JP2009540452A - Fingertip touch recognition for digitizers - Google Patents

Abstract

A method for verifying fingertip touch input to a digitizer, the step of detecting a pattern of a signal obtained from a conductive line of a digitizer sensor, the step of comparing the pattern with a predetermined fingertip characteristic, and the comparison Recognizing a fingertip touch input based on the method.
[Selection] Figure 6

Description

  The present invention relates to a digitizer, and more particularly to a fingertip touch sensitive digitizer.

  Touch technology is commonly used as an input device for various products. The use of various types of touch devices has increased rapidly due to the advent of new portable devices such as personal digital assist (PDA), tablet PCs, and wireless flat panel display (FPD) screen displays. These new devices are usually not connected to a standard keyboard, mouse, or similar input device that is considered to limit their mobility. Instead, they tend to use some kind of touch input technology. A stylus and / or fingertip can be used for user interaction.

  Both are N-trig Ltd. U.S. Pat. No. 6,690,156 and "Transparent Digitizer 33", entitled "Physical Object Location Apparatus and Method and a Platform using the same" Describes an electromagnetic method for determining the position of a physical object on an FPD, and a transparent digitizer that can be incorporated into an electronic device, typically with an active display screen. Digitizer sensors include a matrix of vertical and horizontal conductive lines and sensors that sense electrical signals. When a physical object is placed at a specific position on the digitizer, a signal is induced, and the starting position can be detected.

  US Patent Application Publication No. 20040155871, referred to as “Touch Detection for a Digitizer”, assigned to N-trig Ltd and incorporated herein by reference in its entirety, uses physical sensing and fingertips using the same sensing conductor. A digitized tablet system capable of detecting both positions of a touch is described. In general, the system includes a transparent sensor placed over the FPD. The digitizer sensor includes a matrix of vertical and horizontal conductive lines that sense electrical signals. When the digitizer is touched at a specific position, a signal is induced and the starting position can be detected.

  U.S. Patent Application Publication No. 20060125580, referred to as “Automatic switching for a dual mode digitizer,” assigned to N-trig and incorporated herein by reference in its entirety, describes various types of user interaction in a digitizer system, For example, a method using an electromagnetic stylus and touch is described. A method for “palm rejection” is described that is based on the size of the detection area of the touch and thus distinguishes between local touch events and global touch events.

  Aspects of some embodiments of the present invention provide systems and methods for verifying that the signal input to the digitizer is a fingertip touch, for example, a touch intended by a user for user interaction. Verification that the signal input to the digitizer is a fingertip touch is not intended by the user for user interaction, e.g., due to a hand resting on the digitizer or mechanical changes between the digitizer and the LCD, This results in distinguishing the fingertip touch input from other detection signals on the digitizer. In some embodiments of the present invention, verification that the signal input to the digitizer is a fingertip touch is facilitated by recognition of one or more predetermined patterns of signals received on the digitizer grid. The An exemplary embodiment of the present invention describes a pattern used to verify that a signal input to a digitizer is a fingertip touch.

  In some embodiments of the invention, the predetermined signal pattern used to verify the fingertip touch is detected on an array of conductive lines of the digitizer grid, eg, an array of four conductive lines, and Or a pattern of signal amplitudes detected at the output of an array of differential amplifiers associated with a conductive line, for example an array of four differential amplifiers. In some exemplary embodiments, the predetermined pattern consists of a pattern of signal amplitude output on both the vertical and horizontal conductive lines of the digitizer grid. In some exemplary embodiments, the predetermined pattern is comprised of signal amplitudes that are higher than one or more predefined thresholds. In some exemplary embodiments of the invention, a predetermined signal pattern is determined to determine the area on the digitizer grid where the input signal was detected and to verify that the signal input to the digitizer is a fingertip touch. Used with recognition. In some exemplary embodiments of the present invention, predetermined signal pattern recognition is performed to determine that the portion of the input signal detected is determined and to verify that the signal input to the digitizer is a fingertip touch. Used with.

  In some embodiments of the invention, the predetermined signal pattern used to verify fingertip touch is a signal amplitude gradient pattern, for example, a spatial gradient detected with an array of conductive lines in a digitizer grid, and And / or a spatial gradient pattern of the output of the differential amplifier. In some exemplary embodiments, the predetermined pattern consists of a pattern of signal amplitude gradients on both the vertical and horizontal conductive lines of the digitizer grid. In some exemplary embodiments, the predetermined pattern is comprised of signal amplitude gradients that are higher than one or more predefined thresholds.

  In some exemplary embodiments of the invention, a predetermined signal pattern is determined to determine the area on the digitizer grid where the input signal was detected and to verify that the signal input to the digitizer is a fingertip touch. Used with recognition. In some exemplary embodiments of the present invention, predetermined signal pattern recognition is performed to determine that the portion of the input signal detected is determined and to verify that the signal input to the digitizer is a fingertip touch. Used with.

  In some embodiments of the invention, the predetermined signal pattern used to verify fingertip touch includes a pattern of signal amplitude and signal amplitude gradient detected on the array of conductive lines of the digitizer grid. . In some exemplary embodiments, the predetermined signal pattern used to verify fingertip touch includes a relationship between signal amplitude and signal amplitude gradient.

