Pivoting joint

A pivoting joint connected between a first part and a second part of an instrument, permitting the first part to be turned relative to the second part and retained at one of a series of angular positions, including a first coupling member with a ratchet fastened to the first part of the instrument, a shaft mounted in an axle hole in the second part of the instrument, a sleeve and a spring holder mounted around the shaft within the axle hole of the second part of the instrument and forced by spring means to hold down the shaft, and a second coupling member fixedly mounted on the shaft and having a ratchet meshed with the ratchet of the first coupling member.

BACKGROUND OF THE INVENTION 
The present invention relates to pivoting joints, and more particularly to 
such a joint adapted to be connected between a first part and a second 
part of an instrument, for permitting the first part to be pivoted 
manually around one direction relative to the second part and retained at 
one of a series of angular positions, and for obtaining a damping effect 
during a reverse direction pivoting. 
There is known a joint (hinge) adapted to be connected between a cover 
shell of an instrument and a frame thereof, for permitting the cover shell 
to be pivoted relative to the frame, comprised a pivot shaft having a flat 
mounting base at one end fixedly fastened to the cover shell of the 
instrument and a shaft body with an outer thread at an opposite end and a 
collar in the middle, a pivot holder fixedly fastened to the frame of the 
instrument and having a pivot hole coupled to the shaft body of the pivot 
shaft, a nut threaded onto the outer thread of the shaft body of the pivot 
shaft to secure the pivot shaft and the pivot holder together, a plurality 
of washers respectively mounted around the shaft body of the pivot shaft 
and retained between the collar of the pivot shaft and the pivot hole of 
the pivot holder, and two sets of rounded friction spring plates reversely 
mounted around the shaft body of the pivot shaft and retained between the 
washers. The two sets of rounded friction spring plates are forced to 
produce a friction force, causing the pivot shaft to be retained to the 
pivot holder at an angle. This structure of joint is suitable for use in a 
small instrument for example a notebook computer. However, because the 
friction force between the rounded friction spring plates cannot support a 
heavy load, the joint is not suitable for use in a relatively bigger 
instrument for example a copy machine. 
SUMMARY OF THE INVENTION 
The present invention has been accomplished to provide a joint which 
eliminates the aforesaid problem. According to the preferred embodiment of 
the present invention, the joint is connected between a first part and a 
second part of an instrument for example a copy machine, permitting the 
first part to be pivoted around one direction relative to the second part 
and retained at one of a series of angular positions, and obtaining a 
damping force during a reverse direction pivoting comprising: a mounting 
rod fixedly mounted on the first part of the instrument; a first coupling 
member mounted on the mounting rod and prohibited from rotary motion 
relative to the mounting rod, the first coupling member having a ratchet 
at one end; a shaft inserted into an axle hole in the second part of the 
instrument, the shaft comprising a tapered base, a shaft body at one end 
of the tapered base, and a mounting block at an opposite end of the 
tapered base, the shaft body having a first threaded section at one end 
remote from the tapered base, and a second threaded section in the middle 
between the first threaded section and the tapered base; a second coupling 
member fixedly fastened to the mounting block of the shaft, having a 
ratchet at one end adapted to mesh with the ratchet of the first coupling 
member; a sleeve sleeved onto the shaft body of the shaft within the axle 
hole of the second part of the instrument and stopped at the tapered base 
of the shaft, having a longitudinal coupling flange engaged with a 
longitudinal groove in the axle hole of the second part of the instrument; 
two first nuts respectively threaded onto the second threaded section of 
the shaft body of the shaft; a first spring mounted around the shaft body 
of the shaft and stopped between the first nuts and the sleeve, the first 
spring imparting a forward pressure to the sleeve, causing the sleeve to 
engage the tapered base of the shaft; a spring holder mounted around the 
shaft body of the shaft and stopped from axial movement relative to the 
shaft; a second spring mounted around the shaft body of the shaft within 
