crt to lcd monitors free sample

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ray tubes has essentially halted due to the cost and environmental concerns, CRT-based monitors are considered an outdated technology.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.

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/.

Cathode Ray Tube (CRT) monitors are the most toxic to our environment. Each monitor contains large amounts of lead, along with phosphorous, cadmium, and mercury. Disposal can be quite hazardous if one of the glass tubes breaks and ejects those toxins into the air.

Flat screen monitors (e.g., LCD) offer improvements, but they also can be dangerous to the environment. For example, LCD monitors manufactured before 2009 contain mercury. Plus, recycling PC monitors helps to conserve natural resources and energy, and reduce pollution resulting from the extraction and processing of raw materials from the earth.

Yes! We recycle nearly all business electronics, including computers, printers, copiers and IT equipment. We also recycle consumer electronics, including smartphones, cameras and even stereo equipment. View list of what we recycle at our consumer electronics recycling store.

PC Disposal is part of a family of technology businesses started in 1989. Kory Bostwick founded PC Disposal in 1998 because he was concerned that there were few environmentally-friendly options for companies who wanted to dispose of the toxic glut of obsolete computers that were filling offices – and ultimately – landfills.

With this idea in mind, PC Disposal has grown into one of the largest computer disposal firms in the industry. We"ve now expanded to provide recycling services for all types of electronic waste. In addition to home consumers, our clients include companies of all sizes throughout the United States and Canada, and many of our clients are Fortune 500 companies and U.S. government agencies.

The ScreenScope brings true 3D viewing to your computer screen. It is easily transported and erected, and fits a variety of different computer screens and it also avoids the need for expensive hardware upgrades. It is simple as "Clamp and Play", that is, just clamp it on and start using it.

Unused electronics are the bane of the modern life. Perfectly functional gadgets sit quietly in a corner of the store room, doing nothing. If you"re wondering what to do with old computer monitors, here are a few easy ideas to repurpose unused screens.

In this guide, it doesn"t matter if your old monitor is still working or not. Even if it isn"t, you can use its parts to make a great new gadget. From turning it into a super-tiny computer or dashboard to refashioning into a smart mirror, here are some of the most productive ways to repurpose a computer monitor.

The Raspberry Pi 4 is an incredible device. While it has a wide range of uses, at its core, it is a tiny, low-cost, full-fledged computer. And that means your old monitor can be turned into a PC for less than $60.

Perhaps the best thing to do with an old flat-screen monitor is a DIY DAKboard. The DAKboard is a LCD wall display that shows the current time, weather forecast, calendar events, stock quotes, fitness data, and news headlines. It"s all displayed on a soothing photo. You could buy an official DAKboard, but the makers themselves have shown how to build your own wall display with a Raspberry Pi. when you can build one for far less money and a little geeky fun, the choice is obvious.

Attach your old monitor to a Pi and it can be put in your kitchen as a recipe and video source. Make a Pi-based retro video game console as a treat for your kid (or the kid in you).

Sometimes, you"re working on something private in an open office, or browsing certain *cough* sites *cough* at home. You can"t have your colleagues or kids see what"s on the screen. To keep snooping eyes at bay, make a "your-eyes-only" monitor from an old one.

To anyone else, it is going to look like a blank white monitor with nothing on it. But wearing a special pair of spectacles, you"ll be able to see things on it like a regular monitor. It"s magic! It"s a tough process, but dimovi"s guide at Instructables is thorough and precise.

Basically, you will be cutting out the polarizing film of the old LCD monitor. This film will then be put on a simple pair of glasses. Now your screen appears white, but the glasses can "see" the content. It"s one of the best ways to keep prying eyes out of your PC.

The reason you should use an old computer monitor is that things can go wrong. You will be disassembling and then reassembling the monitor, along with cutting out the anti-glare and polarizing films. You"ll also need to separate the polarizing film from the anti-glare one.

If you have a broken old LCD monitor, it can be re-purposed into a usable mirror; but if you have a working old LCD monitor, adding a Raspberry Pi can turn it into a smart magic mirror!

You can choose from different Raspberry Pi smart magic mirror projects, but for our money, go with the MagicMirror². It"s the original, most popular, and perhaps now the easiest way to build a smart mirror. It comes with a clock, calendar, weather forecast, and news feed.

If you"re on a tight budget for a first-time DIY project, consider the $100 smart mirror. It"s not the best version of turning an LCD monitor into a smart mirror, but you"ll get the basic features and not spend a bomb.

If you have the space available, the best thing you can do with an extra monitor is to boost your productivity with a dual-monitor setup. A second monitor has many potential purposes, such as extended screen space, a dashboard for your social media or news updates, or a dedicated video conferencing screen.

All desktop operating systems support the ability to use dual monitors. It"s pretty easy to setup dual monitors on Windows, and you can then customize how you use the two spaces. To connect two monitors, you will likely need a graphics card with multiple HDMI ports, or use an HDMI and a VGA port on desktops.

Make it a dedicated screen for Nintendo Wii:The Nintendo Wii can connect to a VGA monitor, so if you don"t have a Wii, buy one. In fact, buy a used one, they"re pretty cheap on Craigslist.

Like any gadget, monitors have a limited shelf life. If you"re looking to upgrade, you now have a few ideas of what to do with your old monitor. And that age should influence which project you chose. For example, given the effort involved in building a smart mirror, don"t go with a screen that"s already shown signs of trouble. The Raspberry Pi-based projects are usually the easiest to keep changing.

