What components make up the image on my monitor?
The monitor image is made up of several components, surprisingly the monitor's capabilities are usually not the limiting factor in determining what is displayed. The hardware that limits the image you see is usually the video controller (video card).
The components that make up an image are:
a. Resolution - Standard PC resolutions are 640 x 480, 800 x 600, 1024 x 768, 1280 x 1024 and 1600 x 1200. Standard Macintosh resolutions are 640 x 480, 832 x 624, 1152 x 870. Newer Macintosh models can run most standard PC resolutions as well. While a monitor may be capable of displaying any or all of these resolutions, the recommended resolution for monitors is usually lower than the maximum resolution it is capable of displaying.
The higher the resolution displayed on a monitor, the smaller the individual characters and images will appear. Windows® compensates for this by offering a large font option in its setup function. Recommended resolution by CRT size is: 14" - 640 x 480, 15" - 640 x 480 or 800 x 600, 17" - 800 x 600 or 1024 x 768, 19" - 1024 x 768 or 1280 x 1024, 20" - 1024 x 768 or 1280 x 1024, 21" - 1280 x 1024 or 1600 x 1200.
b. Vertical Refresh Rate - VESA (Video Electronics Standards Association) sets standards for vertical refresh rates at certain resolutions. Standard vertical refresh rates are 60 Hz, 70 Hz, 72 Hz, 75 Hz and 85 Hz. Most monitors are capable are running at refresh rates that fall in between (i.e. 73.6 Hz) or higher (i.e. 100 Hz) than these numbers. Using one of the standard refresh rates simplifies monitor set up since monitors contain many of the VESA standards as presets. The plug and play function normally selects one of the VESA standards when it sets up the monitor. A "flicker-free" refresh rate is usually considered to be one that is 72 Hz or higher.
c. Horizontal Refresh Rate - The horizontal refresh rate is usually the limiting factor of the monitor in determining which vertical refresh rate the monitor runs at. The monitor's horizontal refresh range can be either continuous (30 - 70 kHz) or preset (31.5/35.5/38/48 kHz), the actual numbers will vary depending on the monitor's specifications. Presets are usually setup to match the VESA standard resolutions that a monitor can display so preset is not inherently inferior to continuous.
d. Color Depth - Most color monitors can display an unlimited number of colors. Color depth is measured in the number of bits of color that are being displayed. One-bit color displays 8 colors. Popular color depths are 16 color (4-bit), 256 color (8-bit), High Color (16-bit) and true color (24- and 32-bit). The human eye cannot perceive even the number of colors displayed in High Color, but if viewed side by side subtle improvements can be seen between 16-, 24- and 32-bit depths. Because of the large installed base of older systems many games and Internet pages are built to view in 256 colors. High Color is usually more than adequate for most applications. The amount of RAM on the video card determines the color depth you can use at a specific resolution. To get a rough estimate of the amount of RAM needed to display the desired color depth you take the number of pixels in the resolution multiplied by the color depth desired divide by 8 and then divide by 1,024,000 (i.e.((1024 x 768 x 16-bit)/8)/1,024,000 = 1.57 Mb of RAM needed).
How do I program the resolution and refresh rate on my monitor?
You cannot change the resolution from the monitor; the video controller (video card) software controls resolution. Windows, OS/2 and Mac OS contain resolution control utilities that can be used to set up your display. Also, many video cards come with software utilities that assist in setting up your display. Please consult your operating system or video card user manual for information on setting up your display.
What resolution should I run in?
That is a personal decision. It is based on a few factors: The screen size of the monitor, the type of productivity you need and your own comfort. The higher the resolution, the smaller the elements (icons, fonts, gadgets and borders) on the screen. A higher resolution screen makes everything proportionately smaller, allowing more things (open group windows) on the screen at one time. It also allows a wider view of the work without scrolling. However, on a small screen, this may not be comfortable, and it is important to avoid eyestrain and headaches.
What does the degaussing do?
The purpose of degaussing is to demagnetize the shadow mask or aperture grille to allow the electron beams to pass freely through. Most monitors automatically degauss when switched on, and many have manual degaussing buttons. To find out if your monitor has this feature check the user's manual or manufacturer's data sheet. When you manually degauss a monitor the image will wobble for a moment indicating that the degaussing circuit is working. If the purity does not clear up wait at least 10 minutes before degaussing again to allow the degauss circuitry to recharge. If the purity problem persists a qualified technician can degauss the monitor with a special tool.
