CRTs

Most camcorder viewfinders can be removed (e.g. from a broken camcorder, or from a surplus supply) and easily adapted to mount over one eye. It's preferable to mount above the eye, rather than to the side, due to weight balance and, more importantly, the desire to minimize moment of inertia. The sense (whether a clockwise pattern appears clockwise or counterclockwise) of the display can be reversed by reversing the terminals on the deflection (yoke) coil. It is usually preferable to reverse the horizontal terminals rather than the vertical terminals owing to the fact that timing would otherwise get reversed quite severely (making it difficult to switch back and forth if you later decide to use a spinning filter wheel for color). Note, however, that the horizontal circuit operates at higher frequencies and higher voltages are often involved than in the vertical circuits. Thus insulate carefully, and keep leads as short as they were originally.

Good strong safetyglasses or other solid polycarbonate glasses (something that passes the .22 calibre bullet test) are a good idea, to keep all the sharp optics (and pieces of broken glass if the tube implodes) out of your eye. If properly configured, the viewfinder can be made detachable, so it can be snapped in place when in use, and popped off for stowing in a pocket when not in use. In this way, it will not block your field of view while walking around (particularly important for dusting, or other work in low light).

Shields for the high voltage are also a good idea (see the copper mesh I have on WearComp6). The copper mesh shield is grounded and also forms part of the ground plane for the antenna.

Most cheap camcorder CRTs cannot display sharp text in an 80 column display. WearComp2 based on a 6502 processor, had video output with 40 characters per line of text, and only uppercase text. This worked quite well worn on my back with a CRT over one eye, but not with an 80 column card, as the text became too small, resulting in considerable eyestrain. Some better CRTs (like the viewfinders from high-end cameras rather than camcorders) can display 80 column text quite well. My 1980 CRT-based system still displays 80 rows of text quite nicely.

Unfortunately, computers generally no longer output video like the Apple ][ and Amiga computers used to do. Now you need to buy a VGA to NTSC converter. I bought an AI Tech VGA to NTSC converter for $249; it runs on 9 volts, and draws 1/2 amp. More recently there are smaller VGA to NTSC converters, and the power consumption can be reduced considerably. See the WearComp6 howto (wearhow) guide).

If you only need it to work inside X (e.g. don't mind not seeing BIOS and textmode), you can connect directly to TV. This is quite easy to do. There used to be a good summary of it on the WWW, at http://www.sput.dsl.nl/~rob/, but this link doesn't work anymore, (Rob's page on how to connect directly to TV sets, and other useful info) neither does the mirror site, http://www.signature.nl/~rob/, but the essential portions of this info (e.g. specifics of the TV connection) is available here, http://wearcam.org/wearhow/tv-x.html

Of course images display well on CRTs; although the screen is not in color, the tonal range is quite good. In fact, the tonal range of an old CRT taken from the curb on garbage collection day is much nicer than many expensive LCD displays.

Ed Gritz

You can get a really high quality CRT from ED Gritz, Tel. 619 434 4676; Fax: 619 434 7875. This is a business he operates out of his house, distributing high-quality Miyota CRTs. The one that I've been using is the one with the 6kv anode (black and white), $750, and it works very well, especially for making critical tone-scale decisions in image acquisition adjustments, placement of lighting, etc.; the extra voltage gives it much better performance than a camcorder viewfinder.

Consider also a waist-mounted TV

An alternative to HMDs is a belly-mounted TV set, less than $50 new, and works well with appropriate fonts (e.g. XF86Config file or the like). To see how to mount, see a picture of author wearing a waist mounted TV, second from leftmost image. TV was attached to a heavy belt. In the early days, a power inverter was needed, but more recently 12 volt TVs have become readily available. See below for some alternative small VGA sets, or consider also the newer LCD TV sets, such as the $99 Sharp TFT LCD from http://www.eio.com/colorlcd.htm. The Sharp TFT LCD is an amazingly small size TV for its 6 inch diag. display size. It's approx. 6in wide, 4.5in high, 7/8in thich compared to a commercially available 6in TV set which is (for example my SONY 6in TV) 7in wide, 6in high, and 1.5in thick. The small size of the Sharp TFT LCD makes it great for WearComp, shared display, etc., or worn around neck so others can see the output. It requires backlight power supply (inverter) obtainable from Jameco (800) 831-4242, part number 142252. Product No. FPWR1. Watch this site for future additions on new applications of this small size Sharp TFT LCD.