  In some embodiments of the invention, the predetermined signal pattern used to verify the fingertip touch includes a relationship between patterns on the orthogonal axes, eg, the horizontal axis and the vertical axis of the digitizer grid. In some exemplary embodiments, the pattern is a signal amplitude pattern. In some exemplary embodiments, the pattern is a signal amplitude gradient pattern. In some exemplary embodiments of the invention, the relationship is a size relationship of the portion from which the input signal was detected. In some exemplary embodiments of the invention, a predetermined signal pattern is determined to determine the area on the digitizer grid where the input signal was detected and to verify that the signal input to the digitizer is a fingertip touch. Used with recognition.

  An aspect of some embodiments of the present invention is a method for verifying fingertip touch input to a digitizer, the method comprising: detecting a pattern of a signal obtained from a conductive line of a digitizer sensor; A method is provided that includes comparing to a fingertip characteristic provided and recognizing a fingertip touch input based on the comparison.

  Optionally, the conductive lines are parallel conductive lines.

  Optionally, the conductive lines include two orthogonal sets of parallel conductive lines forming a grid.

  Optionally, the two orthogonal sets are electrically separated from each other.

  Optionally, the parallel conductive lines are equally spaced.

  Optionally, the parallel conductive lines are arranged at 4 mm intervals.

  Optionally, parallel conductive wire pairs are input to the differential amplifier.

  Optionally, the pattern is a differential amplifier output pattern.

  Optionally, the parallel conductive line pairs are non-adjacent conductive lines.

  Optionally, the pattern is a signal amplitude pattern.

  Optionally, the pattern is a signal amplitude pattern that is higher than a predetermined amplitude threshold.

  Optionally, the pattern is a signal amplitude gradient pattern.

  Optionally, the pattern is a signal amplitude gradient pattern that is higher than a predetermined gradient threshold.

  Optionally, the method includes determining the number of gaps in the signal pattern.

  Optionally, the method includes determining a maximum number of gaps and satisfying the requirement that the pattern of signals verify the fingertip touch with a lower number of gaps.

  Optionally, the signal pattern is detected using a capacitive touch method.

  Optionally, the signal amplitude gradient is a spatial high pass filter signal of the signal pattern.

  Optionally, the pattern is a contour pattern.

  Optionally, the method includes determining a ratio of the size of the area in which the digitizer sensor is detected, and defining a ratio range that satisfies the requirements for verifying fingertip touch.

  Optionally, the method includes determining a region where a signal is detected on the digitizer sensor and determining a range of regions that satisfy the requirements for verifying fingertip touch.

  Optionally, the digitizer sensor is transparent.

  Optionally, the detection includes multi-touch detection.

  An aspect of some embodiments of the invention includes a digitizer sensor that includes a plurality of conductive lines and a controller that operates to verify fingertip touch input based on detection of a pattern of outputs from the plurality of conductive lines. A system for verifying fingertip touch input to a digitizer is provided.

  Optionally, the plurality of conductive lines includes parallel conductive lines.

  Optionally, the plurality of conductive lines includes two orthogonal sets of parallel conductive lines forming a grid.

  Optionally, the two orthogonal sets are electrically separated from each other.

  Optionally, the plurality of conductive lines are equally spaced.

  Optionally, the plurality of conductive lines are arranged at 4 mm intervals.

  Optionally, parallel conductive wire pairs are input to the differential amplifier.

  Optionally, the pattern is a differential amplifier output pattern.

  Optionally, the parallel conductive line pairs are non-adjacent conductive lines.

  Optionally, the controller is operative to determine a pattern of signal amplitude from the output.

  Optionally, the controller is operative to determine a pattern of signal amplitude from an output above a predetermined amplitude threshold.

  Optionally, the controller is operative to determine a pattern of signal amplitude gradients from the output.

  Optionally, the controller is operative to determine a pattern of signal amplitude gradients from outputs that are above a predetermined gradient threshold.

  Optionally, the controller is operative to determine the number of gaps in the signal pattern.

  Optionally, the controller is operative to reject input signals corresponding to patterns having gaps above a predetermined maximum number of gaps.

  Optionally, the output pattern is detected using a capacitive touch method.

  Optionally, the signal amplitude gradient is an output high pass filter signal.

  Optionally, the pattern is a contour pattern.

  Optionally, the controller determines a ratio of the size of the region in which the output is detected, and determines whether the ratio is within a predetermined ratio that meets the requirements for verifying fingertip touch. To work.

  Optionally, the controller determines whether the area is within a predetermined area that satisfies the requirements for verifying fingertip touch, and the size satisfies a predetermined condition for verifying fingertip touch. It operates to determine whether it is within the range of the size of.

  Optionally, the digitizer sensor is transparent.

  Optionally, the controller is operative to detect multi-touch input.

  Optionally, the system comprises a host computer, which communicates with the controller.

  Optionally, the controller sends the verified input as a fingertip input to the host computer.

  The subject matter of the present invention is particularly and clearly claimed in the concluding portion of the specification. Non-limiting examples of embodiments of the present invention are described below with reference to the drawings attached hereto and listed in the brief description of the drawings. In the figures, identical structures, elements or parts that appear in more than one figure are generally labeled with the same reference in all the figures in which they appear. The size of the components and features shown in the figures are selected for ease of presentation and are not necessarily shown to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity.