In fact, if you have an old monitor and old PC parts, you can repurpose the whole PC. You can turn it into a home security system, a home server or media center, or try other unique creative projects.

It"s true. Running modern games on a vintage CRT monitor produces absolutely outstanding results - subjectively superior to anything from the LCD era, up to and including the latest OLED displays. Best suited for PC players, getting an optimal CRT set-up isn"t easy, and prices vary dramatically, but the results can be simply phenomenal.

The advantages of CRT technology over modern flat panels are well-documented. CRTs do not operate from a fixed pixel grid in the way an LCD does - instead three "guns" beam light directly onto the tube. So there"s no upscaling blur and no need to run at any specific native resolution as such. On lower resolutions, you may notice "scan lines" more readily, but the fact is that even lower resolution game outputs like 1024x768 or 1280x960 can look wonderful. Of course, higher-end CRTs can input and process higher resolutions, but the main takeaway here is that liberation from a set native resolution is a gamechanger - why spend so many GPU resources on the amount of pixels drawn when you can concentrate on quality instead without having to worry about upscale blurring?

The second advantage is motion resolution. LCD technologies all use a technique known as "sample and hold" which results in motion rendering at a significantly lower resolution than static imagery. Ever noticed how left/right panning in a football match looks blurrier than static shots on an LCD? This is a classic example of poor motion resolution - something that simply isn"t an issue on a CRT. Motion handling on CRT is on another level compared to modern technologies in that every aspect of every frame is rendered identically, to the point where even a 768p presentation may well be delivering more detail in motion than a 4K LCD.

Then there"s display lag, or rather, the complete lack of it. Imagery is beamed directly onto the screen at the speed of light, meaning zero delay. Even compared to 240Hz LCDs I"ve tested, the classic mouse pointer response test feels different, faster. The advantages in terms of game response - particularly with an input mechanism as precise as the mouse - need no further explanation.

On a more general level, there"s a sense that games and hardware have "grown" into CRT technology over the years. Visuals are more realistic than they"ve ever been, and there"s something about the look of a CRT presentation that further emphasises that realism - aliasing in particular is much less of an issue compared to a fixed pixel grid LCD. Secondly, PC hardware has evolved now to the point where running at higher refresh rates than 60Hz is relatively simple - and a great many CRT monitors can easily run at much faster frequencies, up to 160Hz and even beyond, depending on the display and the input resolution. This is all pretty good for a technology that essentially became obsolete soon after the turn of the millenium.

And that"s where the negatives of CRT gaming start to hit home. The technology is outdated, which presents many pitfalls. The most obvious concerns form-factor: CRT displays are big, bulky and weigh a lot. I invested in a display widely considered to be one of the greatest CRTs ever made - the Sony Trinitron FW900 - a 16:10 24-inch screen. As the video hopefully demonstrates, picture quality is immense, but so is the heft of the screen. It weighs 42kg and with a 600x550mm footprint, the amount of real estate required is not insignificant.

Then there"s the input situation. CRT monitors use VGA, DVI-I or component RGB BNC inputs - and pretty much the most powerful modern GPU still to offer support there is the GTX 980 Ti or Titan X Maxwell. Thankfully HDMI, USB-C and DisplayPort to VGA adapters are available, but you"ll be spending a lot of time online looking for the right one to handle high pixel-rates if you intend to go past 1920x1200 at 60Hz. Very few widescreen CRTs are available and even the Sony FW900 has a 16:10 aspect ratio, meaning that console gaming isn"t really a good fit for CRT displays - 4:3 screens, even less so. Yes, you can run consoles on a CRT, but my feeling is that for many reasons, this is a pursuit best suited to PC users.

Finally, there"s the cost - which can cut both ways - along with the quality of the display you"ll actually get. The FW900 is a legendary screen with massive asking prices to match. However, John Linneman"s 19-inch 4:3 Sony Trinitron G400 cost him just 10 Euros (!) and still looks amazing. However, the fact is that in both John"s case and mine, the screens weren"t in optimal condition when we bought them - which is to be expected for screens well into their second decade of life. Suffice to say, getting image quality to the expected levels can take a lot of time, effort and plenty of research. And on a more basic level, CRT screens are made of glass and glare can be an issue. In shooting the video on this page, I had to film at night in order to show the screen in the best possible light.

There are plenty of pitfalls then - but the end results while gaming are highly satisfactory. Modern titles on a CRT can look sensational, you have the benefits of high refresh rates if you want them, you can turn up all the eye candy and you don"t need to worry so much about resolution as a major defining factor of image quality. Today"s premium-priced gaming LCDs are trying very hard to recapture CRT"s major benefits - low latency, high refresh rates and reduced input lag - but as good as many of these screens are, for our money nothing beats a good old-fashioned cathode ray tube display for desktop gaming - not even the very best LCD screens on the market.

Cathode-ray-tube (CRT) displays have been used extensively in vision research because of their superior response times and reduced motion smear, relative to the liquid crystal displays (LCDs) commonly used in homes and offices. To produce an image on a CRT screen, a stream of electrons is shot at a phosphor-coated screen from an electron gun that can be rapidly turned on or off and repositioned. When hit by the electron stream, the phosphor luminesces for a period that varies with the phosphor’s characteristics. Some phosphors (e.g., P15) have virtually no persistence; others (e.g., P31) have persistence that can remain visible for several seconds (Di Lollo, Seiffert, Burchett, Rabeeh, & Ruman, 1997). LCD screens are based on a totally different technology: A steady light source positioned behind the screen is blocked by a layer of liquid crystals arranged in a matrix of pixels. The liquid crystals act as switches that allow the passage of light when a voltage is applied to them. The amount of light transmitted varies with the input voltage. Until recently, LCD screens reacted sluggishly to changes in input voltage. Recent advances in LCD technology, however, have improved their temporal characteristics, making them potential candidates for the laboratory.

