Free positioning tilt unit

A free positioning tilt unit for use in portable computer or the like, comprises of main frame, mounting bracket element, sleeve, display unit and bushing, in which the opening, closing and positioning of the display unit is achieved by means of the revolving and positioning of the bushing in the sleeve; the bushing is secured to the display unit by means of the engagement of relative tangent planes so as to follow the display unit to move; a central through-hole is formed, when all the component parts are respectively connected together, for insert therethrough of electric wires.

BACKGROUND OF THE INVENTION 
In regular portable computers, the tilt unit generally utilizes a spring 
type of mechanism to produce torsion for the display unit the drawbacks of 
which may include: (1) Difficulty of securing the torque required since 
the manufacturing tolerance for the spring is difficult to control; (2) 
Difficulty of assembling because many parts are used; and (3) Different 
torque may result for different direction of rotation. 
SUMMARY OF THE INVENTION 
The present invention is to provide a free positioning tilt unit for use in 
a portable computer or the like, to let the display unit of the portable 
computer or the like to position at any angular position by means of the 
revolution and position of a torsion shaft on a sleeve. According to the 
present invention, a free positioning torsion shaft structure is comprised 
of a main frame, a display unit, a bushing, a sleeve and a mounting 
bracket element, in which the bush is secured to the display unit by means 
of the engagement of the external tangent plane of the bushing, and the 
internal tangent plane of the display unit, so as to follow the display 
unit to move synchronously; the mounting beacket element is fixedly 
mounted on the main frame having a semi-circular hole made thereon for 
connection thereto of the curved flange of the sleeve, the sleeve is 
further inserted into the bushing and the torsion shaft is received and 
firmly secured to the axle housing of the display unit to form a free 
positioning tilt unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Turning now to the annexed drawing in detail, therein illustrated is a free 
positioning torsion shaft embodying the present invention and generally 
comprised of a main frame (1), a mounting bracket element (2), a sleeve 
(3), an display unit (4), and a bushing (5). 
The main frame (1) includes two frame assemblies (11) at both sides of 
which each comprises a notch (12), a screw hole (13), and a projecting 
strip (14). The mounting bracket element (2) includes a horizontal base 
portion (21) having an upper end surface (211) and a lower end surface 
(212) to define a gap (213) therebetween, a raised face portion (22) 
extending from the horizontal base portion and arranged at a higher level 
with a round hole (221) made thereon, and a vertical side-wall portion 
upstanding from the horizontal base portion (21) with a semi-circular hole 
(231) made thereon. When the mounting bracket element (2) is set in the 
main frame (1), the projecting strip (14) is inserted in the gap (213) 
between the upper end surface (211) and the lower end surface (212), and 
the bolt hole (13) is disposed to aim at the round hole (221) for 
insertion therethrough of a fastening element (6) to secure the mounting 
bracket element (2) to the main frame (1). The sleeve (3) includes a 
crevice (31) cut therethrough along axial direction, and a curved flange 
(32) extending therefrom at one end. When in assembly, the curved flange 
(32) is inserted into the semi-circular hole (231) of the mounting bracket 
element (2) to secure thereto. The display unit (4) includes two axle 
housings (41) internally at both sides of which each comprises internally 
a tangent plane (42). The bushing (5) comprises externally a tangent plane 
(51) made on the outer wall surface, and internally a flange (52) made at 
one end. When the bushing (5) is inserted into the axle housing (41), the 
external tangent plane (51) of the bushing (5) is engaged with the 
internal tangent plane (42) of the axle housing (41) so that the bushing 
(5) will follow the axle housing (41) of the display unit (4) to move 
synchronously. According to the present invention, the outer diameter of 
the sleeve (3) is slightly larger than the boring bore (53) of the bushing 
(5). When the sleeve (3) is inserted into boring bore (53) of the bushing 
(5), the sleeve (3) is forced to deform. Therefore, a constant downward 
pressure results from in the contact surface between the bushing (5) and 
the sleeve (3). When the bushing (5) and the sleeve (3) are relatively 
revolving against each other, a constant friction force is produced, and a 
constant torque can thus be obtained. Further, the display unit (4) can be 
positioned at any angular position by means of the torque. 
Because of the crevice (31) of the sleeve (3) can be deformed elastically 
during it is inserted into the bushing (5). The effect of the elastic 
deformation forces the sleeve (3) to contact with the boring bore is of 
the bush closely and produces a normal force between two contact surface. 
This normal force generates torque to position the display unit at any 
angular position and this kind of design can generate same torque by no 
means of the rotation direction of the display unit which is rotated 
clockwise. 
When the main frame (1) the mounting bracket element (2), the sleeve (3), 
the bushing (5) and the axle housing (41) of the display unit (4) are 
respectively assembled together, a hollow passage is formed therein for 
insert therethrough of electric wire from the main frame (1) to the screen 
(not shown) made on the display unit (4). Therefore, no additional 
electric wire hole is required. 
According to the present invention and as an alternate for of the present 
invention, the bushing (5) may be secured to the axle housing (41) of the 
display unit (4) by means of a plurality of tangent planes or any other 
shapes of retaining portions respectively made on the axle housing (41) 
and the bushing (5). Further, the curved flange (32) of the sleeve (3) may 
be in a semi-circular shape or any other preferred shape according to 
requirement. 
According to the present invention, the structure of the free positioning 
tilt unit may be utilized in portable computer or any other similar 
products.