Patent application number | Description | Published |
20090115740 | INTERRUPT REDUCTION METHOD IN TOUCH SCREEN CONTROLLER - Integration of a FIFO memory, FIFO threshold and a timer, along with the other components of a touch screen system allows the number of interrupts to the touch screen controller to be reduced while allowing all point data to be acquired and preserved. In the first touch-detect event, an interrupt is issued to inform the host. The touch screen controller then automatically acquires data as long as touch is detected without host intervention. A FIFO threshold defines the minimum number of data points in FIFO memory before it issues an interrupt to inform the host that data is ready to be fetched. The timer is started once touch is detected. On every single data acquired, the timer is reset. In the event where touch is no longer detected, the timer keeps on counting until the time-up limit is reached. In this event, the touch screen controller will issue an interrupt informing the host the pen is lifted. The host then checks whether there is still data left in FIFO memory to be read. | 05-07-2009 |
20100051354 | CAPACITIVE TOUCH SENSOR SYSTEM - A method of matrix sensing using delay-based capacitance sensing, including using X-axis lines as active lines for capacitance measurements and using Y-axis lines as a disturbance to identify the location of a touch in a key matrix is disclosed. A sensing signal is applied to the X-axis lines, and a disturbance signal is applied to the Y-axis lines. If a location is touched, cross-capacitance is reduced, which is measured by sweeping data along the X-axis lines. | 03-04-2010 |
20100053097 | CAPACITIVE TOUCH SENSOR SYSTEM - A method of matrix sensing using delay-based capacitance sensing, including using X-axis lines as active lines for capacitance measurements and using Y-axis lines as a disturbance to identify the location of a touch in a key matrix is disclosed. A sensing signal is applied to the X-axis lines, and a disturbance signal is applied to the Y-axis lines. If a location is touched, cross-capacitance is reduced, which is measured by sweeping data along the X-axis lines. | 03-04-2010 |
20100066701 | MULTIPLE TOUCH LOCATION IN A THREE DIMENSIONAL TOUCH SCREEN SENSOR - A touch screen capable of correctly identifying multiple touches employs multiple active line arrays oriented to provide multi-dimensional data. Three arrays of capacitance based active lines are each distinctly oriented to form a plurality of intersections. A first and second array are generally oriented perpendicularly while a third array is oriented to bisect the resulting matrix such that the active lines of the third array also intersect the existing vertices. As a result of a touch each active line array identifies the location of the touch from three distinct directions. Ambiguity from dual touch scenarios existing in dual array systems is removed by providing an additional reference. | 03-18-2010 |
20100328249 | CAPACITIVE-INDUCTIVE TOUCH SCREEN - A touch screen uses a combination of capacitive sensing and inductive sensing applied to the same sensor pattern. A capacitive sensor uses the electric field formed by the columns and rows of the sensor matrix. An inductive sensor uses the magnetic field formed by current flowing in column and row lines to induce an inductive pen. Using the same sensor lines, the magnetic field created by the oscillating inductive pen is detected. Both methods require no moving elements in the sensor and it is possible to combine both method of detections in the same sensor pattern. Using switch matrices, the sensor lines are operated in an open loop fashion for the capacitive detection mode, and are operated in a closed loop fashion for the inductive detection mode. | 12-30-2010 |
20110242048 | CAPACITIVE SENSING ANALOG FRONT END - A capacitive sensing analog front end for a touchscreen system having an improved signal-to-noise ratio includes a capacitance-to-voltage converter having an input for coupling to an external sampling capacitor, a summer having a first input coupled to an output of the capacitance-to-voltage converter, a low pass filter having an input coupled to an output of the summer and an output for providing an output signal; and a sample-and-hold circuit having an input coupled to the output of the low pass filter and an output coupled to a second input of the summer. The signal-to-noise ratio of the touchscreen system is improved by extracting the DC shift of a touch signal during a monitoring period and then subtracting the DC shift before integrating the touch signal. | 10-06-2011 |
20110242052 | MULTIPLE TOUCH LOCATION IN A THREE DIMENSIONAL TOUCH SCREEN SENSOR - A touch screen capable of correctly identifying multiple touches employs multiple active line arrays oriented to provide multi-dimensional data. Three arrays of capacitance based active lines are each distinctly oriented to form a plurality of intersections. A first and second array are generally oriented perpendicularly while a third array is oriented to bisect the resulting matrix such that the active lines of the third array also intersect the existing vertices. As a result of a touch each active line array identifies the location of the touch from three distinct directions. Ambiguity from dual touch scenarios existing in dual array systems is removed by providing an additional reference. | 10-06-2011 |
20120001643 | SENSING PHASE SEQUENCE TO SUPPRESS SINGLE TONE NOISE - A noise suppression method for a capacitance-to-voltage converter varies a sequence of sensing signal edges during a plurality capacitance measurements to produce a number of noise responses. The sensing signal edges are varied in a repetitive rising and falling edge pattern for each sequence. Three or more such sequences can be used, and the sequence with the highest noise is eliminated and the others are averaged. The noise suppression method can be implemented during calibration and then used for a number of normal acquisitions. The noise suppression method can be applied to capacitance-to-voltage converters having monitoring and integration phases. | 01-05-2012 |
20120120001 | CHARGE AMPLIFIER FOR MULTI-TOUCH CAPACITIVE TOUCH-SCREEN - A circuit for measuring the cross-capacitance of a touch-screen sensor includes a charge amplifier having an input for coupling to the touch-screen sensor and an output for providing a voltage pulse, and a measurement delay chain having an input coupled to the output, and an output for providing a digitized output signal of the voltage pulse width, which is proportional to the value of the cross-capacitance. | 05-17-2012 |