Kihara, Kawahara, and Takeda (2010) have shown that observers exhibit comparable performance with CRT and LCD monitors on two well-known attentional and perceptual tasks: the attentional blink and metacontrast masking. As the authors noted, however, these results do not necessarily demonstrate that LCDs are suitable for all experimental paradigms. For instance, because of phosphor persistence, CRT images are known to remain visible for some time after the initial image has been turned off (Di Lollo et al., 1997; Groner, Groner, Müller, Bischof, & Di Lollo, 1993). It is possible that LCD monitors will produce similar residual images as a result of a delay in shifting from one liquid crystal orientation to another. These residual images, which we refer to as display persistence, were not of critical importance in the paradigms investigated by Kihara et al. because the target stimuli were invariably followed by masks that overwrote any lingering persistence on the display screen. On the other hand, residual images are potentially harmful in paradigms that require precise timing of stimulus offset. One of the objectives of the present study was to investigate the duration of display persistence on both CRT and LCD monitors.

Amongst the paradigms in which display persistence is definitely of concern is the Sperling (1960) paradigm, in which an array of items is flashed briefly on the screen, with observers reporting some or all of the items. Display persistence is also of concern in studies of temporal integration of brief successive stimuli (Irwin & Thomas, 2008). A critical requirement in these paradigms is that there be no residual images left on the screen once the stimuli have been turned off. Otherwise, one might falsely attribute correct performance to persistence in the visual system (iconic memory), when in fact it should be attributed, at least in part, to display persistence. In this case, iconic memory would be inextricably confounded with display persistence.

An example of this type of confounding can be seen in a study by Jonides, Irwin, and Yantis (1982). The principal objective was to determine whether two sequential images displayed at different retinal locations, but at the same spatial location, could be integrated so as to be perceived as a single image. In other words, Jonides et al. (1982) were interested in determining whether temporal integration can occur spatiotopically. The stimuli were similar to those used in a study by Di Lollo (1977), in which a square 5 × 5 dot matrix was displayed with one dot missing at a randomly chosen location. The observers’ task was to report the matrix location of the missing dot. To study temporal integration, Di Lollo displayed the matrix at fixation in two brief successive frames of 12 dots each, separated by a variable interstimulus interval (ISI). At short ISIs, the two frames were seen as a single integrated image, and the missing dot could be located with ease. At longer ISIs, the two frames were perceived as temporally segregated, and the task was impossible.

To study spatiotopic temporal integration, Jonides et al. (1982) displayed the two frames of the matrix at the same spatial location but at different retinal locations. This was done by presenting the first frame to one side of fixation, its onset serving as a signal for the observer to shift his or her gaze to that location. The second frame was then displayed at the same location as the first, after a brief ISI during which the screen was blank. In this display sequence, the two frames were in spatial registration but they impinged on different retinal locations. The finding that the location of the missing dot was reported with considerable accuracy was regarded as evidence for spatiotopic temporal integration.

This conclusion, however, was vitiated by a considerations of phosphor persistence. The phosphor used in the Jonides et al. (1982) study was P4, which has been shown to generate visible persistence beyond 1 s in dark-adapted viewing (Di Lollo et al., 1997). Given such long phosphor persistence, the dots in the first frame were still visible when the second frame was displayed. Thus, integration of the two frames was mediated not by a visual memory of the dots in the first frame, but by their actual presence on the screen because of phosphor persistence. This was later confirmed by Jonides, Irwin, and Yantis (1983), who used light-emitting diodes that are free from persistence and found no evidence of spatiotopic temporal integration.

In fairness to Jonides et al. (1982), industrial specifications of decay characteristics indicated that the relative brightness of the P4 phosphor decreases to 1% of maximum within about 0.5 ms (Bell, 1970). This specification seemed to justify the use of P4 phosphor in the Jonides et al. study. The important message is that, as explained below, photometric estimates cannot be used as reliable guides to the visibility of the persistence of a display.

To avoid the type of confound that flawed the study of Jonides et al. (1982), we need to know the time course of the display persistence visible on a screen after the stimulus has been turned off. That is, we need information about the visibility of display persistence, as distinct from its luminance. The time for which a stimulus continues to luminesce on the screen is typically measured with a photometer. However, such luminance readings do not provide unambiguous measures of visibility. The conversion from luminance values to visibility estimates is complicated by such factors as response compression (Hood & Finkelstein, 1986) and changes in the gain of the visual system arising from rapid neural adaptation. This is an important consideration. Whereas the sensitivity of a photometer is invariant with changes in the luminance of the light source, the sensitivity of the visual system changes rapidly and dynamically with changes in stimulation. The gain of the visual system is known to increase by one log unit within about 100 ms of stimulus offset, and by two log units shortly thereafter (Baker, 1963). For this reason, a stimulus can still be visible shortly after it has been turned off, even though the level of photometrically measured luminance may be regarded as negligible.

