Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2001-01-11
2004-01-20
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S179000, C345S174000
Reexamination Certificate
active
06680731
ABSTRACT:
BACKGROUND
1. The Field of the Invention
This invention relates generally to combining computer input devices such as keyboards and touchpads. More specifically, the invention relates to combining the existing components of a keyboard and an integrally constructed touchpad, and for an improved system for coupling a PC board with touchpad circuitry to the keyboard components. The invention also relates to combining a flexible sensor portion of a touchpad, and the rigid circuit component portion of the touchpad, to each other
2. The State of the Art
The prior art includes systems which provide a computer input device having an integrated touchpad. For example, the prior art includes kiosks, computer keyboards, and information appliances that utilize touchpads as an input interface. Probably the most common device is a computer keyboard. It is well known in the art of keyboards and touchpads that they can be included within a same keyboard case or chassis. For example,
FIG. 1
shows a top view of a typical QWERTY arranged keyboard
10
from the prior art which has moved the 10-key numeric pad
12
closer to the letter keys, and disposed a touchpad
14
into its place.
FIG. 2
is another keyboard
18
from the prior art which utilizes an ergonomic design. These keyboards
18
have a touchpad
20
disposed beneath the keys in a wrist resting area. This arrangement enables the 10-key keypad
22
to remain in its most familiar location in the keyboard
18
.
Unfortunately, disposing a touchpad into a keyboard is not always a straightforward task for some important reasons. For example, it is obviously desirable to make keyboards as inexpensively as possible. While touchpads also have component costs, they also have certain configuration requirements that are different and often more costly than those of keyboards. These aspects will be discussed after explaining the internal structure of a typical prior art keyboard.
FIG. 3
is provided to illustrate one method of manufacturing the internal structure of keyboards. In this figure, the internal layout of the keyboard is shown as being made using several layers of sheets made from a plastic-like material such as mylar. The sheets are generally non-conductive in nature. A first sheet
30
has a plurality of electrical traces
32
laid out using a conductive material such as carbon ink or silver ink. The electrical traces
32
intersect locations that keys make contact with on the first sheet
30
when the keys of a keyboard are depressed. The ink can also be disposed on the mylar using a simple silk screening process.
It is important to understand that this ink application process is not extremely precise, and therefore is generally used in processes where tolerances are high, such as on keyboard electrical traces. The third mylar sheet
36
also has electrical traces
38
which intersect each of the locations of the keys of the keyboard as do the electrical traces
32
of the first sheet
30
, but typically in a different axis.
The second or middle mylar sheet
40
is used to separate the first sheet
30
from the third sheet
36
when a key is not being pressed. A plurality of holes
42
are made in the second sheet
40
which also correspond to the locations of keys of the keyboard. Thus, when a key is pressed, an electrical trace
32
on the first sheet
30
is pressed into contact with an electrical trace
38
on the third sheet
36
as made possible because of a corresponding hole
42
in the middle or third sheet
36
. This pressing together of a set of electrical traces
32
,
38
at a unique location completes an electrical path which is sensed by keyboard circuitry in order to determine which key was pressed. The keyboard circuitry is at least one integrated circuit which is located on a PC board which is separate from the plastic sheets
30
,
36
,
40
.
Having explained typical internal structure and operation of a prior art keyboard, the addition of a touchpad complicates construction because touchpads typically require a rigid PC board as part of the sensing circuitry. For example, a capacitance sensitive touchpad generally requires a PC board to be used as the surface upon which sensing electrodes are disposed. The reason for using the PC board is that the relative positions of the electrodes typically require great precision because prior art touchpad sensing circuitry does not have large manufacturing error tolerances. This intolerance to manufacturing irregularities is generally a function of the touchpad circuitry itself. Touchpad circuitry is inherently sensitive to electrical noise, electrode spacing, and other factors that inhibit the ability to accurately detect and determine the location of a pointing object on the touchpad surface.
For example, X and Y electrical traces are laid out in a very precise pattern or grid. The error tolerance (dynamic range) of all touchpad circuits known to the inventors are such that without a precise grid layout that can only be consistently achieved using a PC board, the touchpads will not function. In other words prior art touchpad are generally so sensitive that it is necessary to include a PC board for the touchpad sensing electrode grids inside the keyboard case if a touchpad is to be included.
In examining the construction of prior art keyboards which include a touchpad, the plastic sheets are typically moved out of the way or minimized in size in order to make room for a PC board that is used for the touchpad sensing electrodes. This is the case with the touchpad shown in FIG.
1
. In
FIG. 2
, the larger size of the ergonomic keyboard allows a PC board to be included without major modifications, but still requires the use of a large PC board for the touchpad. It is also necessary to cut an aperture through the keyboard case to thereby expose the touchpad surface to the pointing object.
In addition to the inclusion of a PC board for the touchpad sensing electrode grids, it is necessary to include some means for connecting the electrical traces
32
,
38
on the plastic sheets
30
,
36
,
40
to control circuitry. The control circuitry is mounted on PC boards inside the keyboard case. This connecter has to be relatively strong because of the nature of the materials being used.
For example, the ink used in the electrical traces can oxidize. Accordingly, a connecter is used which applies a relatively large amount of pressure to force the electrical traces against corresponding electrical traces on a PC board. This pressure typically overcomes the oxidation, but requires the extra hardware involved in making the pressure connection.
It would be an advantage over the prior art to provide a means for reducing the amount of PC board required for a touchpad that is mounted inside a keyboard case. It would be another advantage to improve the connection interface between a PC board and the plastic sheets of the keyboard. It would be another advantage to utilize the plastic sheets for the touchpad sensor electrodes of the touchpad, thereby reducing cost and complexity of the keyboard. Another advantage would be to provide a new way to mount the touchpad sensor electrodes to a keyboard case, regardless of the presence of the plastic sheets for the keyboard itself. Finally, it would be an advantage to provide the touchpad sensor electrodes on a flexible material such as the plastic or mylar sheets, to thereby enable the touchpad to conform to curved surfaces, such as the inside of a keyboard case.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the present invention to provide a flexible surface on which the touchpad sensor electrodes are disposed, to thereby enable the surface of the touchpad to be disposed along arcuate surfaces.
It is another object to integrate a touchpad and a keyboard in a keyboard case, wherein the touchpad replaces PC board material normally used for the touchpad sensor electrodes, with the plastic sheets used in construction of the key sensing apparatus.
It is another object to improve the connection between a PC board and plastic sheets used for the to
Gerpheide George
Lee Daniel
Taylor Brian
Woolley Richard
Alphonse Fritz
Cirque Corporation
Morriss O'Bryant Compagni, P.C.
Saras Steven
LandOfFree
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