3D Glasses – Passive Polarized vs Active Shutter

If you have a 3D TV you need to use the right glasses

3D Glasses Example (Active Shutter Type)
Robert Silva

Although 3D TV viewing has fallen out of favor, there is still a small-but-loyal fan base, with millions of sets in use around the World. 3D viewing is still available on many video projectors, and, there is a slow, but steady flow of 3D movie titles available on Blu-ray Disc.

However, what 3D TVs and video projectors have in common is you need special glasses to view the 3D effect.

What 3D TVs and Glasses Do

3D TVs and Video Projectors accept an incoming 3D signal that is encoded by the content provider, in one of several formats.

The TV or projector has a decoder that translates the 3D encoding and displays the left and right eye information on the TV or projection screen as two overlapping images that look slightly out of focus.

One image is intended to be seen by the left eye, while the other is intended to be seen by the right eye. The viewer must wear glasses designed to receive the left and right images and pass them to the left and right eye.

After received by the eyes, the image signals are sent to the brain. The brain combines the two overlapping images into a single 3D image.

Types of 3D Glasses

Passive Polarized Glasses

These glasses look and wear like sunglasses. They require no power and can usually be placed over existing eyeglasses if needed. Passive glasses are inexpensive to manufacture and range from $5 to $25 for each pair depending on the frame style (rigid vs flexible, plastic vs metal).

What We Like

  • Passive glasses are lightweight.

  • The glasses are inexpensive, about one third, to one-quarter the price of Active Shutter glasses.

  • No flickering. This means less discomfort and eye fatigue over long viewing periods.

  • No power required.

What We Don't Like

  • The 3D image is one-half the resolution of a 2D image displayed on the same TV due to both left and right eye images being displayed at the same time.

  • The presence of horizontal lines on the screen and some jaggies artifacts on the edges of objects may be noticeable, mostly with text and straight line geometric shapes.

Active Shutter Glasses

These glasses are slightly bulkier than passive glasses since they have batteries (some use watch batteries, others use rechargeable batteries), on/off button, and a transmitter that syncs the rapidly moving shutters for each eye with the onscreen display rate. These type of glasses are more expensive than passive polarized glasses, ranging from $50 to $150 depending on the manufacturer.

What We Like

  • The 3D image resolution is the same as the 2D image displayed on the same TV as a result of left and right eye images being displayed sequentially, in synch with TV/projector's screen refresh rate and the opening/closing of the LCD shutters in the glasses.

What We Don't Like

  • Flickering due to rapid opening and closing of the LCD shutters may be detectable by some viewers, causing discomfort.

  • Sometimes bulkier than Passive Glasses.

  • Battery power required.

  • Expensive, usually, two or three times the price of Passive Polarized Glasses.

There has been a debate on which system actually delivers the best result for the consumer. Findings from TV and 3D viewing experts Joe Kane and Dr. Raymond Soneira provide some insight.

The Glasses Have to Match the TV or Video Projector

The brand or model 3D TV/video projector determines which type of glasses need to be used.

When 3D TV was introduced, Mitsubishi, Panasonic, Samsung, and Sharp adopted Active Shutter glasses route for LCD, Plasma, and DLP TVs (Plasma and DLP TVs have been discontinued), while LG and Vizio adopted Passive Glasses for LCD TVs. Also, although Toshiba and Vizio mostly used passive glasses, some of their LCD TVs did use Active Shutter Glasses. To make things more confusing, Sony used mostly the Active system but offered some TVs that used Passive.

  • Due to the way Plasma TVs display images, they only work with Active Shutter glasses. However, both Active Shutter and Passive Glasses can be used with LCD and OLED TVs – the choice was up to the manufacturer.
  • Consumer 3D video projectors require Active Shutter 3D glasses, which allows use with any type of screen or flat white wall.

Although 3D TV production has ended, 3D glasses are still available, but prices vary.

Another factor to consider is that active shutter glasses used for one brand of TV or video projector, may not work with a 3D-TV or video projector from another brand. This means if you have a Samsung 3D-TV, your Samsung 3D glasses will not work with Panasonic's 3D-TVs. So, if neighbors have different brand 3D-TVs, in most cases, they will not be able to borrow each other's 3D glasses.

3D Without Glasses Is Possible but Not Common

There are technologies that enable 3D viewing on a special type of TV or video display without glasses. These are referred to as "AutoStereoscopic Displays".