Estimates of the visibility—as distinct from the luminance—of display persistence are available for such phosphors as P15 and P31 (e.g., Di Lollo et al., 1997). However, no corresponding estimates are available for the visibility of the persistence of CRT screens commonly used in studies of cognition and perception. The present work provides those estimates.

In the present work, we examined the time course of the visibility of display persistence on both CRT and LCD monitors under light-adapted and dark-adapted viewing. A vertical or horizontal bar was displayed on the monitor behind a closed mechanical shutter. The shutter opened rapidly at varying intervals following the offset of the bar. Therefore, any image still visible on the screen was the result of display persistence. The observers’ task was to identify the bar’s orientation.

A second, and just as important, objective of the present work was to examine the timing of LCD screens. Previous estimates had revealed LCD displays to be sluggish, requiring as long as 150 ms to reach maximum luminance (Liang & Badano, 2007). This slow rise time rendered LCD screens unsuitable for experiments or applications that require brief displays. A recent advance in LCD technology, known as overdrive technology, however, has resulted in substantial reductions in their response times, bringing LCD screens within the range of useful devices.

The principal objective of overdrive technology is to speed the transition from one level of luminance to another, as when a light stimulus is presented on a dark background. Figure 1 illustrates how this is done. Panels a and b show the course of events without overdrive. The two functions in each panel illustrate a shift from a lower level (Level 1) to higher levels (Levels 2 and 3) of intensity. Panel a illustrates changes in the voltages applied to the liquid crystals to achieve and maintain the desired level of luminance. Panel b illustrates the temporal course of the changes in luminance in response to the changes in voltage. Clearly, the sudden increments in voltage (panel a) result in sluggish changes in luminance (panel b). The important thing to note is that the rate of change in luminance is faster for the higher voltage (panel b, segmented line). For example, luminance reaches Level 2 sooner when the voltage is switched to Level 3 than when it is switched to Level 2. This phenomenon is used in overdrive technology to achieve a faster transition between different levels of luminance.

Suppose that the luminance of a stimulus is to be switched rapidly from Level 1 to Level 2. When implementing overdrive, the voltage is initially changed to Level 3 for a single frame, and then lowered to Level 2 (Fig. 1c). The corresponding changes in luminance are illustrated in panel d. Because of the overdrive procedure, the luminance in panel d reaches (and may overshoot) Level 2 within a single frame, as compared to approximately two frames without overdrive (Fig. 1b, solid line). An example of overshoot is seen in Fig. 1d; it occurs when the fast rate of change in luminance associated with the high voltage causes it to exceed the criterial level before the input voltage is reduced to the appropriate level.Part I: Psychophysical estimates of visibility

Stimuli were presented on one of two computer monitors: a 21-in CRT (AccuSync 120 equipped with B22 phosphor, denoted as having “medium-short” persistence, manufactured by NEC: www.necdisplay.com) and a 23-in. LCD (BenQ XL2410T, www.benq.com). B22 phosphor is also known as P22 phosphor. The CRT was set at a resolution of 800 × 600 pixels and the LCD at 1,920 × 1,080 pixels. Both monitors operated at a refresh rate of 120 Hz and were switched on at least 30 min before the beginning of the experiment. The brightness and contrast settings of both display monitors were set to maximum, so as to examine the worst-case scenario for both monitors. The luminance of the stimuli under different viewing conditions is specified below.

Observations were made under two lighting conditions: dark, and ordinary room lighting. The corresponding screen luminance values are specified below. In the dark-viewing condition, the screen was encased within a cover that prevented any screen light from escaping the enclosure. The displays were viewed monocularly with the preferred eye through a mechanical shutter with a 25-mm diameter [Gerbrand Model G1166 (D)/(S)]. The shutter opened from the center out as an expanding circle and was positioned over a small hole in the cover 42 cm from the center of the screen. According to the manufacturer’s specifications, the shutter changes from closed to open in 2 ms. We checked on this with a photodiode and found that the opening delay was close to specification, and never exceeded 4 ms.

The display consisted of a vertical or horizontal light bar presented in the center of a darker background. At the viewing distance of 42 cm, the bar subtended 3.4º × 13.6º (210 × 57 pixels in the CRT monitor, 340 × 90 pixels in the LCD monitor). The orientation of the bar was chosen randomly on each trial, with the constraint that each orientation was chosen an equal number of times.

Each trial began with a 200-ms display of the bar behind a closed shutter. The shutter opened at varying delays following the offset of the bar. In calculating the shutter delays, we took into account the time required for the raster to travel from the top of the screen to the screen location beyond that occupied by the vertical bar. This was done to ensure that the bar had been removed from the screen before the shutter began to open. Given a refresh rate of 120 Hz, the signal to open the shutter was issued 6 ms after the beginning of the raster scan. This was designated as the 0-ms delay. Longer delays were obtained by adding the appropriate temporal intervals. Because of the shutter-opening time, the actual shutter delays were 2–4 ms longer than those shown in the figures. When the shutter opened, the observer attempted to identify the orientation of the bar on the basis of the display persistence remaining on the screen. A total of 48 responses were collected at each combination of lighting condition, monitor, and shutter-opening delay. Stimulus presentation and shutter control were governed by programs written in E-Prime (Version 2.0; Psychological Software Tools, Pittsburgh, PA).

