MCG Reports
Human Factors Impact on Near-eye Design
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The United States Display Consortium (USDC) issued a request for proposal for human factors research related to near eye displays in early 2001. In mid September, USDC awarded a contract to McLaughlin Consulting Group (MCG) to pursue their proposal (See Press Release).
The MCG approach is to conduct a range of experiments using knowledgeable observers and custom near eye experimental fixtures to quantify the relationship of several key optical design parameters to display human factors and ergonomics. Results for the experiments will be further corroborated with observation and rating of commercially available displays.
The results of the program will be reported to members of the USDC. For membership information, contact USDC directly.
Participation in Human Factors Experiments.
MCG needs knowledgeable observers to participate in the human factors experiments. Observers will be asked to view a variety electronic images and rate them with regard to readability and attractiveness. The experience will resemble that of an eye examination by an optometrist, but the images will be video, graphic, and text. The trials will be conducted at I-O Displays, Menlo Park, CA starting in January. If you would like to be an observer, please contact MCG at info@mcgweb.com.
Program Objectives
Our objectives are to provide the USDC with clear, simple, and useful design guidelines and rules for the key parameters that impact the performance, comfort, and user friendliness of head mounted and near eye displays. We intend to address the technology void that exists between past research that focused on very specialized HMDs and the near term need for useful design rules for commercial and industrial headsets.
The McLaughlin Consulting Group team combines a unique complement of resources to bridge the gap between past research and commercial needs. First, our program architect and chief technologist, Dr. Kirk Moffitt, is a leading researcher of human factors related issues and head mounted displays and was the editor of the foremost text book on the subject. Second, Charles McLaughlin, is a recognized market and business researcher on microdisplays and personal displays and has published a series of in depth reports analyzing the commercial challenges of developing high volume markets. Third, James Pfeiffer, is a top Silicon Valley product designer who has spent the last five years as CEO of a start up company commercializing a head mounted display.
Based on our research and experience, we will focus our research on only three platforms. We intend to focus on the needs of the communications, computer, and entertainment markets for near eye displays. Based on our assessment of market needs, we propose to concentrate our efforts on moderate FOV binocular displays and both head stabilized and bring to eye monocular information displays. These three categories are likely to capture the lion's share of the near-eye display market in the following segments:
1. Camcorder and digital still camera viewfinders
2. Embedded viewers in smart phones and Internet appliances
3. Peripheral information headset displays for cellphones, PDAs, HPCs
4. Peripheral extended-view headset displays for DVD, TV, laptops, and game consoles
Summary of Experiments
Objective |
Simulation |
Experimental Design/Conditions |
Human Factors Variables |
Define focus/vergence and line of sight parameters |
Binocular optics and pc & video images; two populations with and without bifocals/presbyopes |
All combinations of focus/vergence at 0.5, 1, 2 m + ƒ in combination with LOS of 0, -10, -20 |
3-Way statistical analysis of: |
Define FOV for pc & video imagery |
Binocular SVGA and bring to eye QVGA with both graphic and video images. Follow up evaluation of USDC furnished commercial displays |
22-38° FOV pc & video images for SVGA; 4-10° FOV PDA graphics for QVGA |
FOV x Image interaction x pixel count |
Define eyewear compatibility requirements for a range of eyewear |
Manikin head & assorted eyewear; 3D position device |
Head & eyewear landmarks measured in 3D space |
1. 3D eyewear plots |
Assess several methods of reducing rivalry with monocular HMDs |
Monocular HMD |
Non-HMD eye: |
Viewing comfort |
Interpupilary distance (IPD) |
None |
Survey literature |
Comprehensive IPD database |
Define exit pupil requirements |
Monocular bring to eye handheld viewers |
Exit pupils at 6, 8, 10, 12 & 14 mm |
1. Difficulty with image acquisition |
Define weight & balance tolerance for eyeglass-type and head-mounted displays |
Eyeglass-type and head-mounted frames with incremental weights |
Range of weights and forward offsets centered on 100 g |
Comfort for weights and forward offsets for eyeglass and head-mounted displays |
Brightness and Contrast Ration |
Binocular near eye display with adjustable image brightness and contrast ratio |
Observer will adjust image brightness and contrast ratio for PC and video images for 3 ambient lighting conditions |
Preferred image luminance and contrast ratio based on ambient lighting |
Description of Experiments
Fixed Focus/Vergence and Line of Sight (LOS)
This experiment will provide binocular near-eye display guidelines for setting the fixed image-focus and line-of-sight (LOS). These guidelines will be presented in the context of both computer and video images.
