When using for one year or more time, small dark dots sometime display on the picture of traditional LCD projectors. This is caused by its open cooling system.

In 2019, HTP firstly adopted Semiconductor refrigeration technology on projector cooling system and developed first generation enclosed projector optical engine. This technology is awarded new patent that year.

Now, HTP 6 series enclosed projector optical engines used for different projector models. These optical engine are widely used for HTP projectors, also used for OEM brand projectors.