The experiment was conducted in a dark room, and each observer was dark-adapted for at least 30 min prior to the session. The luminance of the white bar on the CRT monitor was 120.0 cd/m2, and the luminance of the black background was 0.2 cd/m2, as measured by a Minolta LS-110 luminance meter. The corresponding luminance values for the LCD screen were 242.1 cd/m2 and 0.2 cd/m2. The range of shutter-opening delays from stimulus offset was set to encompass identification accuracies from near-perfect to near-chance.

The results for the CRT screen, illustrated in Fig. 2, show that the phosphorescence of the CRT screen remained visible (accuracy above 50%) for over 3 s for all observers. Di Lollo et al. (1997) reported similar estimates for P4 and P31 phosphors. In contrast, the display persistence of the LCD screen was negligible, with accuracy hovering around chance even at a nominal shutter delay of 0 (averaged across the three observers, the percentage of correct responses was 49%). We conclude that under dark-adapted conditions, the LCD screen was superior in producing essentially no display persistence, as compared to substantial persistence for the CRT screen.

Dark-adapted viewing of a vertical or horizontal bar displayed behind a closed shutter on a CRT screen: Percentages of correct identifications of the bar orientation as a function of the shutter-opening delay from stimulus offset, displayed separately for the three observers. The dashed line indicates chance level

The above measurements were performed with the brightness and contrast settings of both the CRT and the LCD screens set to maximum. Because these settings resulted in higher luminance for the LCD screen (see above), we replicated the measurements with the luminance of the LCD screen set to match that of the CRT screen. As specified above, the luminance of the CRT was 120.0 cd/m2 for the white bar and 0.2 cd/m2 for the black background. The matching values for the LCD screen were 123.1 cd/m2 and 0.1 cd/m2, respectively. Averaged across the three observers, the percentage of correct responses obtained at the lower luminance setting for the LCD screen was 52%, which was very similar to that obtained at the higher setting. Phenomenologically, the stimuli were never visible on any trial.

The procedures here were the same as in dark-adapted viewing, except that the session was conducted under normal room-lighting conditions. The monitor was not covered with a shield, and participants were not dark-adapted prior to the session. The luminance of the CRT monitor was 123.5 cd/m2 for the white bar and 3.5 cd/m2 for the black background. The corresponding estimates for the LCD monitor were 242.6 cd/m2 for the white bar and 0.8 cd/m2 for the black background. The results for the CRT screen are illustrated in Fig. 3. As expected, the visibility of display persistence was shorter than in dark-adapted viewing (Fig. 2), reaching chance level approximately 125 ms after stimulus offset. Even such relatively short persistence, however, can be harmful when brief exposures are required as in studies of iconic memory and temporal integration. A notable finding was that when the polarity of the displays was reversed (i.e., a black bar on a white background), no persistence was visible even at the shortest shutter delay (averaged across the three observers, the percentage of correct responses at a nominal shutter delay of 0 was 49%).

Light-adapted viewing of a vertical or horizontal bar displayed behind a closed shutter on a CRT screen: Percentages of correct identifications of the bar orientation as a function of the shutter-opening delay from stimulus offset, displayed separately for the three observers. The dashed line indicates chance level

The results for the LCD screen revealed no display persistence even at the shortest shutter delay for either white-on-black or black-on-white displays (averaged across the three observers, the percentages of correct responses at a nominal shutter delay of 0 were 47% and 49%, respectively). As was done in the dark-adapted viewing condition, a separate set of estimates were obtained for the LCD screen with the luminance set to match that of the CRT. As specified above, the luminance of the CRT was 123.5 cd/m2 for the white bar and 3.5 cd/m2 for the black background. The matching values for the LCD screen were 124.0 cd/m2 and 0.9 cd/m2, respectively. Averaged across the three observers, the percentages of correct responses obtained at the lower luminance setting for the LCD screen were 47% for white-on-black displays and 49% for black-on-white displays. These results were very similar to those obtained at the higher setting. Phenomenologically, the stimuli were never visible on any trial.Part II: Photometric estimates of luminance

Earlier estimates of the time to reach maximum luminance in LCD screens have ranged up to 47 ms for black-to-white transitions (Wiens et al., 2004) and up to 150 ms for gray-to-gray transitions (Liang & Badano, 2007). Those estimates, however, were obtained before the advent of overdrive technology, which boosts the voltage applied to the liquid crystals, thereby markedly improving the temporal response characteristics of LCD screens. The present photometric measurements were performed to assess the extent to which the response times were improved by overdrive technology.

The monitors and the stimuli were the same as those used for the psychophysical estimates. The luminance of the stimuli was measured with a photo diode (S7686, Hamamatsu Photonics) calibrated for the human spectral sensitivity function (spectral response range 480–660 nm, peak sensitivity 550 nm), with an active area of 2.8 × 2.4 mm. The photodiode was placed on the center of the screen, and its output was amplified by a Thorlabs PDA200C photo diode amplifier. The signal was sampled at a rate of 25 kHz by a quickDAQ (Version 1.6.0.8) data acquisition system on a laptop computer via a Data Translation DT9804-EC-I USB Data Acquisition Function Module. In preliminary trials, we found that the LCD display reached maximum luminance within a single 8.33-ms refresh frame. To add a margin of safety, each display consisted of two consecutive frames, for a total display duration of 16.7 ms. A total of 100 such trials, separated by 100-ms gaps, were recorded in the data acquisition system. The average of those 100 trials was then smoothed by means of a central-moving-average procedure using 11 data points, 5 on either side of the point whose mean was to be calculated. The measurements were performed in a dimly lit room.