FIG. 1 is an exemplary simplified block diagram of a digitizer system according to some embodiments of the present invention. FIG. 2 is an exemplary simplified circuit diagram for touch detection according to some embodiments of the present invention. FIG. 3 is an exemplary simplified circuit diagram of a digitizer sensor including a differential amplifier according to an embodiment of the present invention. FIG. 4 is a schematic diagram of a digitizer sensor for fingertip touch detection based on a capacitive touch method for detecting fingertip touch according to some embodiments of the present invention. FIG. 5A is a schematic diagram of an exemplary signal pattern of signal amplitude obtained from fingertip touch detection, according to some embodiments of the present invention. FIG. 5B is a schematic illustration of an exemplary signal pattern of signal amplitude gradients obtained from fingertip touch detection, according to some embodiments of the present invention. FIG. 6 is an exemplary flowchart describing a method for verifying that digitizer signal detection is fingertip touch detection, according to an exemplary embodiment of the present invention. FIG. 7A is a schematic illustration of an exemplary signal pattern for a fingertip touch showing a pattern of amplitude values higher than a predetermined amplitude threshold, according to an exemplary embodiment of the present invention. FIG. 7B is a schematic illustration of an exemplary signal pattern for a fingertip touch showing a pattern of gradient values above a predetermined gradient threshold, according to an exemplary embodiment of the present invention. FIG. 8A is a schematic diagram of an exemplary signal pattern of signal amplitudes obtained from hand touch detection, according to some embodiments of the present invention. FIG. 8B is a schematic illustration of an exemplary signal pattern of signal amplitude gradients obtained from hand touch detection, according to some embodiments of the present invention. FIG. 8C is a schematic diagram of an exemplary signal pattern for hand touch detection showing a pattern of amplitude values higher than a predetermined amplitude threshold, according to some embodiments of the present invention. FIG. 8D is a schematic diagram of an exemplary signal pattern for hand touch detection showing a pattern of gradient values above a predetermined gradient threshold, according to an exemplary embodiment of the present invention. FIG. 9 is an exemplary flowchart describing a method for verifying that digitizer signal detection is fingertip touch detection, in accordance with another exemplary embodiment of the present invention.

  It will be understood that the elements shown in the figures are not necessarily drawn to scale for simplicity and clarity of the drawings. Further, where considered appropriate, reference numerals may be repeated among the figures to indicate corresponding or analogous elements.

  The following description describes exemplary, non-limiting examples of the invention that incorporate various aspects of the invention. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the embodiments. However, it will be apparent to those skilled in the art that the present invention may be practiced without the specific details presented herein. Furthermore, well-known features may be omitted or simplified in order not to obscure the present invention. Features shown in one embodiment can be combined with features shown in other embodiments. Such features will not be repeated for clarity of presentation. Furthermore, some embodiments describe some non-essential features.

  Reference is now made to FIG. 1 showing an exemplary simplified block diagram of a digitizer system according to some embodiments of the present invention. The digitizer system shown in FIG. 1 may be suitable for any computing device that allows interaction between the user and the device, for example a portable computing device including an FPD screen. Examples of such devices include tablet PCs, pen-enabled laptop computers, PDAs or any handheld device such as a palm pilot and a mobile phone. In some embodiments of the present invention, the digitizer system includes a grid-based sensor 12 that is optionally transparent and typically placed over the FPD 10. The ASIC 16 includes circuitry that processes the output and samples it into a digital representation. The digital output signal is forwarded to a digital unit 20, for example a digital ASIC unit, for further digital processing. In some embodiments of the present invention, the digital unit 20 together with the ASIC unit 16 is a controller for the digitizer system and / or has a controller function. Once the result is determined, it is transferred to the host 22 via the interface 24 for processing by the operating system or any current application. In some embodiments of the present invention, the control function is included in the host 22 or only in the host 22.

  In some embodiments of the invention, the sensor 12 is a grid of conductive lines patterned from a conductive material, optionally indium tin oxide (ITO), patterned on a foil or glass substrate. . The conductive lines and foil are optionally transparent. In general, the grid is made of two layers that are electrically separated from each other. In general, one of the layers includes a set of equally spaced parallel conductors, and the other layer includes a set of equally spaced parallel conductors orthogonal to the first set of layers. In general, the parallel conductors are straight lines with equal intervals, and are input to an amplifier included in the ASIC unit 16. Optionally, the amplifier is a differential amplifier. In general, the parallel conductors are optionally arranged at a spacing of about 4 mm, for example 2-8 mm, depending on the size of the FPD.

  In general, the ASIC unit is connected to the output of the various conductors of the grid and functions to process the signal received in the first processing stage. As indicated above, the ASIC unit 16 includes an array of amplifiers, eg, differential amplifiers, for amplifying the sensor signal. In addition, the ASIC unit 16 includes one or more filters to remove irrelevant frequencies. Optionally, filtering is performed before sampling. The signal is then sampled by A / D, optionally filtered by a digital filter, and forwarded to a digital ASIC unit for further digital processing.

  In some embodiments of the present invention, the digital unit 20 reads the sampled data and processes it to determine the position of physical objects such as stylus and / or finger touch. The calculated position is transmitted to the host computer via the interface 24. In some embodiments, the digital unit 20 generates and manages trigger pulses that are provided to the excitation coil 26 surrounding the sensor placement and display screen. The excitation coil provides a trigger pulse that excites the passive circuitry of the stylus that generates a response from the stylus that can be detected later. In some embodiments, the digital unit 20 generates and manages trigger pulses to at least one of the conductive lines.