I have faint ghosts to the right of my icons. Is my monitor bad?
No. The likely cause is that you are using an extension cable added to the video cable that came attached to the monitor. This happens because the video card cannot drive the monitor properly with through the extension. This is called impedance mismatch. If extending the cable is necessary, you need to purchase a video distribution amplifier, available from video equipment suppliers. If you are not using an extension, test the monitor on another computer.
The power light on the monitor is working but there is no picture on the screen. Why is this?
Turn contrast and brightness to full. If you see a faint gray color appearing on the screen, the monitor is functioning properly but not receiving any signal from the video card. If you do not see a faint gray color contact Technical Support for assistance.
The edges of my display seem to vibrate or quiver rapidly. What causes this and what can I do about it?
You may be experiencing what is called non-synchronous jitter. Non-synchronous jitter is normally caused by interference to the monitor from another electrical source near the monitor. The effect may be constant or intermittent, depending upon the characteristics of the source. Constant jitter is usually caused by a large power source near the monitor. Intermittent effects are caused when other devices are turned on or off. Possible sources of interference are: power base with plugs and switches, printers or other peripherals containing a power transformer, power strips, fluorescent lights, appliances containing motors, wiring inside walls or floors or ceilings, electric meters or power panels.
The user can verify that the effect is due to external influence by doing the following:
1. Change the refresh rate of the resolution exhibiting the effect to that of the line frequency (60Hz). This is done by running the Video Adapter utility software and using a custom monitor setup. If this proves to greatly reduce or eliminate the effect, then they are on the right track. They may then revert back to the previous refresh rate and move to the next step.
2. Turn off all possible sources of magnetic influence. If the effect is reduced or eliminated, they can begin restoring power, one device at a time to identify the influencing apparatus.
3. Relocate equipment as required, to result in the best reduction or elimination of the effect.
I have a splotch of color in a corner of the display. What can I do?
The CRT has picked up a bit of magnetism which is causing a purity problem. Normally, the internal automatic degaussing circuit, which operates each time the monitor is powered on, will clear this up.
If this does not clear up the purity problem look for source of interference such as speakers or anything with a magnet, transformer or motor in it (Electric clock, cordless phone charging base, etc.) and move it away from the monitor. If you see a reduction in the effect at that time, you have located the source of the problem.
Once you have removed the source of the interference press the manual degauss button on the front of the monitor. Repeat the application, if needed, about once every ten minutes (the degauss circuitry needs time to recharge) until the discoloration has cleared up. When you press the manual degauss button, you will observe a wobble of the picture for about one second, letting you know the degaussing circuit is working. If repeated attempts do not clear up the discoloration, a Service Technician can manually degauss the CRT with a special device just for this purpose.
My monitor changes colors once in a while. What can I do?
The problem may be due to any component in the video chain. Please do the following:
Reseat the video card.
Make sure the video card contacts are not oxidized.
Make sure the signal cable pins are not damaged.
Make sure the signal cable is securely grounded to the video card and monitor.
If this does not clear up the problem, try another video cable if your monitor has a removable cable. If your monitor has a captive video cable, contact Technical Support for further assistance.
Why isn't my image perfect?
Perfection in monitors is a relative term. Monitors are designed to provide a balance between cost and performance. Every monitor that leaves the assembly line is "perfect" based on the standards and tests that are performed on it during the manufacturing process. That perfection may be marred during transportation, handling and setup of the unit. In addition, many external factors can affect the monitor image including, but not limited to, the video controller, electromagnetic fields in the work environment and the earth's magnetic field. Over time wear and tear on the monitor will also take its toll on the image.
Each monitor model is subject to a certain set of standards that includes measurements of screen geometry. These measurements are actually a range of numbers that vary by as much as ±30% depending on the measurement and where it is taken. Please remember that these measurements must be taken on the CRT itself and not relative to external factors such as the monitor bezel, and that they must be taken on a monitor that has been adjusted to the best image possible.
In addition, you will see different "imperfections" at different resolutions. Changing resolution will help determine if there is a problem with the monitor or if the problem is caused by one of the other links in the image chain.
The following provides answers to many commonly asked screen geometry questions and provide basic troubleshooting steps to determine if the monitor is within factory specifications.
