Recently we bought a 7" tablet computer to see if it can be used to read books。 From the point of view of usability this solution is quite good, with the right software installed in the tablet you can read and browse all kind of files, fit the image of the page to the screen, scroll pages quickly etc。。。。
Unfortunately however there is still the problem of electromagnetic radiation from these electronic devices. The EM radiation comes from various components, some components may be disabled but other cannot. For this reason, the tablet computer is a very dangerous health hazard.
All tablet computers today have a touchscreen. The touchscreen is a quicker way to give commands to the tablet, and it allows also new kinds of commands with two or more simultaneous touch points. However the electric field of the touchscreen can damage the user's finger. I have tried several tablets of different sizes and different brands, both of the well known brands and of the minor unknown brands. Some models hurt my finger really too much. Last time I tried a 10" tablet in a shop, I used the touchscreen with my index finger for a few minutes, and I started to feel a strange pain in my finger. I recognized the pain caused by an electric field, maybe of high frequency. But the pain stayed for about one hour after I stopped using the touchscreen and left the shop. Then I tried three different models of 7" touchscreens, using them for about 15 minutes, and these touchscreens didn't hurt my finger. In all cases the touchscreen of the tablet was of capacitive type, which is the most common in latest tablets. I suppose that larger capacitive type touchscreens create a stronger electric field on the surface, because the distance of the screen points from the contacts around the edges is greater and so a stronger field is needed. Instead, smaller screens have probably an electric field of a lower intensity. Anyway, just the touchscreen electric field problem would have turned me away from the tablet computer, but the 7" didn't hurt my fingers so I decided to buy one.
All models of tablets currently have an embedded WiFi device, which is used to create a connection with other computers and wireless modems in order to have an Internet connection on the tablet。
Some less advertised models have an Ethernet port on one side, and so they are thicker, at least around the port. With this connector you could attach the tablet to an Ethernet cable and so have the network connection without the danger of WiFi. However the production of these models of tablets has stopped last year. Evidently, the manufacturers think that the tablet has to be carried around while the network connection is working, like a cellphone.
When I got the tablet out of the box and turned it on the WiFi subsystem was enabled. Even if I have no WiFi access point in my office, or near my house, the tablet was emitting a lot of EM radiation. I immediately disabled the WiFi system of the tablet. There are a couple of settings for this, that can be different from system to system.
After some minutes however the tablet started to hurt me。 I noticed that it was much much worse than every LCD monitor of much larger size that I tried。 I was worried that the cause was the tablet's CPU and other high frequency circuits。 The CPU frequency of this tablet is 1。5 GHz, so if the CPU leaks some EM radiation it is dangerous。
The next day I tinkered again with the settings of the tablet and inside a hidden part of the settings program I found another group of settings for the 3G link。 This tablet actually can connect to the Internet also by means of the cell phone network, precisely the 3G type, which corresponds to the GSM system in Europe。 Days before, I had read that this tablet could have a 3G internet connection, but I thought that it still needed an external USB key for that。 Instead it seemed that the 3G support was embedded in the tablet, and it was still active。
The moment I disabled the 3G data connection I felt the tablet shutting down something inside, I almost heard a sound of something that was closing, and I noticed the change in the sensation of my head and all upper body. I understood that the 3G system was the reason of the intensity and type of EM radiation from the tablet.
After shutting down also the 3G system I have used the tablet for a few days, to read some books, and try some applications. After some days however I have to conclude that the tablet computer is a too big hazard for my health.
The electromagnetic radiation of the current tablet computers are still too high and dangerous。
Probably the EM radiation comes from the computer part of the tablet ( CPU, RAM, GPU, etc。。。 ), and probably also from the LCD display。 The relatively small LCD display has LED backlight but as we know, LED backlight in commercial displays is powered with high frequency pulsed voltage/current。 Perhaps an OLED display would be better, because it doesn't need a backlight, but not all tablets have OLED displays, and even if the display were OLED type, the computer parts of the tablet are still there。
The tablet casing is entirely made of plastic, which of course doesn't block any EM radiation。 Actually, holding the tablet with a hand for some minutes, makes me feel a strange tingling in my fingers that are on the back side of the tablet。 Perhaps a metal case would be better, but even in that case, the front side is almost open because there is the LCD display。
When the tablet is used for reading while sitting at the desk, the tablet is placed on the table just under the user's head. When it is used to read on a bed or couch, the users hold the tablet even nearer to their face. If the tablet is used while sitting on a chair away from a desk, the users hold the tablet on their stomach, or on their lap. In any position, the tablet is near to the user's body, and the level of EM radiation of the tablet is too high for this.
My conclusions are that tablet computers are dangerous for the user's health, even if all wireless communications are disabled. Current tablet computers of any size, brand or model cannot be used in practice as we would. The level of electromagnetic radiation is still too high for a device that is held near one's body. If you have just to read quickly an information from the tablet, or see a photo, you can do it, but if you want to read a long paper or a book, or see a video, then the tablet is going to damage your body with the electromagnetic radiation of mixed frequencies, up to the GHz range.