of the electron beam and magnets around the deflection yoke to adjust the geometry of the image.

Color CRTs use three different phosphors which emit red, green, and blue light respectively. They are packed together in stripes (as in aperture grille designs) or clusters called "triads" (as in shadow mask CRTs).

Color CRTs have three electron guns, one for each primary color, (red, green and blue) arranged either in a straight line (in-line) or in an equilateral triangular configuration (the guns are usually constructed as a single unit).

Trinitron CRTs were different from other color CRTs in that they had a single electron gun with three cathodes, an aperture grille which lets more electrons through, increasing image brightness (since the aperture grille does not block as many electrons), and a vertically cylindrical screen, rather than a curved screen.

The three electron guns are in the neck (except for Trinitrons) and the red, green and blue phosphors on the screen may be separated by a black grid or matrix (called black stripe by Toshiba).

Shadow masks were replaced in TVs by slot masks in the 1970s, since slot masks let more electrons through, increasing image brightness. Shadow masks may be connected electrically to the anode of the CRT.Cromaclear; Trinitron and Diamondtron use aperture grilles while Cromaclear uses a slot mask. Some shadow mask CRTs have color phosphors that are smaller in diameter than the electron beams used to light them,

Several methods were used to create the black matrix. One method coated the screen in photoresist such as dichromate-sensitized polyvinyl alcohol photoresist which was then dried and exposed; the unexposed areas were removed and the entire screen was coated in colloidal graphite to create a carbon film, and then hydrogen peroxide was used to remove the remaining photoresist alongside the carbon that was on top of it, creating holes that in turn created the black matrix. The photoresist had to be of the correct thickness to ensure sufficient adhesion to the screen, while the exposure step had to be controlled to avoid holes that were too small or large with ragged edges caused by light diffraction, ultimately limiting the maximum resolution of large color CRTs.

After the screen is coated with phosphor and aluminum and the shadow mask installed onto it the screen is bonded to the funnel using a glass frit that may contain 65 to 88% of lead oxide by weight. The lead oxide is necessary for the glass frit to have a low melting temperature. Boron oxide (III) may also present to stabilize the frit, with alumina powder as filler powder to control the thermal expansion of the frit.amyl acetate or in a polymer with an alkyl methacrylate monomer together with an organic solvent to dissolve the polymer and monomer.

Due to limitations in the dimensional precision with which CRTs can be manufactured economically, it has not been practically possible to build color CRTs in which three electron beams could be aligned to hit phosphors of respective color in acceptable coordination, solely on the basis of the geometric configuration of the electron gun axes and gun aperture positions, shadow mask apertures, etc. The shadow mask ensures that one beam will only hit spots of certain colors of phosphors, but minute variations in physical alignment of the internal parts among individual CRTs will cause variations in the exact alignment of the beams through the shadow mask, allowing some electrons from, for example, the red beam to hit, say, blue phosphors, unless some individual compensation is made for the variance among individual tubes.

Color convergence and color purity are two aspects of this single problem. Firstly, for correct color rendering it is necessary that regardless of where the beams are deflected on the screen, all three hit the same spot (and nominally pass through the same hole or slot) on the shadow mask.intaglio printed with poor registration. Poor purity causes objects on the screen to appear off-color while their edges remain sharp. Purity and convergence problems can occur at the same time, in the same or different areas of the screen or both over the whole screen, and either uniformly or to greater or lesser degrees over different parts of the screen.

The solution to the static convergence and purity problems is a set of color alignment ring magnets installed around the neck of the CRT.magnetic fields parallel to the planes of the magnets, which are perpendicular to the electron gun axes. Often, one ring has two poles, another has 4, and the remaining ring has 6 poles.vector can be fully and freely adjusted (in both direction and magnitude). By rotating a pair of magnets relative to each other, their relative field alignment can be varied, adjusting the effective field strength of the pair. (As they rotate relative to each other, each magnet"s field can be considered to have two opposing components at right angles, and these four components [two each for two magnets] form two pairs, one pair reinforcing each other and the other pair opposing and canceling each other. Rotating away from alignment, the magnets" mutually reinforcing field components decrease as they are traded for increasing opposed, mutually cancelling components.) By rotating a pair of magnets together, preserving the relative angle between them, the direction of their collective magnetic field can be varied. Overall, adjusting all of the convergence/purity magnets allows a finely tuned slight electron beam deflection or lateral offset to be applied, which compensates for minor static convergence and purity errors intrinsic to the uncalibrated tube. Once set, these magnets are usually glued in place, but normally they can be freed and readjusted in the field (e.g. by a TV repair shop) if necessary.

On some CRTs, additional fixed adjustable magnets are added for dynamic convergence or dynamic purity at specific points on the screen, typically near the corners or edges. Further adjustment of dynamic convergence and purity typically cannot be done passively, but requires active compensation circuits, one to correct convergence horizontally and another to correct it vertically. The deflection yoke contains convergence coils, a set of two per color, wound on the same core, to which the convergence signals are applied. That means 6 convergence coils in groups of 3, with 2 coils per group, with one coil for horizontal convergence correction and another for vertical convergence correction, with each group sharing a core. The groups are separated 120° from one another. Dynamic convergence is necessary because the front of the CRT and the shadow mask aren"t spherical, compensating for electron beam defocusing and astigmatism. The fact that the CRT screen isn"t spherical

The convergence signal may instead be a sawtooth signal with a slight sine wave appearance, the sine wave part is created using a capacitor in series with each deflection coil. In this case, the convergence signal is used to drive the deflection coils. The sine wave part of the signal causes the electron beam to move more slowly near the edges of the screen. The capacitors used to create the convergence signal are known as the s-capacitors. This type of convergence is necessary due to the high deflection angles and flat screens of many CRT computer monitors. The value of the s-capacitors must be chosen based on the scan rate of the CRT, so multi-syncing monitors must have different sets of s-capacitors, one for each refresh rate.

Dynamic convergence may instead be accomplished in some CRTs using only the ring magnets, magnets glued to the CRT, and by varying the position of the deflection yoke, whose position may be maintained using set screws, a clamp and rubber wedges.

Dynamic color convergence and purity are one of the main reasons why until late in their history, CRTs were long-necked (deep) and had biaxially curved faces; these geometric design characteristics are necessary for intrinsic passive dynamic color convergence and purity. Only starting around the 1990s did sophisticated active dynamic convergence compensation circuits become available that made short-necked and flat-faced CRTs workable. These active compensation circuits use the deflection yoke to finely adjust beam deflection according to the beam target location. The same techniques (and major circuit components) also make possible the adjustment of display image rotation, skew, and other complex raster geometry parameters through electronics under user cont