the spring holder and stopped between the spring holder and the first 
nuts; and a second nut threaded onto the first threaded section of the 
shaft body of the shaft.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIGS. 1 and 2, a joint in accordance with the present 
invention is generally comprised of a mounting rod 1, a first coupling 
member 2, a second coupling member 4, a shaft 19, a sleeve 9, a first 
spring 12, a second spring 15, and a spring holder 14. The shaft 19 
comprises a tapered base 7, a shaft body 8 at one end of the tapered base 
7, and a mounting block 5 at an opposite end of the tapered base 7. The 
mounting block 5 of the shaft 19 has a transverse groove 6, and a screw 
hole 61 at the center of the transverse groove 6. The shaft body 8 has a 
first threaded section 82 at one end remote from the tapered base 7, and a 
second threaded section 81 in the middle between the first threaded 
section 82 and the tapered base 7. The second coupling member 4 is fixedly 
secured to the screw hole 61 of the mounting block 5 of the shaft 19 by a 
screw 21, having a transverse rib 40 at one end fitted into the transverse 
groove 6 of the head 5 of the shaft 19, and a ratchet 30 at an opposite 
end. The sleeve 9 is sleeved onto the shaft 19, and stopped at the tapered 
base 7. The first spring 12 is mounted around the shaft body 8 of the 
shaft 19. Two first nuts 13 are threaded onto the second threaded section 
81 to hold down the first spring 12, permitting the first spring 12 to be 
stopped between the first nuts 13 and the sleeve 9. Two washers 11 are 
respectively mounted around the shaft body 8 of the shaft 19 and retained 
to two opposite ends of the first spring 12. The spring holder 14 is 
mounted around the shaft body 8 of the shaft 19 to hold the second spring 
15, permitting the second spring 15 to be retained between the spring 
holder 14 and the first nuts 13. A second nut 130 is threaded onto the 
first threaded section 82 to hold down the spring holder 14. Further, the 
spring holder 14 has an annular groove 20 around the periphery; the sleeve 
9 has a longitudinal coupling flange 10 raised from the periphery along 
its length. 
Referring to FIG. 3 and FIG. 2 again, when the second coupling member 4, 
the shaft 19, the sleeve 9, the first spring 12, the second spring 15 and 
the spring holder 14 are assembled, the assembly is mounted in an axle 
hole 170 in a frame 16, permitting the longitudinal coupling flange 10 to 
be forced into engagement with a longitudinal groove 17 in the axle hole 
170 of the frame 16, and then a holding down screw 210 is threaded into a 
transverse screw hole 160 in the frame 16 and stopped at the annular 
groove 20 of the spring holder 14 to stop the assembly from axial movement 
relative to the frame 16. The mounting rod 1 is fixedly fastened to a 
cover shell 18. The first coupling member 2 is fastened to the mounting 
rod 1 and prohibited from rotary motion relative to the mounting rod 1, 
having a ratchet 3 adapted to mesh with the ratchet 30 of the second 
coupling member 4. The aforesaid frame 16 and cover shell 18 are members 
of parts of for example a copy machine, i.e., the frame 16 is a part of 
the machine base of the copy machine and the cover shell 18 is a part of 
the cover of the copy machine. 
Referring to FIG. 4 and FIG. 3 again, the first spring 12 imparts a forward 
pressure to the sleeve 9, causing it to push the shaft 19 forwards 
(because the front end of the sleeve 9 is engaged with the periphery of 
the tapered base 7 of the shaft 19), and therefore the ratchet 30 of the 
second coupling member 4 is forced into engagement with the ratchet 3 of 
the first coupling member 4 to hold the cover shell 18 in position. When 
the cover shell 18 is lifted, less friction force exists between the 
ratchets 3;30 (because the teeth of each ratchet slope in one direction), 
therefore the first coupling member 3 is turned with the coupling rod 1 
and the cover shell 18 relative to the second coupling member 4 and the 
frame 16 (see FIG. 3). When the hand is released from the cover shell 18, 
the ratchets 3;30 are meshed again to hold the cover shell 18 at the 
adjusted angle. When the cover shell 18 is turned inwards to the close 
position and the turning force surpasses the friction force between the 
sleeve 9 and the tapered base 7 of the shaft 19, the second coupling 
member 4 and the shaft 19 are turned with the first coupling member 2. 
While only one embodiment of the present invention has been shown and 
described, it will be understood that various modifications and changes 
could be made thereunto without departing from the spirit and scope of the 
invention disclosed.