HMD Head Mounted Display Technology & How It Works
The following article is an in-depth look at what head mounted displays. It discusses what they are, how they work, and their benefits to users. It also includes details on some HMD models which have already been released to the market as well as some details regarding their potential future applications.
What Are Head Mounted Displays?
Head mounted displays, abbreviated as HMDs, provide users with a visual output via a device worn on the head. HMDs typically take the form of goggles, glasses or visors, and are sometimes mounted on a helmet for ease of use. Applications for head mounted displays range from gaming, to military and medical fields.
How Do Head Mounted Displays Work?
Most head mounted displays have a small screen positioned in front of each of the end user’s eyes. Some, however, only have a tiny monitor for one eye, called a monocular HMD. The majority of HMDs are binocular, with displays for both eyes. The advantage of having binocular HMDs is the user is able to perceive depth when both eyes are able to view their own small screen. Three dimensional perception is achieved with binocular HMDs either with dual video displays, or with multiplexing.
The monitors in HMDs can employ various different display technologies. The earliest HMDs utilized Cathode Ray Tubes (CRTs). They were heavy to wear and bulky to use. More recent models have Liquid Crystal Displays (LCDs), Liquid Crystal on Silicon (LCoS) or Organic Light Emitting Diods (OLEDs). LCDs, LCoS and OLEDs are more compact and allow for a lighter-weight head mounted display. Their energy use is more efficient and therefore less expensive than those which use CRTs.
Many HMDs, particularly those marketed for gamers, are designed to only display computer generated images (CGI). HMDs used for applications in law enforcement, military, and medicine, for example, have the ability to display a real-world view superimposed with CGI. This is sometimes referred to as mixed reality, or augmented reality. HMDs which only show CGI are considered to be displaying virtual reality.
Many HMDs include speakers or headphones, to enhance the users’ sense of immersion by offering both auditory as well as visual experiences. Latency issues with wireless communications demand that the majority of HMDs be hard-wired to ensure top performance.
What Can You Do With A HMD?
Head mounted displays help to give the user a sense of immersion in the environment they are interacting with, whether that’s completely virtual or real with the added visual enhancements. HMDs also allow the advantage of a hands-free method of sharing information.
The most obvious application for HMD use is for simulation and training. By producing virtual environments end-users can feel immersed in, costs and risks associated with training are significantly reduced. With applications such as flying, driving, parachuting, machine maintenance, surgery, etc., experts can easily and inexpensively sharpen their skills or learn new ones with minimal risks to others and themselves.
Gaming and entertainment are also a popular uses for HMDs. However, there is significant overlap between military training and first-person shooter games, for example. HMD users may be entertained and trained at the same time.
Released HMD Models
Sony’s recently announced HMZ-T1 model contains two 0.7 inch OLED display monitors to produce a 720p 3D picture. The headphones built into this HMD have 5.1 channel surround sound capabilities.
iGlasses offers several different high-end models for computing simulation and gaming. They utilize LCDs, and various models include those for PC and MAC displays. iGlasses includes personal 3D HMDs both at a high-end and consumer price point, each of which also use LCDs in their monitors.
At a much more economical price-point, iTheater’s Head Mounted Display glasses contain two LCDs with a QVGA screen resolution of 320 x 240. The glasses can be plugged into an iPod, and display an image that is the equivalent of watching a 50 inch screen at a distance of 8.5 feet away. The iTheater HR model, by contrast, offers a VGA display of 640 x 480, which is similar to watching a 70 inch screen at that same distance.
Eye-Top Centra’s monocular HMD is essentially a pair of sunglasses with a monitor attached to only on the right eye. The design is sleek and stylish, and the video can be connected via a simple female RCA jack. But it does not aim to totally immerse the viewer in the video. The left eye is free to view the real-world environment.
The Z800 3D visor by eMargin, in contrast, comes with advanced head-tracking to put the user into the 360 degree virtual gaming environment. The displays can be 2D or 3D, and they show a view equivalent to that of a 105 inch big screen.
The Future Of Head Mounted Displays
As with all technologies, the future promises HMDs will become smaller, and less expensive. The marketplace will demand higher resolution, more efficient use of power, faster performance. Though it remains to be seen how much the mainstream will adopt the technology. Governments and corporations will continue to fund research for specific applications of HMDs to benefit their training objectives. However, for the average consumer, the advantages of HMDs may not outweigh the cost.
Although HMDs have been around since the 1990s, they have not been very successful commercially. Corporate and military applications have driven the technology, which may not allow such an easy-fit into the marketplace. For serious gamers, and those training in high-risk fields such as law enforcement, the military, medicine and surgery, head mounted displays are key tools to enhance skills, increase response time and lower costs.
Copyright 3DTVGuide.org 2011
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Comprehensive Guide To 3D TV - 3D HMD Head Mounted Displays
Ready For A Close Up: The Sony Hmz-T1
It is now possible to watch a movie literally anywhere. The Sony HMZ-T1 now solves the only remaining issue: getting a true movie-quality experience in the comfort of your own home.
Making its debut in January at CES, the HMZ-T1 will be introduced for sale in Japan in November 2011. It has undergone some cosmetic changes, but the innovative technology behind the device is still cutting-edge. A Head Mounted Display is the perfect medium to enjoy a movie-theater experience at home.
The entire unit consists of the HMD helmet and a separate processor with HDMI input/output. Simply connect the processor to an HDTV, Blu-ray player, or game console, and then attach the HMD to the processor. Then sit back and enjoy.
The HMZ-T1 takes advantage of OLED technology. Two 0.7” OLED screens with a resolution of up to 1280x720 pixels give the viewer the experience of sitting in front of a 750” HDTV at a distance of 20 meters. This promises near movie-theater quality visual effects.
Using the “Dual-Panel Effect”, the display allows the viewer to HD in a natural-feeling 3D effect. The innovative optical lens design delivers a 45-degree viewing angle without distortion.
OLED technology is also fast. With a response time of 0.01ms, video runs seamlessly through each explosion or car chase.
What’s a good movie without sound? In addition to a fantastic visual experience, the HMZ-T1 takes advantage of Sony’s expertise in the technology to deliver sound. Independent left and right speakers deliver 5.1ch virtual surround sound. Four sound modes allow the viewer to customize the experience to suit his or her taste.
Easy-to-use controls allow the wearer to control every aspect of the viewing experience. The control can control the basic functions of any HDMI CEC compatible device. The headset also has a sensor that shuts it off if it is not being worn; to conserve power further, if left off for a time the unit automatically goes into standby-mode.
The processor unit features dual-input, allowing the device to be connected along with an HD TV. The viewer has the choice of either watching on the HMD, or on the TV screen.
A quick safety note: it is suggested that children under 15 years of age should not use the device. Like any other product that reduces outside stimulus, the viewer should use caution when wearing the HMD helmet. And because of that immersion experience, wearing the device in any situation that may induce motion sickness (such as in a moving car) is not recommended.
When the HMZ-T1 goes on sale in November, the price is expected to be around 60,000 yen, or about $780. This is a small price to pay for the best visual experience on the market.