Laptop Computers have a history of gradual devlopment or birth, as we can call it. The first appearance of a 'clamshell' design, wherein the screen covers the keyboard when folded, was introduced by GRiD Systems Corporation.
The first identified patent is a design patent USD280511 filed on 18th Oct 1982 and issued on 10th Sep 1985.
The drawings of this design patent match the so-called first laptop computer, "Compass".
| Design Patent Drawing |
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| Compass |
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| Design Patent Drawing |
US4571456 was also filed on 18th Oct 1982 along with the design patent mentioned above, but it was issued later on 18th Feb 1986. It describes the first foldable computer system. It majorly focuses on the metal case enclosing the computer parts. The metal case, it discloses, acts as a heat sink for transferring waste heat from heat producing electrical components to the surroundings in the open, operating configuration of the computer.
There are many contenders for being considered as the first laptop computer, based on what you define a laptop computer to be. All such contenders have been done justice in [2].
My choice for considering Compass by GRiD Systems Corporation as the first laptop is its comparatively high resemblance to the modern day laptops in terms of design.
There have been many clamshell based designs for portable computers after this, but this is the first occurence of a 'laptop-like' portable computer.
References
[1] http://wiki.answers.com/Q/Who_invented_the_laptop_computer
[2] http://inventors.about.com/library/inventors/bllaptop.htm