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Three basic parameters for reading:
1. READING SPEED
Is individual and varies a great deal. Limited by field of vision and also by the degree of magnification, contrast, light and colour composition. A reader without any visual impairment normally reads between 250-300 words per minute. A person with impaired vision normally reads between 30-100 words per minute. Over 100 words per minute is considered to be fast reading. To achieve the optimum reading speed, the system controls must be easy to reach and easy to adjust. Automatic focusing is particularly important.
2. UNDERSTANDING OF WHAT IS READ
Understanding what you read may sound obvious. Everybody who reads a page or a chapter of a book, however, is well aware that sometimes you have to re-read a section when concentration wanes for a moment. When a user sits in front of a monitor screen and at the same time as reading, must operate the camera, many other factors come into play that disturb concentration (movements, changes of position, etc.). The camera system must therefore be easy to operate.
3. READING ENDURANCE – WEARINESS
All experienced readers know how tiring it can be to lie and read a thick book, compared to sitting comfortably and having good support. The mere fact of sitting in front of a monitor screen makes reading hard work and affects the reader’s endurance. Sitting incorrectly, for example, with the eyes directed upwards, is often completely devastating for the user. A good system must therefore be designed following correct ergonomic principles.
CRITERIA FOR TESTING – Other important points to take into consideration
A. Comfortable and good sitting position
B. Monitor at the right height
C. Optical correction
D. The position of the camera. Working area and writing position
E. The reading table should ALWAYS be fully extended when adjusting magnification, brightness and contrast
F. Is an XY table needed?
FINDING OPTIMUM PARAMETERS
1. Lineal magnification. A “technical” measurement, amongst other things, for purposes of comparison. How is lineal magnification measured? (Effective magnification. The actual magnification experienced on the retina. From the user’s perspective, the most important.)
2. Reading distance. Most of us have our own “distance” to achieve a clear picture on the retina. N.B. It is important to maintain a constant distance to the monitor screen.
3. Brightness/light level. Go through the brightness scale and adjust to individual preference/requirement.
4. Contrast level. Go through the contrast scale and adjust to individual preference/requirement.
5. Positive or negative image. Test.
DETERMINING FACTORS – That have a direct effect on the user in terms of distance between the eyes and the monitor screen
A. Degree of magnification. 20x magnification at 30 cm becomes 10x at 60 cm.
B. Light/brightness. Moving backwards away from the screen from 30 cm to 60 cm entails a fourfold reduction in light strength. Light and acuteness of vision have a clear correlation.
C. Radiation. A user 15 cm away from the screen is exposed to 4 times stronger radiation than one who is 60 cm away from the screen. "The radiation” referred to are electromagnetic fields and static electrical fields. (See the section regarding important connections).
The camera system has what is known as projecting magnification – magnification takes place via the optical (or digital) zoom. To look at photographs or objects it is important to start with a low level of magnification. For example, the fact that it is possible to zoom 30x is completely meaningless and unusable when looking at an A6 photograph. Then greater magnification IS NOT important, quite the contrary – an overview starting at 1.3x for example.
When the user is in the right position in front of the monitor screen, with the right degree of magnification, the right brightness and contrast and otherwise a comfortable reading/working position, all movements, stretching, searching for controls, etc., negatively affect both reading speed and understanding and not least of all, mean that endurance decreases.
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IDEA-SCX
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SynSupport Sverige AB
Illervägen 15
SE-352 45 Växjö
Tel. +46 470-72 98 88
Fax. +46 470-74 95 80
E-mail. info@synsupport.com
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SONY partner
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