Stylus detection In some embodiments of the present invention, the stylus is a passive element. Optionally, the stylus includes a resonant circuit that is triggered by the excitation coil 26 and oscillates at its resonant frequency. Optionally, the stylus can include an energy pickup unit and an oscillator circuit. At the resonant frequency, the circuit generates vibration that continues after the end of the excitation pulse and gradually decays. Damping vibrations induce a voltage on adjacent conductive lines, which are detected by sensor 12. In some embodiments of the invention, two parallel sensor lines that are close to each other but not adjacent are connected to the positive and negative inputs of the differential amplifier, respectively. The amplifier can thus generate an output signal that is an amplification of the difference between the two sensor line signals. An amplifier having a stylus on one of the two sensor lines produces a relatively high amplitude output.

Fingertip Touch Detection Reference is now made to FIG. 2 showing an exemplary circuit diagram for touch detection according to some embodiments of the present invention. Conductive lines 310 and 320 are parallel non-adjacent lines of sensor 12. In some embodiments of the present invention, conductive lines 310 and 320 are queried to determine if a finger is present. In order to interrogate a conductive line pair, a signal source Ia, for example an AC signal source, induces an oscillating signal in the line pair. The signal is referenced to the common ground 350. When a finger is placed on the one pair of conductive wires, the capacitance C _T is generated between the finger and the conductive line 310. Since a potential exists between the conductive line 310 and the user's finger, a current passes from the conductive line 310 to the ground through the finger. As a result, there is a potential difference between the conductive line 310 that serves as an input to the differential amplifier 340 and the pair 320.

  A description will now be given with reference to FIG. 3 showing the arrangement of the conductive lines of the digitizer sensor as an input to the differential amplifier according to the embodiment of the present invention. Since the separation between the two conductors 310 and 320 is generally greater than the width of the finger, the required potential difference can be formed, for example, about 12 mm or 8 mm to 30 mm. The differential amplifier 340 amplifies the potential difference that occurs between the conductive lines 310 and 320, and the ASIC 16 works with the digital unit 20 to process the amplified signal, thereby based on the amplitude and / or signal level of the sensed signal. Determine the position of the user's finger. In one embodiment, the position of the user's finger is determined by examining the phase of the output. In another embodiment, a finger touch typically produces an output on more than one conductive line, so the position of the user's finger is determined by examining the output of the adjacent amplifier. In still other embodiments, a combination of both methods can be realized. In some embodiments, the digital processing unit 20 operates to control the AC signal provided to the conductive lines of the sensor 12, such as the conductive lines 310 and 320. In general, a fingertip touch on a sensor may span 2-8 lines, for example 6 conductive lines and / or 4 differential amplifier outputs. In general, since a finger is placed on a plurality of conductive lines, an output signal is generated in two or more differential amplifiers, for example, a plurality of differential amplifiers. However, fingertip touch can be detected when placed on two or more conductive lines.

  Reference is now made to FIG. 4 schematically illustrating a capacitive touch method for fingertip touch detection using a digitizer sensor, according to some embodiments of the present invention. At each contact of sensor 12, for example contact 40, there is a certain minimum amount of capacitance between orthogonal conductive lines. In the exemplary embodiment, AC signal 60 is applied to one or more parallel conductive lines of two-dimensional sensor matrix 12. When the finger 41 touches the sensor at a specific position where the signal 60 is induced, at least close to the touch position, the capacitance between the conductive line to which the signal 60 is applied and the corresponding orthogonal conductive line increases, and the finger Thanks to the capacitance of 41, the signal 60 crosses the corresponding orthogonal conductive line and produces an output signal 65. This method can detect two or more finger touches (multi-touch) at the same time. This method can further calculate the touch area. In an exemplary embodiment of the invention, each conductive line is input to an amplifier. Optionally, each line is input to a differential amplifier while the other input of the amplifier is grounded. In general, when a finger is present, the finger typically drains current from the line, thus reducing the combined signal by 20-30%.

  The present invention is not limited to the technical description of the digitizer system described herein. Digitizer systems used to detect stylus and / or fingertip positions include, for example, the digitizer systems described in the incorporated US Pat. Nos. 6,690,156, 20040095333, and / or 20040155871. It can be similar. The present invention can also be applied to other digitization systems known in the art depending on the system configuration.

  In some embodiments of the present invention, a signal amplitude pattern and a signal amplitude gradient pattern are detected and used to indicate that the signal input to the digitizer is a fingertip touch input and / or signal detection is a fingertip. Verify touch detection. Now, FIG. 5A showing an exemplary signal pattern of signal amplitude output from a differential amplifier obtained from a fingertip touch and an exemplary signal pattern of a signal amplitude gradient resulting from a fingertip touch, according to some embodiments of the present invention This will be described with reference to FIG. We are typical of fingertip touches, and therefore other detections on the digitizer that occur due to fingertip touch and, for example, a hand resting on the digitizer or mechanical switching between the digitizer and LCD. We found a signal pattern that can be distinguished from the signal.