The results for the CRT screen are shown in Fig. 4, which illustrates transitions from black to white for two successive frames. The zero point on the abscissa represents the vertical sync signal initiating the start of the first frame. Because the stimulus was presented in the center of the screen and the plotting rate was 120 Hz (8.33 ms per frame), the onset of the function is delayed by approximately 4.2 ms from the zero point—to wit, by the time it took the raster scan to reach the center of the screen. Using the criteria specified below in Fig. 6, the rise time and fall time of the left-hand function in Fig. 4 were 320 and 480 μs, respectively. These times are similar to those reported by Westheimer (1993) for P31 phosphor. The duration of a single frame, based on the criteria specified in Fig. 6, was 920 μs. It is perhaps worth noting that the small bumps in the function in Fig. 4 starting just after the 20-ms mark are consistent with similar bumps reported by Kihara et al. (2010, Fig. 1b). Since the frequency of these bumps are in phase with the refresh cycle, they are likely to be produced by electrons shot at the screen while the electron gun is held at a subcritical voltage while the screen is nominally black.

Luminance changes produced by a white bar displayed for two refresh cycles on a CRT screen running at 120 Hz. Represented on the ordinate is the strength of the illumination signal (in microvolts) recorded by the photodiode

The results for the LCD screen are illustrated in Fig. 5. Estimates were obtained for a black-to-white transition (RGB 0 to 255) and for two gray-to-gray transitions (RGB 10 to 65 and 25 to 165). As was the case for the CRT functions (Fig. 4), the LCD functions in Fig. 5 are delayed by approximately 4.2 ms from the zero point. This was to be expected, on the grounds that, just like CRT monitors, LCD monitors operate on a raster-scan system.

Luminance changes produced by a light bar displayed for two refresh cycles on an LCD screen running at 120 Hz. Three luminance transitions were tested: one black-to-white transition (RGB 0, 0, 0 to 255, 255, 255, labeled as 0–255), and two gray-to-gray transitions (RGB 25, 25, 25 to 165, 165, 165, labeled as 25–165, and RGB 10, 10, 10 to 65, 65, 65, labeled as 10–65). Represented on the ordinate is the strength of the illumination signal (in microvolts) recorded by the photo diode

The functions in Figs. 4 (CRT) and 5 (LCD) differ substantially from one another in maximum intensity (approximately 200 and 14 μV, respectively). As noted in the Method section, the two screens were set to maximum luminance. This resulted in photometric readings of 120.0 and 242.1 cd/m2 for the CRT and LCD screens, respectively. The photometric measures illustrated in Figs. 4 and 5, however, exhibit the opposite relationship, with the CRT having the greater intensity. This discrepancy can be understood in terms of the different sampling rates used in the measurements. The luminance values of 120.0 and 242.1 cd/m2 were obtained with a photometer that averaged the screen output over a period of about 1.5 s (~0.67 Hz), whereas the intensity values in Figs. 4 and 5 were obtained with a light sensor that sampled the output every 0.00004 s (25 kHz). The important consideration is that any given pixel in the CRT screen was activated only once per refresh cycle (see Fig. 4), whereas the corresponding pixels in the LCD screen emitted light continuously. To yield similar time-averaged luminances, therefore, the electron beam in the CRT needed to have a higher intensity relative to the backlight of the LCD screen. This difference in intensity is reflected in the functions in Figs. 4 and 5.

We estimated three parameters for each of the three functions in Fig. 5: rise time, duration, and fall time, as illustrated in Fig. 6. To compute these parameters, we defined the baseline for each function as the average intensity from the beginning of the measurement to 4.2 ms beyond the zero point. Computation of the rise and fall times, however, was complicated, because the overdrive technology caused a brief overshoot of the asymptotic level in each of the three functions. For this reason, rise time was defined as the time taken for the intensity to change from 10% to 90% of the difference between the baseline and the asymptotic intensity, defined as the average intensity over the last 4.2 ms of the display (i.e., the 4.2-ms period starting 16.67 ms from the zero point). Rise times were 3.0, 3.7, and 4.8 ms for the 10–65, 25–165, and 0–255 functions, respectively.

Duration was defined as the difference between the 10% points in the leading and trailing edges of each function. The estimated durations were 16.9, 17.0, and 17.0 ms for the 10–65, 25–165, and 0–255 functions, respectively. Fall time was defined as the time taken for the intensity to change from 90% to 10% of the difference between the baseline and the asymptotic level. The estimated fall times were 0.6, 1.0, and 1.4 ms for the 10–65, 25–165, and 0–255 functions, respectively.

A taxonomic survey of commercially available LCD monitors was obviously beyond the scope of the present work. To gain some indication of the generality of the findings reported in the foregoing analysis, however, we tested two additional LCD monitors: a Dell 1907FPc (not equipped with overdrive, released February 2006) and a ViewSonic VS12841 (equipped with overdrive, released December 2009). A further reason for testing additional monitors was to ascertain whether the superior temporal characteristics exhibited by the BenQ XL2410T could be ascribed to the implementation of overdrive technology. The three monitors (Dell, ViewSonic, and BenQ) are compared in Fig. 7. The data were collected as described above, with the following exceptions. The stimuli were displayed for 66.7 ms because preliminary results indicated that all of the monitors reached asymptotic level within this time window. The BenQ monitor was refreshed at a rate of 120 Hz (i.e., the stimuli were displayed for eight frames). Because the Dell and the ViewSonic monitors could not reach a frame rate of 120 Hz, they were run at 60 Hz (i.e., the stimuli were displayed for four frames). In addition, the ViewSonic and the BenQ monitors were run with the overdrive feature either ON or OFF. This could not be done with the Dell monitor, which was not equipped with overdrive.

