Monitors Terms:

Active timing

This is defined as the portion of the Video Signal that carries the actual Video information. Surrounding this region, is the front porch and back porch.

Actual Image Size

The size of the display on the screen is dependent upon the timing signals provided by the video card. The displayable diagonal linear measurement can vary based on the graphic mode being generated and how the monitor responds to the characteristics of the signal.

Bandwidth

This is a qualitative term used to describe the monitor's Video amplifier potential performance. The higher the pixel rate (or format number), the higher the Bandwidth required of the Video Amplifier.

Barrel

An outward bowing of the picture.

Brightness

Light output measured at the face plate of the CRT; typically measured in foot lamberts (Fl). A minimum brightness level of 20Fl when viewing at full page size is considered acceptable.

Character matrix

The total number of Horizontal and Vertical spaces required per character.

CIE Coordinates

The CIE Coordinates for any color are obtained from a CIE Color Chart.

Color Balance

The ability of the monitor to show and maintain the same color when switching or varying the intensity of the screen.

Convergence

The ability of the electron beam to hit precisely the correct phosphor dot.

CRT

This abbreviation stands for Cathode Ray Tube, also known as picture tube or screen. The picture tube in a home TV is also a CRT.

Diagonal Linear Measurement

"Official" screen size is the diagonal measurement of the CRT before its mounted in the monitor cabinet. Some monitor CRT category sizes are 14", 15", 17", 19", and 21".

Dot Pitch

The distance between the one phosphor dot and the nearest dot of the same color in the line above or below.

Flicker

Lit condition of the display caused by mismatch of phosphor and Vertical refresh when the phosphor begins to decay prior to being refreshed giving the display the appearance of "flashing".

Focus

Sharpness of a pixel or series of pixels on the CRT face plate. Also measured as the spot size.

High voltage regulation

Ability of the high voltage to respond to changes in beam current. Good high voltage regulation means a stable display even when changing between different intensity levels.

Horizontal Frequency

This indicates how long it takes to scan each of the Horizontal lines that make up the display. The unit of measurement is kilohertz (kHz). It is directly related to the number of lines and the Vertical Refresh (Frequency) so that the higher the Vertical Refresh or the number of lines, the higher the Horizontal Frequency required. For example,

Format	Vertical Refresh	Horizontal Frequency
640x480	60 Hz	31.5 kHz
640x480	72 Hz	37.8 kHz
800x600	60 Hz	38.7 kHz
800x600	72 Hz	46.4 kHz
1024x768	60 Hz	48.8kHz
1024x768	72 Hz	58.5 kHz

Interlaced

Method of significantly increasing data densities at conventional Horizontal scan rates. Half the image is refreshed (every other scan line) to produce a field. Two fields are refreshed at rates of 87 Hz forming one 43.5 Hz frame. Causes flicker on the display.

Linearity

Comparison of a character size to the size of adjacent characters.

Magnetic Field Effects

As described in the paragraph "Rotation Control", the Monitor is affected by magnetic fields. If your screen develops wrong colors in areas or the picture becomes distorted you must check what is near to your Monitor. If your Monitor is positioned near a steel cabinet, on a steel desk or bench, or a steel girder imbedded in a wall or ceiling, then all of these things could be magnetized and therefore interfering with the picture tube's Electron Beams. Try moving the Monitor two to three feet away from the suspected source of magnetic field and see if the picture improves.

If the picture only looks colored or distorted during certain times check if you have any speakers near the Monitor because these could radiate magnetic fields strong enough to distort the picture when they are powered-up.

Maximum Viewing Area

The actual maximum viewing area is dependent upon the size of the plastic or bezel around the CRT. Typically, the maximum possible for a "17-inch monitor" is actually 15.75 inches plus or minus 1/2 inch. In other words, plus or minus 0.25 inches at the ends of the diagonal measurement.