Field of View
This experiment will provide near-eye display guidelines for field-of-view (FOV) for SVGA format computer and video applications. A second study will extend to the smaller QVGA format for cell-phone and PDA applications.
Eyewear compatibility
The use of eyewear has always created problems with HMDs. This experiment will be limited to the problem of eyewear compatibility&emdash;the distance from the eye to the first HMD optical surface and defining what eyewear fits inside of this envelope.
Binocular Rivalry with Monocular HMDs
The most difficult problem for monocular HMDs is binocular rivalry (Moffitt, 1996; Peli, 1990). The HMD image seen by one eye rivals the background image seen by the other eye. The result can be the slow alternation between eyes, or a patchwork made of images from each eye. This rarely occurs in our normal activities because we view most images with both eyes.
Interpupilary Distance (IPD)
Many binocular HMDs provide for the adjustment of each eyepiece/display assembly laterally so as to capture the desired population of Interpupilary distances (IPDs) (Moffitt, 1996). The size of the exit pupil can help capture some of the population, but lateral translation is inevitably required. As an example, a typical exit pupil is 10 mm while the female/male 99th percentile IPD range extends from about 52 to 74 mm. Adding children or adolescents to this population, as well as people from other countries, could extend this range but no data are readily available. Many HMD designers rely on U.S. Military data that are 10 to 30 years old (e.g., Gordon et al, 1989) . We intend to survey a wide range of literatures to construct a database of IPD.
Exit Pupil
This experiment will provide near-eye display guidelines for exit pupil size using monocular bring-to-the-eye devices. The size of the exit pupil is an important discriminator for comparisons with common optical viewers.
Weight and Balance
Early HMDs earned a bad reputation because they were heavy and off-balance (e.g., Kalawsky, 1993). Recent developments in video electronics, miniature displays and LED backlights make lightweight HMDs a reality. Many new designs are styled as oversized eyeglasses. This creates the problem of bearing much of the weight on the bridge of the nose. We intend to conduct an experiment on the relation of comfort to weight for both eyeglass and head-supported HMDs.
We will construct two HMD fixtures that can accept increment values of weight and balance. One will be designed as a pair of oversized glasses, and the other as a more traditional head-supported display. Test subjects will rate the comfort of each weight and balance combination. We expect the average weight/balance tested to be 100 grams and balanced forward.
The results will provide a straightforward recommendation for acceptable comfort levels for both head- and nose-supported HMDs as a function of weight and balance.
Brightness and Contrast Ratio
This experiment will provide near-eye display guidelines for the required brightness and contrast ratio for computer and video imagery in the context of ambient lighting. Given the critical importance of power for head-mounted and portable devices, these data on brightness will prove valuable for developing economical systems.
Program Schedule
The program has four steps.
- Fixture design and approval 4Q01
- Fixture fabrication and observation lab set up and check out 4Q01
- Observation Trials 1Q02
- Analysis, report, presentation 2Q02
Key Personnel
Dr. Kirk Moffitt
Dr. Moffitt is a consultant in La Quinta CA, specializing in human factors design for displays and controls. He holds a Ph.D. in Engineering Psychology, and has 20 years of industry experience. Dr. Moffitt's primary work has been on head-mounted displays. He is the co-editor of the McGraw-Hill text Head Mounted Displays: Designing for the User, and has published over 30 articles and reports. He also holds a patent on a method to reduce rivalry with binocular HMDs. (more...)
Jim Pfeiffer
Mr. Pfeiffer, has more than 30 years' experience in engineering, manufacturing and finance and holds 12 patents for new products and manufacturing processes. Mr. Pfeiffer is currently Principal of Pfeiffer Consulting in Los Gatos, specializing in strategic product and market development activities in the HMD, LCD and human interface product areas.
Charles McLaughlin
Mr. McLaughlin is a consultant with the McLaughlin Consulting Group (MCG) in Menlo Park, CA, specializing in the display industry. He numbers among his clients both Fortune 1000 corporations and start up companies. Drawing on his background as an entrepreneur and new product pioneer, Mr. McLaughlin focuses his personal attention on defining opportunities, developing market strategy, executing sales plans, and mediating financing and partnering relationships. (more...)