M1, Liquid Image Corporation

A nice sleek, slender, and readily available HMD is the M1 made in Canada, by liquidimage. The unit takes NTSC or VGA, and automatically selects between NTSC and VGA depending on which is connected. Power consumption is reasonable, although it's CPLD-based (e.g. a little more power consumption than an ASIC-based system). It's 240 down by 320 across pixels: not full VGA resolution, but good enough for 40x15 size text window to clearly read text (and slightly higher amounts of text if you don't mind some eyestrain).

Liquid Image Corp has been very helpful in terms of providing information, and in terms of custom work on small numbers of these units.

Liquid Image Corporation
(204) 988-3003
(204) 988-3000
(204) 988-3050 Fax
liquid@liquidimage.ca
http://www.liquidimage.ca/

skyex/albatech

The skyex/albatech "personal monitor", Personal Color Monitor US$ 1490, is a high quality wearable video display. An ingenious beamsplitter design routes the image from a single display medium into both eyes, so that it can be used for many hours with minimal eyestrain. Although one eye output is slightly brigher than the other (due to the designs needed to make it so ultra compact) one very quickly adapts to this difference, and what is perceived is a very clear television picture. Despite the small size of the unit, it has many adjustments so that it can be adjusted for comfortable viewing without too many of the compromises that lead to eyestrain in fixed (non-adjustable) units.

Although there is no means to input separate images to each eye, the device is outstanding in applications where there is a single (mono, as in non-stereo, not to be confused with monochrome which the unit is definitely not) video signal.

Color rendition is really good. Text is not as sharp as on a CRT or other high resolution device, but the color fidelity is such that pictures of natural scenes look quite good.

Because of its light weight, the apparatus is also very comfortable to wear for many hours. It is built into eyeglasses rather than a helmet type design, and this makes it more natural to wear, and also more acceptable to those who don't want to "mess up their hair".

See a mirrored copy of their main www page.

Colorado :
20361 W. Thunder Rd
Colorado Springs, Colorado 80908
USA
Tel : (719) 495-3254
Fax : (719) 495-8508
E-Mail : klugex@pcisys.net 

Florida :
1408 Sw 13th Court
Pompano Beach, Florida 33069
USA
Tel : (954) 941-8066
Fax : (954) 941-3426
E-Mail : albatech@skyex.com 
http://www.skyex.com/albatech/

Timeline

They have one small size CRT (1 inch) and also some smallish monitors (5 inch) which are a bit large for a wearable, but small enough to haul along to review previously recorded video, etc. If anyone buys one of the 5in displays, please let me know how well it works... How well do TTL or CGA work on std VGA?
1.0in CRT: resolution 250*300, 6kV; complete composite viewfinder.
(this from miyota... buy and sell closeouts, only 70 units got; now down to 50)
THE 1 INCH CRT IS NOW SOLD OUT!!!   :-(

5" Amber or B&W $25.00

5" Color Monitor $39.00 or 2 for $69.00 
              Flat faceplate 
              320 x 200 dot resolution 
              CGA & Hercules Compatible 
              12VDC Operation 
              15.75 KHz Horizontal Frequency 
              60 Hz Vertical Sync. Frequency 
              Open Frame Construction 
              Standard Interface Connector 
              Degaussing Coil Included 
              Mfr. Samtron 

http://www.digisys.net/timeline/blowout.html#monitor

Private Eye

Using a row of red LEDs and a vibrating mirror, the Private Eye produces a razor-sharp binary display. The Private Eye isn't much good for image display but text is amazingly clear. I find the color (red) to bother me, but many people are not bothered by this and find the private eye quite comfortable to view for extended time periods. Despite its shortcomings, it has the tightest point spread function of any of the displays I've tried, and the best contrast as well. The private eye is also very robust (e.g. can withstand a great deal of physical shock) and can easily be made waterproof for all-weather use.
The following info is now obsolete (Private Eye no longer in mass production)
Phoenix group, phone=516-349-1919; fax=516-349-1926
$1500 for 280down, 720across, with driver board
approx. $4000 768down, 1280across (not available yet)
will make higher-resolution displays on request.

cybermaxx

VR4

Here are my "magic glasses" (the hardware on which "VisualFilter" runs) implemented with a VR4 display (to which I've attached cameras and communications antenna).

