Patent Application
20140057681
Various embodiments disclosed herein concern touch-screen or touch-panel displays, particularly controllers for such displays.
In recent years, touch-screen displays—that is, electronic displays that sense the touch of a finger or stylus—have become relatively common in many types of electronic devices. The devices range from retail payment terminals to automatic teller machines to tablet computers to mobile telephones. One key reason for their prevalence is their intuitive ease of use.
In general, a touch-screen display works by sensing a touch on a glass pane and then communicating the location of the touch to a processor inside the host electronic device. Although the processor interprets the touch based on the information displayed at the touch location, the success of the interpretation depends ultimately on a component, called a touch-screen controller, which determines not only whether a touch event has occurred, but also its precise location.
One problem with conventional touch-screen controllers, particularly those in mobile telephones, is that they are prone to erratic behavior when the mobile telephone is plugged into devices, such as AC power adapters. The power adapters generate electrical noise that sometimes mimics or obscures actual touch events, thus making it difficult for the controllers to determine correctly if and where a touch has actually occurred.
Conventionally, this noise problem as been addressed by raising the drive and threshold voltages in the touch-screen display to fixed higher values, thereby reducing the likelihood that lower voltage noise variations will interfere with proper operation. This solution, analogous to constantly yelling over the noise in a crowded restaurant to be heard, is highly effective. However, it also suffers from two significant disadvantages.
First, it increases power consumption by the touch-screen display and thus reduces the battery life of the mobile telephone or other device using it. Second, operating the touch-screen display at a higher voltage also causes the display to generate its own noise that can interfere with other circuitry, for example, WiFi, cellular, GPS, and Bluetooth radio receivers in a host device, effectively reducing their sensitivity to incoming signals.
The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, together with the detailed description below, are incorporated in and form part of the specification, and serve to further illustrate embodiments of concepts that include the claimed invention, and explain various principles and advantages of those embodiments.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
This document, which incorporates the drawings and the appended claims, describes one or more specific embodiments of one or more inventions. These embodiments, offered not to limit but only to exemplify and teach the invention, are shown and described in sufficient detail to enable those skilled in the art to implement or practice the invention(s). Thus, where appropriate to avoid obscuring the invention(s), the description may omit certain information known to those of skill in the art.
In general, the present inventors devised, among other things, one or more example systems, methods, software, and related components that provide more effective handling of noise in touch-screen controllers. One example system includes a touch-screen controller that measures noise level in capacitive touch-screen circuitry and iteratively increases and decreases the drive voltage as necessary to exceed the measured noise level and achieve desired noise margins relative to the measured noise, thereby reducing the chance of noise signals being misinterpreted as touch events while also reducing power consumption. Moreover, for embodiments that include radio receivers, intelligently adapting the touch-screen voltages based on measured noise, avoids the sensitivity-reduction (desense) issues that providing constant higher operating voltage creates.
Electronic device 100 includes a processor module 110 electrically coupled to a radio bank 120, a memory module 130, input/output devices 140, a power module 150, display 160, a capacitive touch screen 170, and a touch screen controller 180.
Radio bank 120 includes one or more wireless transceivers and corresponding baseband processors. The example embodiment includes a WLAN (wireless local area network) radio and baseband processor module 122, a GSM radio and baseband processor module 124, and other radio module 126. Other radio module includes additional radio modules, such as Bluetooth piconet, WiFi, (Wireless Fidelity), GPS (Global Positioning System), LTE (Long Term Evolution), and UMTS (Universal Mobile Telecommunications System) radio receivers and/or transceiver modules with corresponding processing circuitry.
Memory module 130 stores an operating system, one or more application programs, and associated data. In the example embodiment, memory module 130 takes the form of one or more electronic, magnetic, or optical data-storage devices.
Input-Output devices 140 includes various keyboards, pointing devices, joy sticks and ports or sockets for connection to peripheral devices, such as HDMI (High Definition Multimedia Interface) and USB (Universal Serial Bus) compliant devices.
