IN1403 User’s Manual
16
CRT displays: Selecting the optimal refresh rate
CRT displays may tend to flicker at refresh rates below 70 Hz In order to achieve a solid, flicker-free
image, an output refresh rate of 72 Hz or 75 Hz is recommended for most CRT displays. You should
also experiment with even higher refresh rates to see if they create a better image. In some cases, you
will find that the image suddenly appears better at a higher refresh rate, such as 85 Hz
Keep in mind that as the refresh rate is increased, the horizontal scan rate also increases. This places
greater higher bandwidth demands on the video distribution system and the display device. If you
select a refresh rate that is too high you will actually see a softer image because the signal is exceeding
the bandwidth capabilities of the display device. Extremely high refresh rate settings may also create
a compatibility problem because a very high refresh rate may result in a signal that is outside the
compatible scan rate of the data display.
Fixed pixel displays: Selecting the optimal resolution and refresh rate
Display devices based on LCD, DMD, D-ILA/LCOS, or plasma technology have a specific number of
display elements, or pixels. This is also referred to as the "native resolution" of the display device.
These devices are usually capable of showing higher or lower resolution signals, but can only do this
by scaling the image up or down to the native resolution. In order to avoid additional image scaling it
is important to know the native resolution of your display device.
Check your operation manual or the chart on page 17 to determine the native resolution of your
display device. The video scaler output should be set to match this native resolution. The video scaler
output refresh rate should be set to 60 Hz with most LCD, DMD, LCOS, and plasma displays. Higher
refresh rates are not recommended with these display technologies because they usually do not
improve the image and may actually cause compatibility problems.
