The advent of passive 3D display technologies has delivered consumers a choice between passive and active 3D glasses and the associated opposing 3D TV technologies. In this article we look at the advantages and disadvantages of each.

Passive 2D Glasses

Passive 3D glasses, as implied by their name, do not need to be powered to view 3D content. Two types of passive glasses are anaglyph (one red and one cyan lens) and polarized. Anaglyph technology is technically inferior loosing color quality as part of the process.

The polarized 3D glasses which have recently arrived on the market can be either linear or circular polarized. Linear polarized glasses unfortunately rule out lying down or sprawling comfortably while watching TV as one must keep one’s head vertical for the glasses to work. This 3D technology relies one eye seeing a vertically polarized image and the other a horizontally polarized image. While circular polarization obviates the need to keep one’s head vertical it’s unfortunately not used in 3D TV as it requires a special projector and filter.

A prime advantage of passive 3D glasses for the consumer is reduced cost. A significant disadvantage of passive 3D is the loss of resolution with each eye viewing only 540 lines. It is a significant and noticeable step down from 1080p (Full HD).

Active 3D Glasses

Active 3D glasses are the most common type encountered in the 3D HDTV market – most likely due to this being the simplest 3D HDTV technology for manufacturers to implement. Active 3D glasses must be powered as the 3D technology supported creates depth by showing alternate images from a slightly different perspective in sequence to the left and right eye. Ensuring each eye sees slightly different perspective images requires LCD shutters built into the lens in front of each eye synchronized with the frame rate. The LCD shutters are open when the appropriate perspective frame is shown and closed when the opposite is shown. Synchronization is achieved through the use of an infra-red emitter mounted on the television.

Active 3D glasses with the LCD shutters, Infra-red receiver and battery are heavier an less comfortable than passive 3D glasses. They are also significantly more expensive than passive (polarized) ones. As images are not overlayed, 3D technology using active 3D glasses looses no picture information and produces the highest quality experience.

Conclusion – Active vs Passive 3D Glasses

In our opinion the extra cost and lesser comfort of active 3D glasses are outweighed by the superior 3D picture quality produced by this technology. The reduction in image resolution with passive 3D glasses is too significant.