Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
1998-01-22
2002-05-21
Hjerpe, Richard (Department: 2774)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S157000, C345S161000, C345S174000, C345S178000, C382S115000, C382S116000, C382S124000
Reexamination Certificate
active
06392636
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to the field of the manual control of a cursor, or pointer on a display screen, such as a computer display monitor or a television (TV) set.
2. Description of the Related Art
The prior art provides two general types of devices that achieve screen cursor/pointer movement control.
In a first type of device, of which a mouse is an example, continuous manual movement of the mouse across a generally horizontal surface is required in order to produce a continuous and corresponding direction of movement of the cursor/pointer across the display screen. This cursor/pointer movement stops when movement of the mouse stops. When the cursor/pointer must be moved a large screen distance, it is usually necessary to lift the mouse off of the surface, and then retrace the mouse over the horizontal surface one or more times.
In a second type of device, of which a joystick is an example, as long as the joystick is manually held in an off-center position, the cursor/pointer continuously moves in a corresponding direction across the screen. In order to stop this cursor/pointer movement, the joystick is returned to its center or neutral position.
The present invention will be described relative to embodiments of a fingertip operated capacitance touchpad whose end-result operation is generally the same as a joystick; however, the spirit and scope of the invention is not to be limited in this manner. That is, a fingertip position on the capacitance touchpad of the present invention produces cursor/pointer screen movement in accordance with the fingertip's position. The present invention finds particular utility in replacing glidepoint and trackpoint devices often found in portable computers, such as laptop computers and palmtop computers.
Embodiments of the present invention relate to a use of, and modifications to, a capacitance distance/fingerprint sensor, such as is described in the above-mentioned related patent application. The general use of capacitance-type sensors is known.
For example, the publication SENSORS AND ACTUATORS, January/February 1989, no.½, at pages 141-153, contains an article entitled INTEGRATED TACTILE IMAGER WITH AN INTRINSIC CONTOUR DETECTION OPTION that was presented at the Fourth International Conference on Solid-State Sensors and Actuators (Transducers '87), Tokyo, Japan, Jun. 2-5, 1987.
This article describes an integrated capacitive tactile imaging sensor that comprises a multi-layer construction having a bottom ceramic support, a 9-row/9-column array of square aluminum electrodes that are contained on a silicon wafer integrated circuit, a flexible and isolating intermediate layer that is made up of natural rubber, a thin conductive rubber layer, and a top protective layer. In this device, capacitance depends upon local deformation of the natural rubber layer. The 81 individual aluminum electrodes of this device provide capacitive measurement of an indentation pattern within the natural rubber layer, this indentation being caused by a pressure distribution that acts on the top protective layer.
The use of a capacitance-type sensor to sense the minutiae of a fingerprint is also known.
For example, the publication IEEE ELECTRON DEVICE LETTERS, VOL. 18, NO. 1, January 1997, pages 19-20, contains an article entitled NOVEL FINGERPRINT SCANNING ARRAYS USING POLYSILICON TFT'S OF GLASS AND POLYMER SUBSTRATES. This article describes a two-dimensional (2-D), 200×200, capacitance sensing array that is made up of 40,000 individual pixels. Each pixel of the array includes two Thin Film Transistors (TFTs) and a capacitor plate. Each array pixel resides at the intersection of an array-row and an array-column, and each array pixel is individually addressable by way of row-driver circuits and column-driver circuits.
Considering the two TFTs, hereinafter called TFT-A and TFT-B that are associated with a given pixel, the drain electrodes of TFT-A and TFT-B are connected to the pixel's capacitor plate, the gate electrode and the source electrode of TFT-A are connected to a row-conductor that is associated with the pixel, the gate of TFT-B is connected to the following row-conductor, and the source of TFT-B is connected to a column-conductor that is associated with the pixel.
A thin (0.1 micrometer) silicon nitride insulator overlies the capacitor plate of each array pixel. When the ridge of a fingerprint lies directly over the capacitor plate, a capacitor is formed between the capacitor plate and the finger. This capacitor is charged when a row-pulse (8 to 10 VDC, and of 10 to 100 microsecond duration) is applied to the pixel by way of the row conductor that is associated with this pixel and TFT-A. This stored charge is thereafter transferred onto the pixel's column-conductor through TFT-B when a row-pulse is applied to the following row-electrode.
Also of interest is the publication 1997 IEEE INTERNATIONAL SOLID-STATE CIRCUITS CONFERENCE that contains an article beginning at page 200 entitled A 390DPI LIVE FINGERPRINT IMAGER BASED ON FEEDBACK CAPACITIVE SENSING SCHEME. This article describes a single-chip, 200×200 element array, 2-metal digital CMOS technology sensor that is based upon feedback capacitance sensing, and that operates to detect the electrical field variation that is induced by the finger's skin surface. In each element of the array, two horizontally spaced metal plates are separated from the overlying and adjacent portion of the finger's skin surface by passivation oxide. Since the distance between the skin and the sensor's surface identifies the presence of the fingerprint's ridges and valleys, an array of elements provides a complete fingerprint pattern.
In each element of the array, the two metal plates are respectively connected to the input and the output of a high-gain inverter, to thereby form a charge integrator. In operation, the charge integrator is first reset by shorting the input and output of the inverter. A fixed amount of charge is then sinked from the input, causing the output voltage to swing inversely proportional to a feedback capacitance value that is inversely proportional to the distance to the fingerprint's ridges and valleys. The array of cells, or sensors, thus provides the complete fingerprint pattern. The fingerprint image disappears when the finger is removed from the array.
U.S. Pat. No. 4,353,056, incorporated herein by reference, is of interest in that it relates to a capacitance-type fingerprint sensor wherein a finger is pressed onto the surface of the sensor in order to read the ridges and valleys of the fingerprint. The sensor surface has a large number of capacitors of a small physical size associated therewith. Two sensors are described. In a first type of sensor, an electrical insulator carries a number of flexible and horizontally spaced curved metal electrodes, and two adjacent metal electrodes which comprise one capacitor. A protective insulating film overlies the electrical insulator, and when a finger is brought into physical contact with this protective insulating film, the metal electrodes are physically deformed, thereby selectively changing the capacitance of the large number of capacitors in accordance with the fingerprint's ridge/valley pattern. In a second type of sensor, the top surface of a rigid support carries a number of horizontally spaced and flat metal electrodes in a fixed position. Placed above the plane of the metal electrodes is the sequential arrangement of a flexible insulator, a flexible electrode, and a flexible protective membrane. A capacitor is formed between the top flexible electrode and each of the lower and fixed position flat metal electrodes. When the end of a finger is brought into contact with the flexible membrane, the flexible electrode becomes wavy in accordance with the fingerprints' ridges/valleys pattern.
In addition, U.S. Pat. No. 5,325,442, incorporated herein by reference, relates to a capacitance-type fingerprint sensor having a sens
Ferrari Alberto
Tartagni Marco
Hjerpe Richard
Jorgenson Lisa K.
Lesperance Jean
STMicroelectronics Inc.
Venglarik Daniel E.
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