Power module 150 includes components and circuitry for providing power to system 100. In the example embodiment, module 150 includes a power supply, one or more batteries, battery-charging circuitry, and an AC adapter; module and plug.
Display 160 takes any conventional form of display technology. For example, some embodiments provide a liquid crystal display, others may include light emitting diodes (LED) or AMOLED or super-AMOLED displays.
Capacitive touch screen 170 cooperates with display 160 and touch screen controller 180 to provide a single or multi-touch input capability for system 100.
More specifically, touch screen controller 180 includes a processor module 181, a memory 182, an adjustable voltage regulator 183, a drive control circuit 184, a multiplexer 185, and an analog-to-digital converter (ADC) 186.
Processor module 181, for example a digital signal processor or microcontroller, operates according to machine readable instructions and data stored within memory 182, which is shown as on-board memory. However, in some embodiments, memory 182 is wholly or partly contained in one or more separate components.
Memory 182 includes a noise mitigation (NM) module 1821, which includes instructions for generally causing processor module 182 to continually or based on events, such as an AC adapter, USB or HDMI plug-in event, measure noise floor level exhibited by touch screen circuitry 170 and to adjust the drive and threshold voltages for the touch screen circuitry to a predetermined level above the measured noise floor, for example 5, 10, 15, 20, 25, 30, or 25%, thereby adaptively mitigating impact of the noise on touch screen performance while reducing impact of the mitigation on battery life and radio sensitivities. In some embodiments, the predetermined amount is a function of other operational or environmental parameters, such as whether an AC adapter or USB connection is present. See below for further details.
Adjustable voltage regulator 183, which takes an analog or digital form, is responsive to control signals from processor module 181 per direction of noise mitigation module 1821, to provide a regulated voltage signal to drive control circuit 184.
Adjustable voltage regulator circuit 183A, in
Drive control circuit 184 receives the voltage from voltage regulator 183 (regardless of its particular form or implementation) and controls the transmission (TX) line drive supply for touch-screen display 170 via multiplexer 185. Analog-to-digital converter 186 converts voltage signals from the touch screen display 170 to a digital signal for use by processor 181, for noise-mitigation processing as well as for conventional touch-screen processing for providing touch data to processor 110.
More particularly,
At block 310, the example method begins with activation of electronic device 100. In particularly, this would entail activating system 100 in such as way that touch screen display is activated. Execution continues at block 320.
Block 320 entails calibrating the touch-screen display. In the illustrative embodiment, this calibration entails taking numerous measurements of the electronic device 100 to establish a baseline or expected value of one or more parameters, including the background capacitance on each channel. Other methods for calibration would be acceptable, all with the purpose of properly preparing the system to perform precise measurements of both signal (touches) and noise. Execution continues at block 330.
Block 330 entails determining whether noise level on the touch screen panel circuitry is outside an acceptable range. In the illustrative embodiment, this entails first measuring the noise level by taking a measurement of touch screen panel sensor outputs in the presence of no excitation from the transmitters. Noise can also be measured by examining the normal measurements for high frequency variation from measurement to measurement and across the sets of measurements. The measured noise level is then compared to an acceptable predetermined range which sets a minimum level for signal-to-noise ratio (SNR) performance depending on the system requirements. In some embodiments, the SNR is a fixed level or a level based on past signal data to maintain a desired level of performance (such as sensing no false touches upon the display surface). If the controller determines that the noise level is outside the acceptable range, the execution of the process branches to block 340 and if it is acceptable, execution branches to block 350.
Block 340 entails raising voltage levels in the touch-screen display and adjusting the receiver sensitivity appropriately to match. In the illustrative embodiment, this entails processor 181 issuing some form of command, either a digital communication signal or analog control voltage to the variable adjustable regulator 183 to increase its drive voltage by a predetermined amount, for example 0.5 Volts. It also entails attenuating the receiver input by a corresponding amount. In some implementations, this attenuation (more generally an adaptation or adjustment) is achieved in the analog domain; however, other embodiments make it in the digital domain or in both the analog and digital domains. In some embodiments, the incremental adjustment level is a function of whether or not, the system has detected a plug-in condition, such as when an AC adapter, HDMI, or USB connector has been plugged into the electronic device. In these instances, a more aggressive mitigation protocol, 10, 20, 30, 40, . . . , 100% greater than what would be employed in non-plug-in states may be warranted. Also, in some embodiments, the mitigation protocol is a function of the battery level of the system, enabling responsive mitigation with reduced battery drain.