  In FIG. 5A, a region 71 where the fingertip contacts the digitizer sensor induces a plurality of signals on the vertical and horizontal conductive lines of the digitizer sensor. The amplitude of the detection signal detected from the horizontal conductive line is represented by a bar 73, and the amplitude of the detection signal detected from the horizontal conductive line is represented by a bar 72. In some exemplary embodiments, signals are detected not only in the conductive line region 71 but also in adjacent conductive lines. In general, signals induced in adjacent conductive lines are generated due to mechanical changes in the sensor and LCD when the fingertip depresses the digitizer sensor and LCD screen. In some exemplary embodiments, only amplitudes above a predetermined level are considered.

  In FIG. 5B, the amplitude gradient of the gradient signal is defined as the absolute value of the difference in amplitude detected on two adjacent conductive lines. Optionally, the slope is divided by the distance between adjacent conductive lines. In some exemplary embodiments, only gradients above a predetermined level are considered. Other known methods for representing the slope of the signal may be implemented and used to verify fingertip touch.

  In general, a fingertip touch can be characterized by a relatively high signal amplitude in the center portion of the detected touch area, which gradually decreases toward the peripheral area. In general, the gradient value can be expected to be relatively high near the area around the detected touch. When using a digitizer system in which conductive wire pairs are input to a differential amplifier, both inputs are made because the conductive wire pairs input to the same differential amplifier are touched simultaneously and / or during the same touch event. May be reduced evenly by touch, so that signal detection may produce approximately zero detection and / or “null” output. A “null” output results in either a substantially zero output signal and / or a relatively low output signal. This generally occurs with a hand touch that spans a relatively large area, but may also occur during a fingertip touch. Embodiments of the present invention differentiate between large area touches, such as hand touches, and fingertip touches, taking into account the expected frequency of approximately zero detection. In embodiments of the present invention, fingertip touch detection and / or verification is determined based on amplitude and gradient variations of the digitizer sensor output.

  Reference is now made to FIG. 6, which shows a flowchart of a method for verifying that a signal input to a digitizer is a signal input derived from a fingertip touch, in accordance with an exemplary embodiment of the present invention. In some embodiments of the present invention, the sensor conductive lines are interrogated to detect a signal on at least one of the sensor conductive lines (block 610). In the exemplary embodiment, both vertical and horizontal conductive lines are interrogated. In other exemplary embodiments, the conductive lines are interrogated in one of the two directions, eg, the horizontal direction and / or the direction in which the maximum number of conductive lines are expected to be affected. Alternatively, the query is made in the direction in which the minimum number of conductive lines are expected to be affected. Fingertip verification is achieved when it is determined that at least one conductive line has a signal amplitude that is higher than a predetermined event threshold (block 620). In one exemplary embodiment, fingertip verification is achieved when it is determined that at least one conductive line in each of the horizontal and vertical directions is higher than a predetermined event threshold. In another exemplary embodiment, fingertip verification is achieved when it is determined that at least one conductive line in either the horizontal and vertical directions is above a predetermined event threshold. In yet another exemplary embodiment, fingertip verification is achieved when it is determined that at least one conductive line in a particular direction is higher than a predetermined event threshold. In some exemplary embodiments, fingertip verification is achieved when it is determined that at least one conductive line on each axis is above a predetermined event threshold. In some exemplary embodiments, the default event threshold is the same in both directions. In other exemplary embodiments, the default event threshold is different in each direction.

  A pattern and / or distribution of signal amplitude detected on a conductive line in the vicinity of at least one conductive line that conveys a signal above a predetermined event threshold is determined and optionally stored (block 630). In some exemplary embodiments, the number of distribution lines inspected is limited by a predetermined number of lines on either side of at least one line that conveys a signal above a predetermined event threshold. . In other exemplary embodiments, all conductive lines are included in the determined distribution. In some embodiments of the invention, all conductive lines are inspected in groups using movable or peristaltic windows. For example, four conductive lines are inspected, and then another four conductive lines including one new conductive line adjacent to these three in addition to the three conductive lines from the first group. Inspected, etc. In one exemplary embodiment, all conductive lines of the sensor are scanned and / or queried on each axis, and when detecting an output above a threshold, eg, amplifier output, the next few amplifier outputs are also examined. Is done. In one embodiment, the following three outputs are examined:

  A slope measurement of the signal amplitude distribution is determined and optionally stored (block 640). The determined amplitude value below the predetermined amplitude threshold is set to a zero value (block 650). In general, the predetermined amplitude threshold of block 650 is lower than the event threshold of block 620. Decision slope values below the predetermined slope threshold are set to a zero value (block 660). In one exemplary embodiment, the amplitude threshold is a value equal to the slope threshold. In some embodiments of the invention, the resulting signal pattern is used to verify that the detected touch event is a fingertip touch event.

  In some exemplary embodiments of the invention, a group of conductive lines is inspected each time, eg, each time output from a differential amplifier (block 670). If a predetermined number of conductive lines in the group, eg, one of the four conductive lines, has a zero amplitude (eg, below some threshold) (block 680), the detected pattern is determined not to be a fingertip pattern (Block 690). Detected if a predetermined number of conductive lines in the group of gradient measurements, eg, three or more of the four conductive lines, have an amplitude close to zero (block 695). The determined pattern is not a fingertip pattern (block 690). A fingertip touch pattern is detected if the lines less than the predetermined number of lines have zero amplitude (block 698). After inspecting the first set of conductive lines, subsequent sets of conductive lines are inspected, for example, by replacing one conductive line and / or changing the size of the group being inspected. This process continues, for example, until a fingertip touch is detected, until no signal is detected in the set, or until all conductive lines have been inspected. In some embodiments of the present invention, both the amplitude pattern and the gradient pattern are examined, and the defined conditions are required to verify fingertip touch. In other embodiments of the invention, either the amplitude pattern or the gradient pattern is examined and used to verify the fingertip touch. Other methods of examining the distribution of signal amplitude and signal amplitude gradient can be used to determine whether an input signal is obtained from a fingertip touch.

