DIGITAL DEVICES
As was mentioned earlier, differing digital devices lead to differing flexibility in their ergonomic use.
Desktop Computer- The greatest limitations are those that are found in the desktop computer. As stated before, it does allow for the largest amount of “real estate” and allows for multi-tasking more than other digital devices. However it is most restrictive when it comes to ergonomics. Again, when the user wishes to change their posture the person is the one that has to move. While there is some variability in the system as to screen distance and keyboard distance, these are limited by the size and weight of the device. It should be noted that the eyes strain more in focusing and aiming the higher the regarded object. In other words, the higher the screen the more strain on the eyes. So, as a general rule, ergonomically, when an individual is working on a desktop computer the top of the monitor should be at eye level. That is, when viewing the screen (and this is really true of all digital devices) the eyes should be looking slightly downward. I am not saying that the head should be lowered, that should remain horizontal. It is the eyes that should be moved, not the body. This will result in the least amount of effort to focus and aim the eyes.
Regarding the distance to the screen, the minimum distance should be about palm to fingertip distance from the outstretched arm. Further is fine, as long as the screen objects and letters are clearly visible. If not, there will be a tendency to lean into the screen, changing both the distance and the angle in which the eyes regard the screen.
Laptop Computer- The next step up from the desktop computer is the laptop computer. While the laptop certainly increases positioning versatility, it still has limitations. When placed on an appropriate desk or table, the user must look downward at the screen. As noted above, this is a desired position. However, when used while reclining this positioning becomes more difficult. Also, since, the keyboard is usually attached to the screen, the ability to vary the distance to the screen is, likewise, more difficult. As with most other digital devices which are portable, there is difficulty in controlling the lighting and sources of glare. But, given the fact that laptops are portable it’s angle to windows and lighting can be changed, this is a good alternative to the capabilities of a desktop computer.
Tablets- Tablets are next on our list. While certainly tablets are not intended to act as true business computers, their versatility increases their attractiveness. However, glare from the tablet screen is a problem. If you’ve ever tried working on one outside, or at the beach, you will know what I mean. The highly reflective front surface is the problem. So one must angle the screen or find a shady spot in order to view the screen properly. Again, portability is the attraction. It can be used in any location, inside or out and is easily transported. However, with the advent of new thinner tablet-computers, such as the Surface, their sales have diminished.
Cell phones- Cell phones are the height of versatility. Their small size allows for communication, office and personal productivity and you can even make a phone call on it! The problem here is size and the drawbacks of its own versatility. With a small screen, as compared to other digital devices, the reading of documents, email and texts becomes more cumbersome. So the alternative is to either increase the font, resulting in less words per screen, or holding the device closer to make the object larger. However, this last solution results in greater focusing and aiming strain on the eyes. In addition, there is a tendency to hold the cell phone closer to the eyes the more one is reclined. So while a conventional reading distance may be used when sitting upright or standing up, using the device while laying on the couch or in bed results in a closer focusing distance. As mentioned previously: Simply make a fist with one hand and place it on your chin. Then extend your elbow out. This is about the proper minimum distance to hold both cell phones and tablets. While certainly not exact, it provides you with a constant feedback (since your arm is attached to you!) as to the proper working distance. Again, the closer you have the digital device to your eyes, the harder it is to keep and maintain focusing.