20120161794 | SYNC SIGNAL GENERATOR FOR A CAPACITIVE SENSOR - A sync signal generator for a capacitive sensor includes a charge amplifier having an input for coupling to an inactive receive line in the capacitive sensor, a first comparator having a first input for receiving a first threshold voltage, a second input coupled to an output of the charge amplifier, and an output for providing a first sync signal, and a second comparator having a first input for receiving a second threshold voltage, a second input coupled to the output of the charge amplifier, and an output for providing a second sync signal. The charge amplifier includes an operational amplifier having a feedback circuit including a capacitor and a switch. The first threshold voltage is provided by a first digital-to-analog converter, and the second threshold voltage is provided by a second digital-to-analog converter. | 06-28-2012 |
20120161846 | CAPACITIVE TO VOLTAGE SENSING CIRCUIT - A circuit for converting a measured variable capacitance to an output voltage signal includes a charge amplifier circuit selectively coupled to an integrator circuit. The charge amplifier circuit, in one implementation, is configured as a high pass filter. In another implementation, the charge amplifier circuit is configured as a combination high pass and low pass filter. The charge amplifier circuit is selectively coupled to the integrator circuit when the circuit forces a switch in voltage across a measurement capacitor. | 06-28-2012 |
20120300140 | PATTERNED CONDUCTIVE LAYERS FOR SENSOR ASSEMBLY AND METHOD OF MAKING THE SAME - An ITO sensor design and method for making the same is optimized to minimize noise from an LCD. The design includes a two layer sensor design having a transmitter line (Tx) placed in a first layer and a receiver line (Rx) placed in a second layer in a diamond-shaped pattern. The diamond shape maximizes the sensitivity of the sensor. | 11-29-2012 |
20130063388 | CAPACITIVE TOUCH SCREEN CONTROLLER IMPLEMENTING A SENSING METHOD FOR IMPROVED NOISE IMMUNITY - A capacitive touch sensor includes horizontal lines vertical lines. Switching circuitry is coupled to the horizontal and vertical lines of the capacitive touch sensor. The switching circuitry is operable in a first mode to configure the horizontal lines as receive lines and the vertical lines as transmit lines for making a cross-capacitance measurement. In one implementation, the switching circuit is further operable in a second mode to configure the horizontal lines as transmit lines and the vertical lines as receive lines for making an additional cross-capacitance measurement. In another implementation, the switching circuit is further operable in a second mode to configure the vertical lines for making a self capacitance measurement. The various capacitance measurements from the first and second modes are algorithmically combined to obtain a total capacitance measurement having a reduced noise component. | 03-14-2013 |
20140035602 | ITO PATTERN FOR CAPACITIVE TOUCHSCREEN APPLICATIONS - A capacitive sensing structure is formed from first electrically conductive sensor structures electrically coupled to each other in a first direction, and second electrically conductive sensor structures electrically coupled to each other in a second direction. Each first electrically conductive sensor structure includes a first diamond-shaped central region with electrically coupled first finger structures extending away therefrom. Each second electrically conductive sensor structure includes a second diamond-shaped central region with electrically conducting second finger structures extending away therefrom. Each second finger structure extends between two adjacent ones of the first finger structures. Floating structures may be included within an opening formed in the first diamond shaped central region. Floating structures may further be included between the first and second finger structures. | 02-06-2014 |
20140049501 | SENSELINE DATA ADJUSTMENT METHOD, CIRCUIT, AND SYSTEM TO REDUCE THE DETECTION OF FALSE TOUCHES IN A TOUCH SCREEN - A touch controller processes a captured data frame and detects the presence of touch points in the data frame. The data frame includes a plurality of digital capacitance values organized as groups of sense line data and the touch controller determines for each digital capacitance value in a group of sense line data the difference between the digital capacitance value and an associated no-touch threshold to generate a baseline delta value for each digital capacitance value in the group. The touch controller selects the minimum baseline delta and adjusts each digital capacitance value in the group by the minimum baseline delta to generate adjusted sense line data. The touch control generates adjusted sense line data for each group of sense line data in the data frame and thereafter processes the groups of adjusted sense line data to detect the presence of touch points in the data frame. | 02-20-2014 |
20140306921 | MULTIPLE ROW RECEIVING LINE PATTERN FOR IN-CELL TOUCHSCREEN PANELS - An in-cell touchscreen panel includes columns of transmit electrodes and rows of sensing electrodes, wherein each row of sensing electrodes comprises a first subset of sensing electrodes coupled to control circuitry via a first subset of receiving traces and a second subset of sensing electrodes coupled to the control circuitry via a second subset of receiving traces. To enable multi-touch functionality, the in-cell touchscreen panel operates in a scanning mode where capacitance is measured at each node where the sensing electrodes intersect the transmit electrodes. During the scanning mode, the control circuitry senses the first and second subsets of receiving traces while applying drive signals to pairs of transmit electrodes. After a drive signal has been applied to each of the transmit electrodes, each of the nodes are measured to detect a capacitance. This capacitance is indicative of a user touch on the in-cell touchscreen panel. | 10-16-2014 |
20140307840 | DIGITAL IIR FILTER WITH ADJUSTABLE FILTER WEIGHTS BASED ON MEASURED CHANGES IN THE PROCESSED DATA - A digital filter receives a sequence of input signal values. A filtering block performs a filtering operation on sequence of input signal values that is controlled by filter coefficients. A control block also receives the sequence of input signal values. The control block evaluates detected changes over time with respect to the sequence of input signal values and selects values for the filter coefficients based on the detected changes. The detected change over time provides an indication of the whether the sequence of input signal values is changing signal state. If so, the filter coefficients are selected to emphasize signal response time over signal noise filtering for the filtering operation. Otherwise, the filter coefficients are selected to emphasize signal noise filtering over signal response time for the filtering operation. | 10-16-2014 |