Block 350, which is executed in response to determining that the noise level is acceptable at block 330, entails measuring touch-screen signal strength. In the illustrative embodiment, the signal strength is measured by sampling and/or averaging one or more touch-screen sensor readings. Execution continues at block 360.
Block 360 entails determining whether the signal strength margin is excessively high. In the example embodiment, this entails comparing the touch-screen signal strength to a minimum acceptable threshold for proper operation, and determining whether the signal strength is greater than that threshold by at least a given value or percentage, for example 10%. (For the sake of radio receiver sensitivity, the illustrative embodiment is designed to look for opportunities to reduce the signal strength while still allowing for proper operation.) If the determination is that the signal strength is not excessive, execution returns to block 330, and if the determination is that it is excessive, execution continues at block 370.
Block 370 entails lowering voltage levels in the touch-screen display and adjusting the touch-screen processor receiver sensitivity appropriately to match. In the illustrative embodiment, this entails processor 181 issuing some form of command, either a digital communication signal or analog control voltage to the variable adjustable regulator 183 to decrease its drive voltage by a predetermined amount, for example 0.5 Volts. It also entails increasing the receiver input by a corresponding amount. In some embodiments, the incremental adjustment level is a function of whether or not, the system has detected a plug-in condition, such as an AC adapter, HDMI, or USB connector being plugged in. Also, in some embodiments, the downgrade slope is a function of the battery level of the system, with higher battery level resulting in a more gradual decrease and lower battery level resulting in more rapid decrease. Execution returns to block 320.
In the foregoing specification, specific embodiments have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present teachings.
The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.
Moreover in this document, relational terms, such as second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” “has”, “having,” “includes”, “including,” “contains”, “containing” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, has, includes, contains a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “comprises a”, “has . . . a”, “includes . . . a”, “contains . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises, has, includes, contains the element. The terms “a” and “an” are defined as one or more unless explicitly stated otherwise herein. The terms “substantially”, “essentially”, “approximately”, “about” or any other version thereof, are defined as being close to as understood by one of ordinary skill in the art, and in one non-limiting embodiment the term is defined to be within 10%, in another embodiment within 5%, in another embodiment within 1% and in another embodiment within 0.5%. The term “coupled” as used herein is defined as connected, although not necessarily directly and not necessarily mechanically. A device or structure that is “configured” in a certain way is configured in at least that way, but may also be configured in ways that are not listed.
It will be appreciated that some embodiments may comprise one or more generic or specialized processors (or “processing devices”) such as microprocessors, digital signal processors, customized processors and field programmable gate arrays (FPGAs) and unique stored program instructions (including both software and firmware) that control the one or more processors to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used.
Moreover, some embodiments can be implemented as a computer-readable storage medium (more generally a non-transient storage medium) having computer readable code stored thereon for programming a computer (e.g., comprising a processor) to perform a method as described and claimed herein. Likewise, computer-readable storage medium can comprise a non-transitory machine readable storage device, having stored thereon a computer program that include a plurality of code sections for performing operations, steps or a set of instructions.
Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, a CD-ROM, an optical storage device, a magnetic storage device, a ROM (Read Only Memory), a PROM (Programmable Read Only Memory), an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory) and a Flash memory. Further, it is expected that one of ordinary skill, notwithstanding possibly significant effort and many design choices motivated by, for example, available time, current technology, and economic considerations, when guided by the concepts and principles disclosed herein will be readily capable of generating such software instructions and programs and ICs with minimal experimentation.
The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various embodiments for the purpose of streamlining the disclosure. This method of disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed embodiment. Thus the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter.