  Here, FIG. 7A shows an exemplary fingertip signal pattern showing an amplitude value pattern higher than the amplitude threshold, and an amplitude value gradient pattern when the gradient is higher than the gradient threshold, according to some embodiments of the present invention. Reference is made to FIG. 7B, which shows an exemplary fingertip signal pattern showing. 7A and 7B correspond to the default threshold values shown in FIGS. 5A and 5B. In FIG. 7A, it is apparent from the signal detected in region 71 that the four continuous conductive lines 77 carry a signal above the amplitude threshold in the vertical direction and the four non-continuous conductive lines. It has been found that 76 conveys a signal that is above the amplitude threshold in the horizontal direction. In the horizontal direction, there was one conductive line with zero reading between the four conductive lines that were found to carry signals above the amplitude threshold. Thus, in some embodiments of the present invention, the amplitude pattern shown in FIG. 7A meets the fingertip touch requirement.

  In the exemplary pattern of FIG. 7B, it is apparent from the signal detected in region 71 that the four continuous conductive lines 79 carry a gradient signal above the gradient threshold in the vertical direction, and three It has been found that the discontinuous conductive line 78 carries a signal above the slope threshold in the horizontal direction. In the horizontal direction, there was a space of two conductive lines with zero reading between the three conductive lines that were found to carry signals above the slope threshold. Since only two spaces were found in the gradient pattern, the pattern shown in FIG. 7B satisfies the fingertip touch requirement. In some embodiments of the present invention, the pattern shown in FIG. 7A is used as a verification that the input signal 71 is a fingertip touch input signal along with the pattern shown in FIG. 7B. Since only a small window is examined each time, for example a window containing output from four adjacent parallel lines, the method described above can be used to detect one or more simultaneous finger touches. it can. The patterns shown in FIGS. 5A, 5B, 7A, and 7B are merely exemplary patterns, and other patterns that use other defined limits on the number of intervals between signal readings can be used to verify fingertip touch. May meet the requirements.

  Here, according to an embodiment of the present invention, signal amplitude, signal amplitude gradient, signal amplitude whose amplitude is higher than a predetermined amplitude threshold, and exemplary signal pattern of hand touch of signal amplitude gradient whose gradient amplitude is higher than a predetermined gradient threshold Will be described with reference to FIGS. 8A, 8B, 8C, and 8D, respectively. In an embodiment of the present invention, the hand input signal 81 induces a pattern and / or distribution of signal amplitude in the vertical direction 83 and the horizontal direction 82. In some exemplary embodiments, the signal is detected not only on the conductive lines in region 81 but also on adjacent conductive lines. In general, signals induced on adjacent conductive lines are generated due to mechanical changes in the sensor and LCD when the fingertip depresses the digitizer sensor and LCD screen.

  In general, the area affected by hand touch is larger than the area affected by fingertip touch and thus more “null” output of the differential amplifier may occur. In fact, the difference is usually much larger than shown in FIGS. In addition, in the hand touch, the contact is emphasized in the peripheral region of the hand, but in the fingertip touch, the contact is concentrated on the central portion of the finger and / or distributed evenly. Thus, one or more conductive lines corresponding to region 81 may read a relatively low value and / or a zero value. In some exemplary embodiments, relatively low and / or zero value readings occur because the output is a differential amplifier output and the signals at the differential inputs are approximately the same.

  This relative uniformity of the signal is also reflected in the gradient patterns 84 and 85 of the detection signal, which show low and / or zero gradient values corresponding to the gradient corresponding to the center of region 81. When considering FIGS. 8C and 8D, the zero reading corresponding to the center of region 81 is clearly shown in the horizontal direction, eg, signals 86 and 88, but in the vertical direction, eg, signals 87 and 89, Not really. In other embodiments, the reverse may be true. The method described herein and in FIG. 6 is due to the spacing between the signal values shown in FIGS. 8C and 8D, for example, two or more spaces at amplitude values higher than the amplitude threshold (FIG. 8C), and higher than the gradient threshold. Due to more than two spaces in the gradient value (FIG. 8D), the patterns displayed in FIGS. 8A-8D are rejected as non-fingertip touch patterns. Generally, when a signal is rejected, “no touch” data is reported to the host computer. In some embodiments of the invention, the methods described herein are used for palm rejection. The need for palm rejection is the convenience of placing the user's hand on the sensor (and not intended to interpret this type of touch as user interaction during the use of the stylus and / or finger) (and Due to ease).

  The methods described hereinabove can be applied to various types of digitizer sensors, such as the digitizer sensors described in both FIGS. 2 and 4 of the present invention. In an exemplary embodiment, when applying the digitizer sensor described in FIG. 4 such that each conductive line is associated and / or connected to a single amplifier, an amplitude pattern, such as the amplitude pattern shown in FIG. Thus, the number of spaces allowed before rejecting the input signal can be reduced, for example to zero. Thus, the detection of zero occurring in the space between adjacent amplitude readings and / or in the window being examined corresponds to the region detected as a non-fingertip touch input. In a system in which the differential signal is determined (eg as described in FIG. 2), both conductors of the differential amplifier are included in the induction region, eg to take into account the case where a zero detection occurs. Is allowed by a threshold amount. For systems that do not record differential signals between conductive lines, this consideration is not relevant.

