3D LCD Shutter Glasses are glasses used in conjunction with a display screen to create the illusion of a three dimensional image, an example of stereoscopy. Glass containing liquid crystal and a polarizing filter has the property that it becomes dark when voltage is applied, but otherwise is transparent. The glasses are controlled by an IR, RF, DLP-Link or Bluetooth transmitter that sends timing signal. The glasses alternately darken over one eye, and then the other, in synchronization with the refresh rate of the screen, while the display alternately displays different perspectives for each eye, using a technique called Alternate-frame sequencing.
Advantages of LCD Shutter Glasses
- LCD shutter glasses mostly eliminate "ghosting" which is a problem with other 3D display technologies such as RealD 3D, or Dual projector setups.
- LCD shutter glasses are available for around $100, not counting the cost of the required display.
Disadvantages of LCD Shutter Glasses
- Flicker can be noticeable except at very high refresh rates, as each eye is effectively receiving only half of the monitor's actual refresh rate. Modern LCD glasses however generally work in higher refresh rates and mostly eliminate this problem.
- Until recently, the method only worked with CRT monitors; some modern flat-panel monitors now support high-enough refresh rates to work with some LCD shutter systems
- Because the LCD shutter glasses are shutting out light half of the time, and are slightly dark even when letting light through, less light reaches the viewer's eyes from the display. This gives an effect similar to watching TV with sunglasses on, i.e. a much darker picture. However, this effect can produce a higher perceived display contrast when paired with LCD displays because of the reduction in backlight bleed.
- Frame rate has to be double that of an ordinary stream to get an equivalent result. All equipment in the chain has to be able to process frames at double rate; in essence this doubles the hardware requirements of the equipment. This is specially noticeable when the image stream is interactively generated in real time by 3D hardware on computers.
There are many sources of low-cost/low quality 3D glasses. IO glasses are the most common glasses in this category. XpanD 3D is a manufacturer of shutter glasses, with over 1000 cinemas currently using XpanD glasses. With the release of this technology to the home-viewer market as of 2009, many other manufacturers are now developing their own LC shutter glasses, such as Panasonic and nVidia (GeForce 3D Vision kit). The GeForce 3D Vision kit comes with 3d shutter glasses, a transmitter, and special software and graphics drivers. A 120hz monitor is required to use the GeForce 3d Vision, however, which limits the current market; nearly all flat panel monitors run at 60 hz.