The VR4 is a high-quality RS-170 color video display, made by Virtual Research, virtualres@aol.com. http://www.virtualresearch.com/products.html

Having worn it for extended periods of time, over a 2 week period, I found it to be quite comfortable. The display quality is quite high, close to that of a good television monitor (e.g. almost as good as a color CRT). Adjustment knobs for head size make it very easy to have someone else quickly try it on. Two separate inputs are provided, one for each eye, and there is a stereo/mono switch which makes it easy to quickly test a single video input, feeding it to both eyes. There is a buffered monitor output on the left channel to plug into an external TV set or the like. The input can be either component (YC) or RGB RS-170 video.

The supply voltage is 16 volts. The VR4 comes with a lightweight, high-efficiency switching power supply for operation from 120 volts AC. I found it to work quite well from one of my wearable AC outlets, though it is also quite easy to build a DC to DC converter from 12 volts to 16 volts so that it can be run from a standard 12 volt battery.

The VR4 is probably one of the best choices for color RS-170 video display, but is not quite sharp enough for display of small fonts on a computer screen.

VR5

To be available September 1995:
Model:  VR5
Display:  Dual 1" CRTs with color shutters
FOV:  53x at 100% overlap; 72x at 50% overlap
Resolution:  SVGA or better
Input:  Field Sequential (RS-170)
Weight:  Under 2 lbs.
IPD: Adjustable 52mm - 74mm
Eye relief:  Adjustable, users may wear glasses
Available:  September '95
Price Point:  Under $20,000
Virtual Research Systems, Inc.  V6 US$ 7.900, V8 US$ 13.500
2326 Walsh Avenue
Santa Clara, California 95051
Tel: (408) 748-8712
Fax: (408) 748-8714
E-mail: info@virtualresearch.com        

Kopin

If you are willing to give up color, and stereo, the Kopin display is very good for crisp clear display of small fonts. It does quite well with combined text and greyscale image display. The Kopin display is used in the ``Personal Assistant'', made by CPSI:

However, using the Personal Assistant for an extended period of time, I find that the green display is a little annoying -- after taking the Personal Assistant off, I can read 3-D comics without 3-D glasses. This is because my display eye sees everything with a magenta cast (after having been stimulated by green), while the other eye sees normally (which even looks a little green by comparison).

Possible work-around: change backlighting to white, although the lcd only works with monochromatic sources (need an lcd that works with broadband sources).

I also found the Personal Assistant display slides down my face, and I have to keep pushing it back up every couple of minutes, unless I set the tension high (but that causes it to be uncomfortable due to the pressure on my head).

Work-around: additional supports around the top of the head to prevent it from sliding down.

Result with both these work-arounds: a very comfortable display with good clear crisp text and greyscale image display capability.

Virtual Vision

Perhaps the nicest-looking, or at least the most natural-looking glasses are those made by ``Virtual Vision''. These are wrap-around sunglasses (resembling ski-goggles) with built-in color television, introduced April 1993.

I find these ``cool shades'' are comfortable to wear for many hours at a time, and provide a convenient display for video:

There are even miniature earphones that can be stowed on the sides when not in use. While the image is not razor sharp (so they're not too good for displaying text), the small size, comfortable design, and ``normal'' appearance makes them quite useful for image display. They are neither intended, nor marketed for virtual reality, but, rather, are meant for image display (e.g. for use as a camera viewfinder).

They are available in either the left-eyed version or the right-eyed version (you need to specify at time of purchase because they cannot easily be reversed.

The operating voltage is 6, and they come with battery and charger. The company wisely used a standard battery type (exactly like those used on a Sony HandyCam) rather than introducing yet another battery type. Thus if you already own a Sony HandyCam, your battery management will be simplified.