Early in monitor history, the ability to expand the image "edge-to-edge" indicated a high performance monitor. As monitor technology advanced this ability became easier to achieve and today most monitors are capable of "edge-to-edge" or nearly "edge-to-edge" images.While in the past expanding a monitor's image "edge-to-edge" provided for larger features in the display, this is not always desirable in today's Graphic User Interface environment when window control buttons are often located very close to the edge of the image. Increasing image size "edge-to-edge" could actually cause some control buttons to be hidden behind the bezel. It is still important to utilize as much of the monitor's display area as possible. Achieving maximum usage is a combination of the monitor's and video controller's capabilities. An "edge-to-edge" display is not necessarily desirable or achievable (especially with Macintosh timings) in every resolution.
The term "edge-to-edge" is defined relative to the edge of the bezel. Many monitor manufacturers are maximizing the size of the bezel opening allowing users to take advantage of technological advances in monitor design which allows the image to be expanded to utilize a larger portion of the raster. A larger opening means a larger image size, but it may also mean that the monitor is not "edge-to-edge". In this instance being "edge-to-edge" is not important since the user gets the maximum image size possible. Some monitors that are "edge-to-edge" actually have a smaller maximum image size that those that are not since the bezel of the "edge-to-edge" model actually covers usable image area.
The edges of my display are not straight. Is this the fault of my video card?
Not necessarily. Please be make sure that the video card has been set up properly, including the vertical refresh rate. If the problem persists, it may be due to normal manufacturing variances in the monitor. While edges of the image may not be straight when viewed relative to the edge of the bezel (the cutout in the front of the monitor), this does not necessarily indicate a problem as long as the image closer to the center of the monitor are straight.
Why is one edge of the image lower than the other edge?
The earth's magnetic field may be interfering with the magnetic field generated by the monitor causing a slight rotation of the image. To have the best alignment, orient the monitor so that when sitting in front of the monitor, you are facing a westerly direction and the monitor is facing east. As a guideline, there may be approximately up to an 1/8" rotation allowed when viewing a solid background image at full screen size. Some models have a Tilt/Rotation control that allows the user to compensate for minor variances.
Why do the characters in the corner of the screen look fuzzy?
Because CRTs are not perfectly spherical and the electron gun is not located at the end of the ovaloid described by the surface of the CRT the focus on the screen will not be uniform. Circuitry in the monitor or the design of the CRT compensates for some of this variance. The monitor is adjusted so that the focus is best in an area around the center.
When I have a white background up, such as in a word processor, some areas of the screen are a little darker than the center. Is my monitor bad?
The monitor is not bad. The electron beams pass through either a shadow mask or aperture grille which aims them at the proper phosphor color. In high resolution displays, these beams are focused to a fine point, and are slightly smaller than the opening through which they must pass. Nearer to the edges of the tube, the beams may not pass through the exact center of the opening, and part of the beam is blocked. This is called eclipsing. The result is that less beam area strikes the phosphor, and the illumination there is less than that at or near the center of the CRT. This is not an uncommon situation, and the term used is brightness uniformity. Up to 30 percent less illumination than the central area is considered acceptable. Brightness uniformity should not be confused with purity, as discussed earlier.
The picture on my display curves in near the bottom on one side. I have tried the Pincushion and Trapezoid controls, but I can't get that curve out. What can I do?
The component that sweeps the electron beam across the face of the CRT is called the yoke. It resides on the neck of the CRT and has magnetic windings for vertical and horizontal deflection. The electron beams cannot be made to give absolutely perfect geometry at the edges. In addition, different resolutions cause different geometric behavior. To compensate for these variations, the monitor includes circuits and controls to adjust the sides of the display. To keep costs reasonable, these functions are somewhat coarse. To add more functions and finer control, the monitor circuits need to be much more complex, and therefore add to its cost. The area of the display inward of the edges is not subject to these distortions, and it is recommended that the user adjust the geometry controls for the best overall effect.
The color on my monitor is washed out. What can I do?
First, properly adjust the brightness and contrast. If you still feel that the colors are washed out then, if your model has color control, select one of the other temperature settings or adjust the RGB color balance. Unlike televisions, monitors do not have a color level control to control overall color. Once the monitor is properly adjusted reducing the brightness will also saturate colors, but reduce overall picture intensity slightly.
Note : this article was prepared with information from MAG Innovations.
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