Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
2000-04-07
2002-06-04
Wu, Xiao (Department: 2774)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C290S006000
Reexamination Certificate
active
06400354
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a pointing stick device, and more particularly, to a pointing stick device that can effectively sense pressure from its cap.
2. Description of the Prior Art
A pointing stick device can control the movement and function of a cursor on a computer display. The pointing stick device is a common peripheral, used with both desktop and notebook computers. The cursor on the display can have three directions of movement: X, Y and Z. However, the pointing stick device can only control two of these directions, the X and the Y. Consequently, after setting the X and Y position of the cursor, the user must press a button to set the Z direction or to initiate a function.
It has grown increasingly important with pointing stick devices to increase the sensitivity in the X and Y directions, and add sensitivity in the Z direction. Sensitivity in the Z direction enables true 3-dimensional (3D) positioning of the cursor. The Z direction signal can also serve a button-like purpose, initiating functions. With the universality of 3D drawings and 3D animation, the prior art pointing stick device with only a 2-dimensional (2D) signal is no longer sufficient. Consequently, designing a pointing stick device with high sensitivity in the Z direction is very important.
Please refer to FIG.
1
.
FIG. 1
is a cross-sectional diagram of a prior art pointing stick device
10
. The prior art pointing stick device comprises a column-shaped stick
12
for controlling the 2D movement of a cursor (not shown) on a display (not shown). The stick
12
comprises a top end
13
, a bottom end
17
and a portion
15
between the top end
13
and the bottom end
17
. The pointing stick device further comprises a cap
20
mounted on the top end
13
of the stick
12
, a rubber cap
21
mounted on the cap
20
for the user's convenience, a substrate
30
containing an aperture
36
for fixing the stick
12
, a plurality of strain gauges
22
for sensing pressure and generating corresponding sensing signals, a plurality of leads
24
connected to the lower end of the strain gauges
22
, a plurality of traces
32
installed on the substrate
30
and soldered to the leads
24
to transmit the sensing signals of the strain gauges
22
, a collar
28
mounted around the bottom
17
of the stick, and a bonding compound
26
filling the gap between the collar
28
, the stick
12
and the substrate
30
for affixing the bottom
17
of the stick into the aperture
36
of the substrate
30
.
Please refer to FIG.
2
and FIG.
3
.
FIG. 2
is a schematic diagram of the pointing stick device
10
under an external horizontal force. The dashed center-line indicates the bending direction of the stick.
FIG. 3
is a schematic diagram of the pointing stick device
10
shown in
FIG. 1
under an external vertical force. The dashed center-line indicates the direction of compression of the force. When the user pushes the rubber cap
21
, the cap
20
pushes the stick
12
. The stick
12
undergoes bending deformation and the strain gauges
22
sense the induced pressure. The collar
28
helps the strain gauges
22
sense the bending deformation via the bonding compound
26
. When the horizontal force (F
x
, F
y
) bends the stick
12
, the strain gauges
22
generate bending strain signals S
x1
, S
y1
. When the perpendicular force (F
z
) presses on the stick
12
, the strain gauges
22
generate a compressive strain signal S
z1
.
The inner side of the cap
20
of the prior art pointing stick device
10
is a column-shaped mouth
23
and the corresponding portion
15
of the stick
12
is also column-shaped. Consequently, the strain signal S
z1
, which corresponds to the Z direction compression force, is too weak to be used. When the external force pushes the cap
20
, the strain gauges
22
are compressed by the substrate
30
, the collar
28
, and the bonding compound
26
, so they can only generate corresponding 2D strain signals S
x1
, S
y1
. Moreover, the bending stress of the stick
12
is limited, which limits the sensitivity of the strain signal in the horizontal direction. Also, during assembly of the pointing stick device
10
, installation of the bonding compound
26
and the collar
28
is difficult, which increases costs.
SUMMARY OF THE INVENTION
It is therefore a primary objective of the present invention to provide a pointing stick device that can effectively sense the pressure from its cap to solve the above mentioned problems.
In a preferred embodiment, the present invention relates to a pointing stick device comprising:
a base plate;
a stick having a top end, a bottom end, and a middle portion between the top end and bottom end, the bottom end of the stick being vertically installed at the base plate;
at least one strain gauge installed around the top end for sensing pressure and generating corresponding sensing signal;
a cap mounted at the top end of the stick and having a cone-shaped mouth at its lower end for containing the top end of the stick; and
a base stand installed outside the middle portion of the stick and covering at least a portion of the strain gauge, a portion of the base stand being positioned inside the cone-shaped mouth of the cap;
wherein when an external force is applied to the cap, the force will be transmitted through the cone-shaped mouth of the cap to the portion of the base stand positioned inside the mouth and also to the strain gauge covered by the base stand wherein the strain gauge will sense the force from the cap and generate corresponding sensing signals.
It is an advantage of the present invention that it can provide a pointing stick device with increased sensitivity in the X and Y directions, and that can also effectively sense pressure in the Z direction from its cap.
These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description that is illustrated in the various figures and drawings.
REFERENCES:
patent: 5043709 (1991-08-01), Kim
patent: 5754167 (1998-05-01), Narusawa et al.
patent: 6189401 (2001-02-01), Atwell et al.
patent: 6266046 (2001-07-01), Arita
Darfon Electronics Corp.
Hsu Winston
Wu Xiao
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