My time wearing the Virtual Vision totals hundreds of hours, and they have been very reliable. The only small flaw is the connector from the eyewear to the control box, which you may want to strain-relief by attaching a small metal support with hot-melt glue and wrapping to the plug with gaffer's tape. Otherwise, the wires may weaken over a year or two of heavy use, and break off inside the plug. Of course, new cables are available (changing the cable is quite easy with a phillips screwdriver to open up the eyewear), but a simple strain-relief will eliminate the need to keep spare cables around.

There are 3 different visors available, dark, medium, and light.

Virtual vision refers to their product as an ``augmented reality'' system, because you see through the glasses and augment the real world with what appears to be a very large television set quite far away. The focus is adjustable so that eyestrain can be minimized, and I've found that there is sufficient range of adjustment that people who have relatively strong prescription glasses can see Virtual Vision without their glasses.

Virtual Vision also comes with a tuner module which may be removed when not in use. The tuner facilitates reception of standard broadcast television, or use with a downconverter to receive amateur television (ATV). Its external antenna jack makes it easy to plug in an ATV downconverter. Alternatively, if you're not squeamish regarding the sight of bare components, you might want open it up and modify it to receive ATV directly. Using Virtual Vision with ATV is a nice way to stay in touch with a partner -- seeing eye to eye. The sound quality of the Virtual Vision is excellent; it has two very small earphones that can be disconnected if desired, or they can also be stowed out of the way (in small holders moulded into the eyewear) but remain connected when not in use when rapid deployment capability is desired. The sound comes in the standard audio subcarrier of the received signal in RF mode (just like a normal TV set).
There is an antenna jack in the tuner. When you plug video into the external video input jack, the video automatically switches from RF to baseband. Likewise with the sound. You can switch the sound and video independently from baseband to RF. For example, you can plug in an external baseband video input (e.g. camera) and listen to the RF (e.g. broadcast television) sound at the same time by having nothing plugged into the audio jacks.

Virtual Vision, Inc.
7659 178th Place N.E.
Redmond, Washington, 98052
tel: 206 882 7878
fax: 206 882 7373
(I also observe that 1800 619 4680 can get there)

Cost is under $1000 (e.g. list is around $900; should be able to get it for around $700).

Virtual Vision sold the rights to the Virtual Vision Sport Glasses to the following company:

http://www.vetco-inc.com
VETCO Electronics
        13029 Northup Way               7866 Southwest Nimbus Ave
        Bellevue, WA 98005              Beaverton, OR 97008
        Phone (425) 869-7025            Phone (503) 574-2299
        Fax (425) 881-5064              FAX (503) 469-0520
        E-Mail: vetco@vetco-inc.com     E-Mail: vetc0@gte.net
See also, http://www.virtualvision.com/

Virtual vision has evolved into Virtual Image Dislays Inc and Seattle Sight Systems. The new system described in http://www.seattlesight.com/sss.html is quite innovative. Seattle Sight Systems, Inc. , starts at US$ 3500

http://www.seattlesight.com/gpseries.html
14150 N.E. 20th Street., #313; Bellevue, WA 98007
Telephone: (425) 643-1966; Fax: (425) 643-9976
General inquiries may be directed to: ssightsys@aol.com

See also, a picture of Virtual Vision's new VCAP.

PT-01


The PT-01 is comfortable as-is (e.g. I didn't find I needed to modify it or add any extra padding to wear it for long periods of time).

The PT-01 is very similar to the Virtual Vision (it even has the same style of connector, so if you already have a Virtual Vision, you can plug the PT-01 directly into the Virtual Vision belt pack, which means that you can use the PT-01 as a tuner with the Virtual Vision belt pack).

The PT-01 has the same high-quality color rendition as the Virtual Vision display. Basically the PT-01 is a high-quality NTSC monitor, with sufficient quality of color rendition to facilitate its use in adjusting the color balance of cameras, etc. The spatial resolution is not quite high enough to read 24 rows of 80 column text.