  Reference is now made to FIG. 9 showing an exemplary flowchart describing a method for verifying that a signal input to a digitizer is a fingertip touch input signal, according to an exemplary embodiment of the present invention. In general, the method described in connection with FIG. 9 is used in conjunction with the touch detection method described in connection with FIG. In some embodiments of the present invention, the shape of the signal input area is estimated and considered when the signal detection corresponds to a fingertip touch. In some embodiments of the invention, the presence of a touch event is identified by detecting at least one conductive line having a signal reading with an absolute amplitude greater than a predetermined event threshold level (block 910). . The amplitude value of the signal detected on the sensor conductive line is determined (block 920). In some exemplary embodiments, the pattern of amplitude values is determined in an area defined around a conductive line that has a signal reading above the event threshold. In another exemplary embodiment, all conductive lines are queried to determine the amplitude value pattern. In some embodiments of the invention, amplitude values below a predetermined amplitude threshold are set to zero detection.

In some embodiments of the invention, a ratio is determined between the number of conductive lines found on each of the orthogonal axes that have a detection signal above a predetermined amplitude threshold (block 930). In one exemplary embodiment, a shape scale is determined, which is the ratio of the number of conductive lines on the long axis to the number of detection lines on the short axis of the touch area. A query is made to determine if the ratio is within a predetermined range (block 940). In some exemplary embodiments, finger touch input corresponds to a ratio of about 1: 1 or 2: 1. Optionally, signals corresponding to ratios outside this range are rejected as non-finger patterns. In some embodiments of the invention, the region of the input signal is determined (block 960). In one exemplary embodiment, the area of the input signal is approximated as a rectangle and is determined based on the length of the input signal in each of the orthogonal axes of the sensor. The length is approximated, for example, by multiplying the number of conductive lines that contain a detection signal above the amplitude threshold by the spacing between the conductive lines. A query is made to determine whether the calculated area is within a specified range corresponding to a fingertip touch (block 970). In some embodiments of the invention, a detection area in the range of about 16 mm ² to 500 mm ² is considered as a range corresponding to a fingertip touch. Detection ranges outside this defined range are rejected as non-fingertip signals (block 950). In one exemplary embodiment, the region determination is performed prior to the ratio determination. In another exemplary embodiment, either one of them is realized as opposed to both a ratio determination and / or a region determination. In some embodiments of the invention, a query is made to determine a window of the examination area that includes space (block 980). If a window with no space is found, the detected signal meets the requirements defined as a fingertip signal, otherwise the signal is rejected. A gradient pattern is determined (block 985). The slope value is the difference between signal amplitudes detected on adjacent and / or neighboring conductive lines. In one exemplary embodiment, for example, for a grid of conductive lines that are not evenly spaced, the determined slope value is divided by the distance between adjacent conductive lines. In some exemplary embodiments, only gradient values above the gradient threshold are considered, and other gradient values are set to zero. Optionally, the slope threshold and the amplitude threshold have the same value. The number N of conductive lines from which signals are detected is determined. If more than N-2 spaces are determined in the gradient signal, the input signal is rejected (block 990). In general, when examining a gradient image, the signal is detected at the edge, for example at the contour of the image, and thus uses N-2 space. Otherwise, the input signal is verified and accepted as a fingertip input signal (block 995). In other embodiments of the invention, one or more blocks can be omitted and / or the order of the blocks can be rearranged.

  In some embodiments of the present invention, a spatial high pass filter is used to determine the gradient pattern of the input signal. Since the spatial high-pass filter passes only a high-frequency signal, a region where the change in the signal amplitude is large is detected. In general, these areas correspond to the edges of the finger touch detection area, and therefore, contour variations with relatively large variations are obtained from the output of the high pass filter.

  The sensitivity of the method described herein for verifying that the signal detected by the digitizer sensor is a fingertip touch depends on several parameters, and the parameters and their thresholds vary depending on the application. Various parameters include signal amplitude threshold and “touch event” threshold, signal amplitude gradient threshold, specified range of ratio between signals detected on the sensor's orthogonal conductive lines, specified range of input signal, high range The cut-off frequency of the pass filter, as well as the number of antennas being examined. One or more of the parameters described to verify that the signal detected by the digitizer sensor corresponds to a fingertip touch can be used in combination with other parameters or alone.

  In some embodiments of the invention, the methods described herein can be used to distinguish stylus input, fingertip input, and other user input. In some embodiments of the invention, some of the methods described herein may be performed by the host computer 22, the digital unit 20, and / or the ASIC unit 16.

  As used herein, the term “pattern” does not refer to just a region on a digitizer sensor where a signal is detected.

  It should be further understood that the individual features described hereinabove can be combined in any possible combinations and subcombinations to produce exemplary embodiments of the invention. Furthermore, not all elements described for each embodiment are essential. In many cases, such elements are described to describe the best mode for carrying out the invention or to form a logical bridge between the essential elements. The embodiments listed above are exemplary in nature and are not intended to limit the scope of the invention, which is defined only by the appended claims.

