Computer graphics processing and selective visual display system – Display peripheral interface input device – Cursor mark position control device
Reexamination Certificate
1998-11-18
2001-06-05
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Cursor mark position control device
C073S862044, C345S161000
Reexamination Certificate
active
06243077
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applcable
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The present invention relates generally to pointing devices for use in connection with computers and other electronic instruments and devices. More specifically, the present invention relates to a pointing device used to move a pointer or cursor on a display of a computer or similar electrical or electronic device or instrument.
Many operations relating to the use of modern computers, and in particular personal computers, require that a pointer or cursor be placed in a particular location on a display screen. In addition, many computer-operated and video games are operated based on positioning the cursor or pointing device in a particular location.
In some applications, the position of the cursor may be governed by a touch pad, which is a small touch-sensitive pad embedded in the casing of the device or instrument. Pressure applied to different portions of the pad controls the movement of the cursor on the screen.
In other applications, a joystick is used to control the movement of the cursor. On some laptop computers, this joystick may be a very small device positioned between several of the keys on the keyboard. The computer user manipulates such a small joystick by the end of the user's finger. On many computer games, and in other applications, the joystick may be somewhat larger, and be manipulated by the user grasping the entire joystick with the user's hand. Other applications may use joysticks of different sizes to manipulate a position indicator on the screen. The present invention will be described in connection with its application to joysticks.
The position of the joystick, and its movement relative to its central “rest” or “neutral” position, should be identified so that such position information can be transferred to place the cursor at the appropriate spot on the computer screen or display. A variety of devices have been designed for detecting the position of a joystick. One particular mechanism for a pointing device is described in U.S. Pat. No. 5,640,178 to Endo et al. This reference describes a joystick mounted on a resilient substrate. Strain gauges are formed on one surface of the substrate. A voltage is applied across a pair of the strain gauges in a particular direction, and the voltage at a half bridge output terminal between the strain gauges is measured. From this voltage, the amount of strain on each of the strain gauges of the pair may be determined. From that information, position information can be interpreted. However, this measurement technique requires that the strain gauges of the pair be exactly matched, with exactly equivalent properties. In one embodiment, the strain gauges are formed in a particular configuration so they can be laser trimmed to ensure that the strain gauges have identical properties.
SUMMARY ON THE INVENTION
The present invention is a pointing device that measures strain on a substrate, and a method of operating such a pointing device. The strain gauges are configured as a series of voltage dividers across the substrate surface in a pattern that will allow the changes in the resistances of the strain gauges to be measured. From that determination, the position and displacement of the pointing device can be defined.
In accordance with the present invention, a plurality of perimeter contact points is formed on the substrate surface, as is a plurality of strain gauges. Each strain gauge electrically connects a central contact point with one of the perimeter contact points. A controller circuit connected to a voltage source successively connects the voltage source across selected pairs of the perimeter contact points, and then detects the voltage at the central contact point between the strain gauges that are connected between the perimeter contact points across which the voltage source is connected. Different patterns of high and low voltages are connected to the perimeter contact points to establish the voltages across the different pairs of strain gauges.
In one particular embodiment, the strain gauges of the pointing device are formed of strain-sensitive ink applied to the substrate surface. In another embodiment, a resistor having a known resistance is connected to the central contact point and the voltage is applied across that known resistance as well as the strain gauge resistances to determine a force applied along an additional axis. In still another embodiment, a resistor having a known resistance is connected in series with one of the pairs of strain gauges to measure the amount of strain when the strain gauges are stressed in the same direction. The voltage drop across each of the strain gauge resistors is measured to determine the force on each of the three axes.
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Cheal Blake
Manara Alan
Scofield Michael C.
Bell Paul A.
Boourns, Inc.
Klein & Szekeres LLP
Saras Steven
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