MPRII

The Swedish National Board for Measurement and Testing (SWEDAC) require that products sold in Sweden comply with a set of safety standards known as MPRII, that covers the levels of magnetic and electrical fields in both the VLF and ELF ranges. It is worth noting that there are no scientific studies that conclude that measurements above MPRII levels are hazardous. To measure emissions, a sophisticated testing area that screens out background radiation needs to be in place. Since distance to the CRT and orientation of the measuring device effects measurement, precise placement of the measuring device is essential and difficult to repeat. For the MPR standards, 48 different locations around the monitor need to be measured. In addition, the actual image displayed can have an impact on emissions so that a given set of measurements may not predict the emissions a user would actual encounter.

SWEDAC MPRII Standard

Magnetic Fields	ELF (5 Hz-2 kHz) VLF (2 kHz-400 kHz)	< 250 nT < 25 nT	nT = nanoTesla 250 nT = 0.00000025 Tesla 1 Tesla = 1 Newton/Ampere Meter V/m = Volts per meter
Electrical Fields	ELF (5 Hz-2 kHz) VLF (2 kHz-400 kHz)	< 25 V/m < 2.5 V/m

Recommendations for Comfortable Viewing

1. Sit at least an arm's length away from the screen. It will reduce eye strain and the low levels magnetic and electrical fields referred to above reduce by the square of the distance, i.e., if you increase the distance by two you reduce the field by four.
2. Leave a distance of at least 2-3 feet from the back of a neighboring monitor if this is possible. The fields are lower at the front than at the rear of the monitor.
3. Adjust the Contrast and Brightness Controls for confortable viewing for three reasons. One, it reduces eye fatigue, two, the picture tube will last longer, and three, all field and emission strengths are related to the brightness of the picture.

Orthogonality

A deviation from true perpendicular of the vertical.

Parallelogram

A deviation of the sides from the true vertical.

Persistence

Phosphor characteristic consisting of the ability to emit light after excitation current of electron beam is removed.

Phosphor

Chemical compound that emits light while being excited by electrons.

Pincushion

An inward bowing of the video image. All monitors experience slight amount of pincushion distortion. The manufacturer has a guideline on what the specification is for each model. The pincushion changes per resolution and also according to the size of the image. Pincushion is similar to bowing or barrel distortion.

Purity

The ability of the electron beam to hit precisely the correct phosphor color dot. If a full page of red color is shown on the display, impurity would result in a purple or greenish color region. This impurity can occur if the shadow mask has been damaged or if the screen has become magnetized. Degaussing the screen may fix the problem.

RMA number

Return Authorization Number. This is a number issued to you from our Customer Service department used to track you monitor.

Real World Screen Size

Starting out with a 17" monitor, adding the bezel, and then having a border around the actual video image may result in a diagonal picture size of only 14". With new technology, there is a way to increase the viewing size but there are some limitations.

Tilt

The angle of the CRT with respect to the horizontal mounting bracket of the chassis. Tilt can vary depending on the monitors orientation to the Earth's magnetic poles. Monitor manufacturers orient and align their products in the Eastern direction. When the monitor is facing a north/south direction, there may be a slight rotation of the image.

Refresh rates

An ergonomic issue that is directly related to long term ease of use. A higher refresh rate translates to a more "flicker" free display. Bandwidth, horizontal and vertical scanning rates depict a monitors ability to provide a higher resolution and refresh rate.

Resolution

The number of pixels or dots per linear distance, dots per inch (DPI).

Uniformity

Comparison of one area's brightness to an adjacent area. In general, the brightest part of the image will be in the center area. When moving out to the edges, the intensity of image will vary in a non-linear function. This means that one corner of the screen will not be the same brightness as another corner of the screen. A typical CRT manufacturer's specification may call for up to a 30% difference between the center area and the corners.

Vertical Frequency

This indicates how many times per second the monitor can draw all the lines on an entire screen. A higher Vertical frequency or Refresh rate will produce less flicker.

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