Patent Application
20110285660
The disclosed embodiments relate generally to touch screens and more particularly to power generation in electronic devices having a touch screen.
As electronic devices become increasingly prevalent in our daily lives, it is important to improve the ease with which users may interact with these devices. The “touch screen” is one way in which users can interact with various electronic devices, such as wireless mobile communication devices. For example, by simply touching the touch screen of a wireless mobile communication device with a finger or a stylus, a user can easily perform a number of tasks (e.g., navigating menus, making selections, configuring applications, etc.).
A power-generating touch screen converts a force applied to a touch screen of an electronic device into an electric charge capable of powering a logical circuit of the electronic device. In various embodiments, the touch screen comprises one or more piezoelectric transducer array layers that convert the force into electrical charges. The converted electrical charges are collected in a capacitor array layer, which is discharged in order to power logical circuits of the electronic device or to charge a battery of the electronic device.
The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments. In addition, references to “an,” “one,” “other,” “another,” “the,” “this,” “alternative,” “some,” or “various” embodiments should not be construed as limiting since various aspects of the disclosed embodiments may be used interchangeably within other embodiments.
Turning now to
For the example of
The PET elements may be arranged in any configuration, including an array that forms each PETA layer. Referring briefly to
Although other arrangements may be used in some circumstances, the PETs are packed and arranged such that the pressure produced (e.g., force applied) when a user touches the screen is used to fire as many PETs as possible within the area upon which the force from the touch is being imparted. Moreover, the small size of the PETs ensures that the PETA layers are practically transparent, allowing a user to clearly see any other layers of the touch screen 100 that may be positioned beneath the PETA layers 102.
When force from a user touch is imparted onto the PETs of the PETA layers 102, each PET that experiences the force generates a small electric charge (e.g., converts the force into an electrical charge). In accordance with the exemplary embodiment, the electric charges are to charge the capacitor array layer 104, which is coupled to the PETA layers 102. The capacitor array layer 104 includes a plurality of capacitors in the example shown. Although a single capacitor array layer 104 is discussed herein, multiple capacitor array layers may be used in some circumstances. As discussed with reference to
The connection of the capacitors 206 in parallel allows the charges to be evenly distributed over the capacitors 206 of the capacitor array layer 204. In some circumstances, the capacitors 206 have a high voltage rating. Examples of suitable types of capacitors include high capacity electrolytic capacitors. The capacitor array layer 204 may be replaced by any device or structure capable of receiving a charge from the PETA layer 200 and storing the charge. One example of such a device includes a battery. Similarly, the PETA layer 200 could be replaced by any device or structure capable of transforming force from a user touch into electrical charge.
Where a PETA layer is used, the charge developed by the PETA layer can be given by:
Q=d×P×A
eff (Equation 1)
‘Q’ is the charge accumulated in Coulombs.
‘P’ is the pressure applied in Pascals.
‘d’ is the piezoelectric constant relating the mechanical strain produced by an applied electric field (meter/volt).
‘Aeff’ is the effective area that experiences pressure in m2.
Also, where multiple stacks of the PETA layer are used, the charge is multiplied by the number of PETA layers used.
Taking the piezoelectric transducers' capacitance into consideration, the voltage developed is,
V=(d×P×Aeff)/(CP) (Equation 2)
The Energy generated can be given by,
E=(CP×((d×P×Aeff)/(CP))2)/2 (Equation 3)
‘d’ for a widely used Piezoelectric material—Poly Vinylidene Flouride (“PVDF”)—is 23×10−12 m/V, considering one dimensional stress. Pressure due to the finger can be assumed at around 1 kPa. The ‘Aeff’ can be approximated to be 1 cm2, considering a single finger. The Cp in the case of PVDF is 1.36 nF.
Thus, the voltage generated by a single PETA layer is ˜2.3 mV for a particular example. Where a large number of PETA layers are used, the voltage generated will be much higher and result in a more easily usable amount of energy. An example of a large number is ten thousand PETA layers.
For the example referred to with reference to
The touch screen 100 also includes a display layer 108. For the example, the display layer 108 is positioned between the touch sensor layer 106 and the capacitor array layer 104. The display layer 108, however, may be placed in other positions relative to the other layers of the touch screen 100. Regardless of the position of the display layer 108 within the touch screen 100, the display layer 108 may display information (e.g., text, pictures, graphics, icons, video, etc.) for a user. For the example, the display layer 108 comprises a liquid crystal display (“LCD”), which is a thin, flat panel used for electronically displaying information. An LCD is an electronically-modulated optical device made up of any number of pixels filled with liquid crystals and arrayed in front of a light source (e.g., backlight) or reflector to produce images in color or monochrome. Although an LCD is described, any other suitable display technology may be used in the display layer 108.
