Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1998-11-06
2001-07-03
Shalwala, Bipin (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C382S124000, C178S018060
Reexamination Certificate
active
06256022
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to systems for providing user input to user interfaces for computers and the like, and more particularly to a semiconductor capacitive user input device and method for controlling the position of a cursor or pointer on a display.
DESCRIPTION OF THE PRIOR ART
Pointing devices are commonly used in conjunction with computers to control the movement of graphical cursors or pointers on display screens and to select objects and operate controls displayed on the screen. For desktop computers and work stations, the most commonly used pointing device is a mouse. As is well known, a mouse is moved over a flat surface to control the position of the pointer on the display screen. The mouse includes one or more buttons that may be pressed or clicked to perform operations on objects and controls displayed on the screen.
Recently, small laptop and notebook computers have become very popular. Laptop and notebook computers may be used in conjunction with a docking station so that a standard keyboard, mouse, and CRT display may be used for the user interface. However, laptop and notebook computers are designed to be used while traveling away from the office or home. In such remote locations, the user does not always have available a flat surface upon which to use a mouse. Accordingly, laptop and notebook computers typically have a built-in pointing device, such as a track ball, touchpad, or a pressure-actuated pointer device, such as the IBM TrackPoint(™) device.
In addition to computers, certain television and set top box systems include a graphical user interface for enabling a user to input information to the system and change or control system settings. The user input device for such systems is typically a hand-held infrared keypad controller. Such controllers may include devices similar to those used in laptop and notebook computers to control the position of a pointer on the television screen. Trackballs, touchpads, and pressure-actuated pointing devices have certain drawbacks. For example, while trackballs are compact, they require consider finger movement to produce large pointer displacements at low velocities. In addition, trackballs are mechanical devices that may not be well suited for operation in dirty environments.
A touchpad comprises a rectangular surface that is mapped to correspond to a display screen. By touching the location on the touchpad, the user causes the computer to move the pointer to the corresponding location on the screen. Since a typical touchpad is substantially smaller than the screen, accurate positioning of the pointer can be difficult. In order to be useable, a touchpad must be large enough to permit the user to position the pointer accurately. The large size of touchpads makes them relatively expensive.
Pressure-actuated pointing devices include strain gauges or transducers that detect the direction and magnitude of the force of the user's finger on the device. The pointer is moved in a direction corresponding to the direction of the force and to the speed corresponding to the magnitude of the force. Certain individuals have trouble using pressure-actuated pointing devices to position the pointer accurately on the screen. One source of trouble is inertia, whereby the pointer continues to move after the user releases the pressure on the device.
In U.S. application Ser. No. 09/012,065, filed Jan. 22, 1998, by A. Ferrari and M. Tartagni, entitled “Touchpad Providing Screen Cursor/Pointer Movement Control”, there is disclosed a touchpad device that includes a matrix array of capacitance sensors. The array of the invention can be used initially to acquire a user fingerprint for use in a user identification procedure that occurs during logon to a device such as a laptop or palmtop computer. Subsequently, the array is used to provide user input to the computer. By using the array both for user identification and for user input, the cost of the relatively large array is justified.
In U.S. application Ser. No. 09/006,691, filed Jan. 13, 1998, by Alan Kramer, entitled “Capacitive Semiconductor User Input Device”, there is disclosed a device for providing user input to a computer, or the like, by detecting changes in a fingerprint pattern of a user. The device of application Ser. No. 09/006,691 captures successive images of the fingerprint ridges and pores. The device captures the successive images by scanning an array of sensors, each of the sensors being smaller than the width of an individual ridge of a fingerprint. The array of sensors is substantially smaller than the pad of a finger of a user. The device detects motion of the ridges and pores by comparing the captured successive images.
Since the array of the device of application Ser. No. 09/006,691 is relatively small, it is substantially less expensive to make than a touchpad device. However, capturing and comparing successive images to determine motion is a complex task requiring substantial computer processing. It is therefore an object of the present invention to provide a user input device that overcomes the shortcomings of the prior art.
SUMMARY OF THE INVENTION
The present invention provides a low-cost semiconductor user input device for controlling the position of a pointer on a display. The user input device of the present invention includes a small array of composite sensors. Each composite sensor of the array is adapted to detect movement of a fingerprint feature. The user input device of the present invention moves the pointer based upon the net movement detected by the composite sensors of the array.
Each composite sensor of the present invention includes a central trigger sensor, a pair of X direction sensors disposed on opposite sides of said trigger sensor, and a pair of Y direction sensors disposed on opposite sides of said trigger sensor. Each sensor of each composite sensor is adapted to produce a voltage indicative of the presence of a fingerprint feature in proximity thereto. A fingerprint valley produces a first voltage and fingerprint ridge produces a second voltage.
The user input device detects movement of fingerprint features by detecting transitions from the first voltage to the second voltage at the sensors. A transition detected at a central trigger sensor followed by a transition detected at one of the X or Y sensors indicates movement in the X or Y direction. The movement indicated by each composite sensor is processed to determine the net movement of the fingerprint features and to move the pointer accordingly.
In one of its aspects, the user input device includes averaging circuitry connected in parallel to each sensor of a composite sensor. The averaging circuitry determines the average voltage produced by the sensors of the composite sensor. A comparator is associated with each sensor of the composite sensor. The comparator is connected to its associated sensor and to said averaging circuitry. Each comparator outputs a first value when the sensor to which it is connected produces a voltage less than the average voltage and a second value when the sensor to which it is connected outputs a voltage greater than the average voltage.
The comparators associated with the sensors of each composite sensor are connected to a finite state machine. The finite state machine normally outputs a zero value. The finite state machine is set when the comparator connected to the central trigger sensor makes a transition from the first value to the second value. The finite state machine outputs a plus or minus one value a comparator connected to one of the X or Y sensors makes a transition from the first value to second value while the finite state machine is set. The sign of the output is determined by the position of the sensor making the transition with respect to the trigger sensor. A motion sensor sums the outputs of the finite state machines to determine the magnitude and direction of movement of the fingerprint features over the array of composite sensors.
REFERENCES:
patent: 4353056 (1982-10-01), Tsikos
patent: 447779
Kovaks-Vajna Zsolt Miklos
Manaresi Nicolo'
Rambaldi Roberto
Tartagni Marco
Osorio Ricardo
Shalwala Bipin
STMicroelectronics S.r.l.
Thompson & Knight L.L.P.
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