Luminance changes produced by a light bar displayed for 66.7 ms on three LCD screens. (a) Dell 1907FPc, run at 60 Hz; (b) ViewSonic VS12841, run at 60 Hz; (c) BenQ XL2410T, run at 120 Hz. Three luminance transitions, fully described in the Fig. 5 caption, were tested in each monitor: one black-to-white transition (RGB 0–255) and two gray-to-gray transitions (RGB 25–165 and RGB 10–65). The ViewSonic and the BenQ monitors were tested with the overdrive feature turned ON (bold functions) and OFF (thin functions). Represented on each ordinate is the strength of the illumination signal (in microvolts) recorded by the photo diode

The photometric measurements are illustrated in Fig. 7 and Table 1. Clearly, the response characteristics of both the ViewSonic and BenQ monitors were markedly improved with overdrive turned on. It is also clear that the performance of older models, exemplified by the Dell monitor, is inferior to that of more recent models, even with overdrive in the newer models turned off. All functions in Fig. 7 exhibited some 60-Hz fluctuations, most noticeable in Fig. 7a. Similar fluctuations have been reported by Kihara et al. (2010, Fig. 4c) and by Wiens et al. (2004, Fig. 1b). This 60-Hz component is inherent in the LCD power supply and can be much reduced or eliminated by a 60-Hz notch filter on the power cable, by placing the power supply away from the monitor, or by shielding the main LCD circuit board with a sheet of mu-metal.

Table 1 Rise times, fall times, and durations (in milliseconds) for the BenQ XL2410T, ViewSonic VS12841, and Dell 1907FPc LCD monitors, for three RGB transitions and with overdrive turned OFF or ONGeneral discussion and conclusions

The psychophysical estimates are unambiguous: For white images on a black background, the BenQ LCD screen never produced any display persistence, even in dark-adapted viewing, whereas the CRT produced substantial persistence in both light- and dark-adapted viewing. On the other hand, neither monitor produced any measurable visible persistence for black images on a white background. Clearly, when display persistence is a concern, LCD screens are preferable to CRT screens unless the displays consist of black-on-white stimuli.

As compared to photometric estimates obtained with LCD monitors without overdrive or with overdrive turned off (Fig. 7; see also Liang & Badano, 2007; Wiens et al., 2004), the present estimates highlight the substantial improvement in temporal response characteristics brought about by overdrive technology. For example, our estimated rise time of 1–6 ms is considerably shorter than estimates obtained without overdrive (2–25 ms in our estimates, 20–150 ms in past research; Liang & Badano, 2007; Wiens et al., 2004) and approaches that of CRTs (<1 ms). Clearly, recent advances in LCD technology have resulted in a substantial reduction in response times, making LCD screens suitable for presenting brief displays.

Of the many display monitors available commercially, only one CRT and three LCD monitors were selected for testing in the present work. A complete taxonomy of all available monitors would obviously be unfeasible. Alternatively, one might set out to formulate some general rule relating the photometric characteristics of any given monitor to the manufacturer specifications. However, this calculation would be complicated by the fact that manufacturers use different methods and criteria for assessing the temporal characteristics of their displays.

At any rate, knowledge of the temporal characteristics of the display would not provide an estimate of visibility. Ideally, one could attempt to map out the relationship between the photometric estimates of display persistence and the corresponding estimates of visibility. This would provide a look-up table from which the visibility of display persistence could be ascertained from photometric measures. In practice, however, this approach is not viable, because physical measures of light provide only indirect measures of visibility. To be useful in psychophysical experiments, a critical additional step would be required: An estimate of visibility needs to be inferred from the physical measure. Such a conversion is complicated by such factors as response compression (see, e.g., Finkelstein, Harrison, & Hood, 1988) and dynamic changes in the gain of the visual system arising from intensity changes in light input throughout the period of measurement. For example, as noted above, the gain of the visual system is known to increase by one log unit within about 100 ms of stimulus offset, and by two log units shortly thereafter (Baker, 1963). For this reason, a stimulus can still be visible shortly after it has been turned off, even though the level of photometrically measured phosphorescence may be regarded as negligible.

Other considerations in relating visible persistence to physical measures include such factors as the initial luminance of the stimulus, its duration, its visual angle and contrast (Ricco’s law), the ambient illumination, and the level of adaptation to that illumination, to name a few. To be clear, even if one were to use a supremely sensitive photometer, the photometric reading would not be an index of visibility: The visibility of the signal could be determined only by means of the kind of psychophysical procedure described in the present work. Perhaps the safest course will be to use the method described in the present work to obtain the required information for the specific display equipment used in any given investigation.

Unless you’ve been following the less mainstream tech conversations going on these days, you might have missed a renewed discussion on the merits of CRT or cathode ray tube screens. Yes, we’re talking about the original ‘tube’ that has now been all but replaced by various flat panel technologies.

Believe it or not, there’s an entire generation of people who have probably never seen a CRT in real life! So why are people in tech circles talking about this older technology today? What are CRT monitors used for? Isn’t modern display tech superior?

One of the biggest drawbacks of flat panel screens is that they have a “native” resolution. In other words, they have a fixed, physical grid of picture elements. So a full HD panel has 1920 by 1080 pixels. If you send an image with a lower resolution to such a panel, it has to be scaled so that multiple physical pixels act as a single virtual pixel.