  As used herein, the terms “including”, “comprising” and “having” and their conjuncts mean “including but not necessarily limited to”.

Claims (46)

  A method for verifying fingertip touch input to a digitizer, the step of detecting a pattern of a signal obtained from a conductive line of a digitizer sensor, the step of comparing the pattern with a predetermined fingertip characteristic, and the comparison Recognizing a fingertip touch input based on the method.   The method of claim 1, wherein the conductive lines are parallel conductive lines.   The method of claim 1 or 2, wherein the conductive lines comprise two orthogonal sets of parallel conductive lines forming a grid.   The method of claim 3, wherein the two orthogonal sets are electrically separated from each other.   The method according to claim 2, wherein the parallel conductive lines are arranged at equal intervals.   The method according to claim 2, wherein the parallel conductive lines are arranged at intervals of 4 mm.   7. A method as claimed in any of claims 2 to 6, wherein parallel conductive wire pairs are input to a differential amplifier.   The method of claim 7, wherein the pattern is a differential amplifier output pattern.   9. A method according to claim 7 or 8, wherein the pair of parallel conductive lines are non-adjacent conductive lines.   The method according to claim 1, wherein the pattern is a signal amplitude pattern.   The method according to claim 1, wherein the pattern is a signal amplitude pattern higher than a predetermined amplitude threshold.   The method according to claim 1, wherein the pattern is a signal amplitude gradient pattern.   The method according to claim 1, wherein the pattern is a signal amplitude gradient pattern higher than a predetermined gradient threshold.   14. A method according to any of claims 1 to 13, comprising determining the number of gaps in the signal pattern.   The method of claim 14, comprising determining a maximum number of gaps and satisfying the requirement that the pattern of signals verify fingertip touch with a lower number of gaps.   The method according to claim 1, wherein the pattern of signals is detected using a capacitive touch method.   17. A method according to any of claims 12 to 16, wherein the signal amplitude gradient is a spatial high-pass filter signal of the signal pattern.   The method of claim 17, wherein the pattern is a contour pattern.   19. A method according to any of claims 16 to 18, comprising the steps of determining a ratio of the size of the detected area by the digitizer sensor and defining a range of ratios that satisfies the requirement to verify fingertip touch.   20. The method of claim 19, comprising determining an area where a signal is detected on the digitizer sensor and determining a range of areas that satisfy a requirement to verify fingertip touch.   21. A method according to any preceding claim, wherein the digitizer sensor is transparent.   The method according to claim 1, wherein the detection includes multi-touch detection.   Validating a fingertip touch input to a digitizer comprising a digitizer sensor including a plurality of conductive lines and a controller operable to verify the fingertip touch input based on detection of a pattern of output from the plurality of conductive lines System for.   24. The system of claim 23, wherein the plurality of conductive lines includes parallel conductive lines.   25. A system according to claim 23 or 24, wherein the plurality of conductive lines comprises two orthogonal sets of parallel conductive lines forming a grid.   26. The system of claim 25, wherein the two orthogonal sets are electrically separated from each other.   27. A system according to any of claims 23 to 26, wherein the plurality of conductive lines are arranged at equal intervals.   The system according to any one of claims 23 to 27, wherein the plurality of conductive lines are arranged at intervals of 4 mm.   29. A system according to any of claims 23 to 28, wherein the parallel conductive wire pairs are input to a differential amplifier.   30. The system of claim 29, wherein the pattern is a differential amplifier output pattern.   31. A system according to claim 29 or 30, wherein the parallel conductive wire pairs are non-adjacent conductive wires.   32. A system according to any of claims 23-31, wherein the controller is operative to determine a pattern of signal amplitude from the output.   33. A system according to any of claims 23 to 32, wherein the controller is operative to determine a pattern of signal amplitude from an output above a predetermined amplitude threshold.   34. A system according to any of claims 23 to 33, wherein the controller is operative to determine a pattern of signal amplitude gradients from the output.   35. A system according to any of claims 23 to 34, wherein the controller is operative to determine a pattern of signal amplitude gradients from an output above a predetermined gradient threshold.   36. A system according to any of claims 23 to 35, wherein the controller is operative to determine the number of gaps in the signal pattern.   40. The system of claim 36, wherein the controller is operative to reject an input signal corresponding to a pattern having a gap above a predetermined maximum number of gaps.   38. A system according to any of claims 23-28, 32-37, wherein the pattern of output is detected using a capacitive touch method.   39. A system according to any of claims 34 to 38, wherein the signal amplitude gradient is an output high pass filter signal.   40. The system of claim 39, wherein the pattern is a contour pattern.   The controller is operative to determine a ratio of the size of the area in which the output was detected and to determine whether this ratio is within a predetermined ratio that satisfies the requirement to verify fingertip touch. 41. A system according to any of claims 38-40.   The controller determines whether the area is within a predetermined area that satisfies a requirement for verifying a fingertip touch, and the size is a predetermined size range that satisfies the requirement for verifying a fingertip touch. 42. The system of claim 41, operable to determine whether or not.   43. A system according to any of claims 23 to 42, wherein the digitizer sensor is transparent.   44. A system according to any of claims 23 to 43, wherein the controller is operative to detect a multi-touch input.   45. A system according to any of claims 23 to 44, comprising a host computer, the host computer communicating with a controller.   46. The system of claim 45, wherein the controller sends the verified input as a fingertip input to the host computer.

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