The PT-01 delivers the identical NTSC input to both eyes, so that eyestrain is reduced during long viewing periods, and the PT-01 also fills a greater angle than the Virtual Vision, but you can't see through the PT-01, so it may be less or more preferable than a Virtual Vision depending on your application and preferences. Basically I use the Virtual Vision when I want to monitor a signal while walking around (e.g. for testing video transmitters by walking around and looking at the signal quality), but the PT-01 when I want to concentrate more on the video signal and less on the surroundings. This finding appears consistent with the manufacturers' intent, because the PT-01 requires a wall-socket (e.g. comes with a 7.5 volt wall adapter but no battery) while the Virtual Vision is battery powered. Of course it is a simple matter of obtaining a 7.5 volt battery or running the PT-01 from the VirtualVision belt pack to liberate it from being tethered to the AC. However, care should be used -- perhaps it is just as well it is tethered because of the obvious danger of walking around with your eyes covered up (unless you're using it for a `reality mediator' as I often do).

The PT-01 swings up out of the way, and you can still see the screen when it is pulled out and swung up out of the way.

The sound quality of the PT-01 is superb, and it has standard RCA inputs for stereo sound (3 RCA jacks, 1 for video, 2 for sound). There is also a BNC connector for video input which often comes in handy. Having both BNC and RCA inputs for the video was a wise design decision, and the rugged metal construction of the belt pack is consistent with the high quality that is typical of equipment that has BNC connectors on it, as opposed to the lower quality "consumer grade" equipment that typically only has RCA connectors.

If you're serious about video in the field, you probably want to get both a Virtual Vision and a PT-01 so you can adapt to any situation you might encounter. Both of these units together can be packed into a carrying case that is smaller than most color monitors, and definitely much less weight to haul around.

Look at a diagram of how this display is used.

PT-01 email: Optix1@aol.com http://www.optics1.com/HMD.htm

01 Products, Inc. 3050 Hillcrest Drive Suite 100 Westlake Village, CA 800-538-3008 805.446.1453 FAX:1+ 805.373.8966 A division of Optics 1, Incorporated 3050 Hillcrest Drive, Suite 100 Westlake Village, CA 91362 Phone: 805/446-1453 (800-538-3008) Fax: 805/373-8966 e-mail: hmd@optics1.com

Virtual I/O i.glasses

NTSC version approx. $500; VGA version approx. $700: the difference between the two is that the VGA version comes with a VGA to NTSC converter. However, the VGA to NTSC converter does no better than, say, the $139 AI-Tech converter, so it makes sense to buy the NTSC version and just use another scan converter. Text is readable in 40 characters per row, but it is still different to tell difference between certain characters such as 8 and 0, and some run together such as ``m''; just a blur across. The display is quite comfortable to wear, and forms the basis of a good starting point to then build around (e.g. using better display technology into the i.glasses frame).
1370 Willow Road Suite 101; Menlo Park, CA 94025-1515
PHONE: 1-800-339-5287 650-323-8407; FAX: 650-323-1742
E-Mail: info@i-glasses.com; http://www.i-glasses.com (was http://www.vio.com)

Olympus Eye-Trek

Recently, there was a review of the Olympus Eye-Trek: http://wearables.about.com/library/weekly/aa031201a.htm

Some other more recent products

An up-to-date listing of many modern head mounted displays appears in http://wearables.about.com/cs/displays/index.htm
return to personal imaging, WearComp...


other head mounted display pages/resources:

other resources... from emo@ai (with stereo color lcd interleaved pixels...)
http://www.imaginative.com/VResources/
http://www.imaginative.com/VResources/vr_hardw/vr_hardw.html
http://www.cms.dmu.ac.uk/~cph/VRbib.html
http://vr-atlantis.com/vr_systems_guide/vr_systems_list2.html

Contact info:
Prof. Steve Mann
University of Toronto
Department of Electrical Engineering
10 King's College Road, Room 2001
Toronto, Ontario,
Canada,
M5S 3G4

416.946-3387
mann@eecg.toronto.edu
http://www.eecg.toronto.edu/~mann
Related info: http://genesis.eecg.toronto.edu/wearpubs.html