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| 1. LCD Display Characteristics and Adjustment Tips |
| (1) |
In some cases (monochrome) LCD displays will have certain "white" pixels
(pixels that remain permanently ON) or "black" pixels (pixels that remain permanently OFF). These white or black
pixels may or may not be visible on the display, depending on the colors used on the screen. This is a typical LCD phenomenon
and does not mean your display is defective. At this time it is impossible to produce displays that are completely free of
these unchangeable white and black pixels. |
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| (2) |
Depending on the ambient temperature, LCD displays may sometimes look whitish
(at high temperatures) or blackish (at low temperatures). Furthermore, due to heat radiating from the LCD's backlight, one part
of the LCD display (where the backlight is installed) may look more whitish than the rest of the screen. Please understand that
this is normal and not a symptom of any defect or failure. |
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| (3) |
The viewing angle of an LCD display is defined using the term "contrast ratio", which is
explained below. (For information on Pro-face display viewing angles, please refer to each model's specification data.) |
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Example:
The Pro-face GP577R-TC11 unit's viewing angle is defined by viewing positions where the contrast ratio (CR) is 150 or higher.
The Pro-face GP3750T unit's viewing angle is defined by viewing positions where the contrast ratio (CR) is 250 or higher.
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As mentioned above, viewing angle is defined using only the contrast ratio. However, even
within this standard viewing angle, the colors or tones on the display panel may look different from the real
color/tone, or they may become invisible, depending on the combination of displayed colors (background color, text color
and switch color). For example, if the background color is bright and you look at the screen from below, the colors may
appear inverted so that the text color and switch color darken to the point where they become invisible. Or, when the
background color is dark and you look at the screen from above, the colors may again appear inverted, so that the text color
and switch color brighten to the point that they become invisible. As a result, be sure to choose your screen colors carefully,
so they produce an effective combination for the LCD panel's operation environment. |
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| (4) |
Often the viewing angle of an LCD display in the vertical plane (from above or below) is
fairly narrow. Also, when viewed from below, LCD displays that have a narrow viewing angle can be seen clearly when you
are close, but then become harder to read as you move further away. Therefore, be sure to install your LCD display at a
height and in a direction that provides the best viewing angle. |
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| (5) |
The brightness and colors/tones of LCD displays vary slightly from one unit to
another. Therefore, if two or more panels are placed close together, differences in brightness and color tones may be visible.
Please understand that this does not mean the LCD is defective or damaged. |
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| (6) |
Displaying a single image for long periods can cause an afterimage to remain when the display
is changed to another screen. To prevent this effect: |
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Use the GP's "Stand-by Mode", which automatically turns the screen OFF when there
is no input for a specified period of time. |
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Do not display any single screen for an extended period of time. Try to periodically change
the screen display. |
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| (7) |
When using a color STN panel or monochrome LCD panel, the following may occur. |
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The display flickers. |
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Screen brightness is uneven. |
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Shadow lines (crosstalk) appear as extensions of straight lines. |
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If you notice any of these phenomena, use your unit's contrast control to adjust the
display (see your display's user manual for details). This may improve
or even correct the problem. Since it normally takes from 10 to 20 minutes for an LCD's brightness to stabilize
after the power is turned on, be sure to adjust the contrast only after the brightness has stabilized. Note also
that the severity of the above-mentioned phenomena will vary according to the display colors used. For example, using
neutral tones will tend to accentuate any display flicker and color unevenness. |
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| (8) |
The display of the TFT panel may flicker.
For TFT panels, flicker can be found using a combination of specific colors (such as stripes with neutral tints and black). |
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| (9) |
In recent years, LCD backlight brightness has increased to 200 cd/m2 and beyond. Nonetheless,
these panels can not be used in direct sunlight. Note also that early morning or late afternoon sunlight may make an LCD
display difficult to read. Be sure to consider these points when selecting your GP's installation location. |
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| (10) |
Since a backlight is a consumable item with a finite lifetime, be sure you replace it
periodically, especially after long periods of continuous use. As a yardstick, the usage life of a backlight
(i.e. when its brightness has fallen to 50% of the initial level) is as follows.
Examples:
GP-577RS: approx. 2.9 years (continuous use at normal temperature)
GP-577RT: approx. 4.6 years (continuous use at normal temperature)
AGP-3000 series : approx. 5.7 years (continuous use at normal temperature) |
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| (11) |
Caution: Even if the screen goes blank due to a backlight failure, or for any other reason,
the unit's touch panel may still be operating normally. Therefore, be sure to design your operation system
(GPs, PLCs, etc.) so that the PLC or any related unit does not malfunction due to a person accidentally touching
the blank screen and sending input signals to the PLC. |
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