In the early days scaled images on an LCD screen looked absolutely awful, but modern scaling solutions look great. So it’s not much of an issue anymore.

Still, images on a CRT look good at any resolution. This is because there are no physical pixels using this display technology. The image is drawn on the inside of the screen using electron beams, so no scaling is required. The pixels are simply drawn at the size they need to be. So even relatively low resolution images look nice and smooth on a CRT.

In the past this was a good way to gain performance in 3D apps and video games. Simply lower the resolution to get a smoother experience. With the advent of LCD technology you pretty much had to output at the native resolution, which meant cutting corners in other areas such as texture and lighting detail.

Using a CRT for high-end 3D applications means you can cut the resolution, keep the eye candy and get good performance. With almost no visual hit compared to doing the same thing on an LCD.

LCD flat panels use a display method known as “sample and hold”, where the current frame stays on screen in a perfectly static way until the next one is ready. CRTs (and plasma screens) use a pulsed method. The frame is drawn on screen, but immediately begins to fade to black as the phosphors lose energy.

While the sample and hold method might sound superior, the perceptual effect is a blurry image in motion thanks to the way we perceive apparent motion. Sample and hold is not the only cause of unwanted motion blur on LCDs, but it’s a big one.

Modern screens either use some form of “motion smoothing”, which leads to the dreaded “soap opera effect” or they insert black frames between the regular ones which causes brightness reduction. CRTs can show sharp motion with no brightness sacrifice and can therefore look much better when playing back video.

Due to the way LCDs work, it’s essentially impossible to display true black in an image. An LCD panel consists of the LCD itself, with its array of color-changing pixels and a backlight. Without the backlight, you won’t see the image. That’s because LCDs don’t give off any light of their own.

The problem is that when a pixel switches off to display black, it doesn’t block all the light coming from behind it. So the best you can get is a sort of grey tone. Modern LCD screens are much better at compensating for this, with multiple LEDs evenly lighting the panel and local backlight dimming, but true blacks are still not possible.

CRTs on the other hand can display blacks almost perfectly thanks to how it draws the picture on the back of the screen. Modern technologies like OLED does nearly as well, but is still far too expensive for mainstream consumers. Plasma was also very good in this regard, but has been largely phased out. So right now in 2019 the best black levels are still to be found in CRTs.

If you like consuming retro content, which includes old video games from before HD consoles and standard 4:3 aspect ratio video content, it may be best to watch them on a CRT.

It’s not that consuming this content on a modern flat panel is bad by any measure, it’s just not what the creators were using as a reference. So what you see will never match their intentions exactly.

Some video games actually took advantage of CRT quirks to generate effects such as flowing water or transparency. These effects don’t work or look odd on modern flat panels. Which is why CRTs are popular and sought after among retro gamers.

While there are plenty of ways in which CRTs are objectively superior to even the best modern flat panel displays, there’s also a long list of cons! After all, there’s a reason the world moved to newer display technology.

It’s also important to remember that flat panel displays at the time of the shift were far worse than those of today, yet people felt the pros of LCDs were on balance a better deal.

CRT screens are huge, heavy, power-hungry and less suitable for productivity and watching widescreen films. While their resolution limits aren’t a huge issue for video games, any sort of serious work turns into struggle with low resolution text and a lack of desktop real estate.

Despite their large size, actual screen dimensions are tiny relative to flat panels. There certainly isn’t a CRT equivalent of the 55” and larger monsters we have today. Despite the substantial image quality and motion advantages CRTs have over even the best modern flat panels, only a small niche group of people are willing to put up with the long list of drawbacks that come with CRT use.

"Between 0.0001 and 0.00001 nits" "Sony claims an OLED contrast range of 1,000,000:1. When I asked how the contrast could be so high I was told that the surface is SO black the contrast is almost infinite. If the number representing the dark end of the contrast scale is nearly zero then dividing that number into the brightest value results in a very, very high contrast ratio."

Does not normally occur at 100% brightness level. At levels below 100% flicker often occurs with frequencies between 60 and 255 Hz, since often pulse-width modulation is used to dim OLED screens.

No native resolution. Currently, the only display technology capable of multi-syncing (displaying different resolutions and refresh rates without the need for scaling).Display lag is extremely low due to its nature, which does not have the ability to store image data before output, unlike LCDs, plasma displays and OLED displays.

Colored sub-pixels may age at different rates, leading to a color shift. Sensitive to UV light from direct sunlight. Is considered the highest quality but also the most expensive display technology currently produced, with products rarely being available for less than $1200.

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One of the largest recycling problems faced by most countries comes down to the sheer volume of computer electronics that are obsolete and outdated. With technology advances showing no signs of slowing down, it"s no wonder that businesses and home users are constantly upgrading computer monitors.

It"s easy to say that you should be recycling old electronics because it"s the right thing to do. But it"s far more important to understand the fundamental impacts that electronics have on our world when they end up in the trash.

The first thing that"s important to understand is how big of a problem electronics are. With people replacing phones every year and computers every few years, it shouldn"t come as a surprise that there are mountains of discarded electronics every year.

When e-waste like monitors isn"t properly handled at the end of its life, then exposure to the natural elements alone can cause many of the toxic materials to break down and evaporate into the air.

But even modern LCD monitors contain many different metals and chemicals that are perfectly safe when they are contained. But even small amounts of th