Our invention relates to friction hinges used to position electronic displays for best viewing, and to cam mechanisms as applied to holding shut a cover or lid without a latch mechanism.
Laptop and portable computers, herein referred to as laptops, have displays built into their lids, which usually are closed while the computers are being moved. The lids of prior art laptops are held shut with latch mechanisms. Extra hand movements are usually required to open latch mechanisms, and extra parts are required in the computer for the mechanisms are required in the computer for the mechanisms themselves. In addition, the latch mechanisms are somewhat prone to breakage. Therefore, it is advantageous to be able to hold laptop lids shut without the requirement for latch mechanisms.
If a laptop that is to be held shut by some mechanism other than a latch, it must remain firmly shut when the laptop is carried. The lid must not open, even slightly, during normal movements of the laptop. On the other hand, when the laptop is being prepared for use, the lid should open as easily as possible, preferably without requiring the use of two hands, one to lift the lid, and the other to hold down the base of the laptop.
There is a further requirement for controlling the position of the lid for a laptop. In use, the lid must remain in position. Laptop lids are positioned by the user. Desirably, this positioning should be done easily without the need for holding down the base while positioning the lid. Furthermore, once positioned for advantageous viewing, the lid should remain in position, without creeping or excessive bouncing. This requires the use of friction hinges for mounting the lid to the base. All present day laptops employ such hinges.
All friction hinges exhibit some amount of spring back. When laptops having such hinges but no latch mechanism are closed, they spring open slightly due to the strain energy stored in the spring element that produces the hinge""s friction. Furthermore, the torque holding the lid in position is limited to the torque provided by the friction hinges. This torque is inadequate for keeping the lid firmly closed while carrying the laptop. Therefore, additional closing torque, beyond that provided by the friction hinge is needed to keep the lid tightly closed.
A cam, which engages a spring-loaded follower as the lid is closed, can provide additional closing torque so that the latch can be eliminated. However, the closing torque produced by the cam device must be sufficiently great so as to overcome all of the torque of the friction hinge. That requirement demands that the hinge and its attachment to the lid and base be sufficiently robust.
However, the additive nature of the cam and friction forces requires that the torque to open the lid overcome both the cam-induced lid closing force and the frictional torque. This fact makes it difficult to balance these torques so as to prevent lifting the base while lifting the lid. Thus, two hands are required, one to open the lid and the other to hold down the base. A hinge which eliminates this conflict between the cam and frictional torque is the goal of our invention.
Our invention consists of a hinge with a cam mechanism to provide the torque needed to hold the lid closed and a band wrapped about a shaft to provide torsional friction to maintain the position of the lid when it is open. The cam mechanism consists of a cam and an engaging member. The engagement and disengagement of the engaging member by the cam results in an increase in closing effort followed by a decrease and finally a snapping closure of the lid. The friction band is so formed and aligned rotationally with features of the shaft that the there is a sudden and steep reduction of the frictional torque at the time of follower engagement so as to permit the cam mechanism to act with maximum effect.
Accordingly, it is an object of the invention to provide an alternative hinge-closing mechanism for a laptop computer.
It is also an object of our invention to provide a lid positioning and closing mechanism that is beneficially usable in other equipment.
It is a further object of our invention to provide the means by which a laptop computer can be opened and their lids positioned with one hand.
It is a still further object of our invention to provide a lid positioning and closing mechanism for laptop computers and other, similar equipment that allows the elimination of the latch mechanism for the lid.
The inventive hinge-closing mechanism accordingly comprises the features of construction, combination of elements, and arrangement of parts which will be exemplified in the constructions described hereinafter, and the scope of the invention will be indicated in the claims.