The touch screen 100 also includes the overlay 110 in the exemplary embodiment. An example of suitable structure of the overlay 110 includes using a layer of material that is substantially transparent, flexible, and thin so that the other layers of the touch screen 100 may be visible to the user and so that the force imparted onto the touch screen 100 can be adequately imparted onto the PETA layers 102 and the touch sensor layer 106. As described above, the layers of the touch screen 100 may be rearranged, omitted, or substituted with other materials, devices, or structures that accomplish the same functionality. In some circumstances, additional layers not shown in
The capacitor array layer 404 is coupled to the PETA layer 400 by the diode rectifier circuit 402. However, in various embodiments, the diode rectifier circuit 402 may be omitted or replaced with other circuitry that has the same functionality as the diode rectifier circuit 402. The capacitor array layer 404 includes a plurality of capacitors that may be charged by the PETs of the PETA layer 400 in response to a force being applied to the PETA layer 400. As discussed above, a plurality of capacitor array layers may be used in some circumstances.
The capacitor array layer 404 is coupled to the controller 406. The controller 406 is configured to determine a charge level of the capacitor array layer 404 and to control the discharge of the capacitor array layer 404 based on the determined charge level. The controller 406 is any computer, processor, processor arrangement logic circuit, or combination thereof that performs the control functions discussed herein. In some circumstances, the controller 406 is the only controller within the electronic device 300, effectively handling all processing and control functions for electronic device 300, including controlling the discharge of the capacitor array layer 404. Accordingly, the controller may facilitate the overall functionality of the electronic device 300. In other situations, the controller 406 is only configured to control the discharge of the capacitor array layer 404 while another one or more controllers (not shown) are configured to handle all other processing functions of the electronic device 300 that are not related to the discharge of the capacitor array layer 404. In yet other embodiments, controller 406 is configured to control the discharge of the capacitor array layer 404 as well as some, but not all, of the other processing requirements of the electronic device 300.
The discharge of the capacitor array layer 404 may take many forms. In this regard, various examples of circuitry may be used alone or in combination to discharge the capacitor array layer 404 and to also charge other components with the discharged electric charge from the capacitor array layer 404. Several examples of such discharging circuitry and charging circuitry are described below. Other circuit and component configurations beyond those shown below may be used to discharge the capacitor array layer 404 and to charge other components with the discharged electric charge from the capacitor array layer 404.
For example, the controller 406 may determine that the capacitor array layer 404 should be discharged directly to power one or more logical circuits 408 of the electronic device. In order to accomplish this, the controller 406 sends a signal via the line 410 to discharge the capacitor array layer 404 to DC-DC (e.g., Direct Current to Direct Current) converter 412 coupled to the capacitor array layer 404. The DC-DC converter 412 ensures that the electric charge sent to the logical circuits 408 is of the proper voltage and/or current. The controller 406 also sends a signal via the line 413 to switch the output of the DC-DC converter 412 to the logical circuits 408. In addition, the controller 406 would cut, or at least reduce the level of, the power supply from the battery 414 of the electronic device to the logical circuits 408. An example of a suitable technique for disconnecting the battery 414 includes sending a control signal from the controller 406 during the time that the logical circuits 408 are being powered by the charge from the capacitor array layer 404. Once the charge from the capacitor array layer 404 can no longer adequately power the logical circuits 408, the power supply from the battery 414 may be restored. In some circumstances, the power supply from the battery 414 may be restored prior to the point in time at which the charge from the capacitor array layer 404 can no longer power the logical circuits 408.
In some situations, the DC-DC converter 412 is omitted. For example, if the voltage of the electric charge that is discharged from the capacitor array layer 404 is appropriate for whichever of the logical circuits 408 are to be powered by the electric charge, the DC-DC converter 412 may be omitted. In some circumstances, the DC-DC converter 412 may still be present but may just be bypassed if the voltage of the electric charge that is discharged from the capacitor array layer 404 is appropriate for whichever of the logical circuits 408 are to be powered by the electric charge.
Also, the logical circuits 408, although shown as a single entity, may alternatively represent separate logical circuits. For example, logical circuits that may be powered by the electric charge from the capacitor array layer 404 may include a real-time clock, a liquid crystal display, or a backlighting device.
In another embodiment, the controller 406 may determine that the battery 414 should be recharged with the electric charge stored in the capacitor array layer 404. In this case, the controller 406 sends a signal via the line 410 to discharge the capacitor array layer 404 to the DC-DC converter 412, ensuring that the electric charge has the proper voltage to charge the battery 414. The controller 406 also sends a signal via the line 418 to switch the output of the DC-DC converter 412 to the battery 414. Alternatively, the DC-DC converter may be omitted or bypassed if the voltage of the electric charge from the capacitor array layer 404 is appropriate for the battery 414.
In some circumstances, the controller 406 determines that the charge from the capacitor array layer 404 should be discharged to a secondary power supply 420. The secondary power supply 420 is any device or structure capable of storing a charge and releasing the stored charge in order to recharge the battery 414 or to power the logical circuits 408. For example, the secondary power supply 420 could be a super capacitor, which is an electrochemical capacitor that has an unusually high energy density when compared to common capacitors, typically on the order of thousands of times greater than a high capacity electrolytic capacitor. Where a super capacitor is used, the super capacitor may have a low voltage rating and a high capacitance. In other circumstances, the secondary power supply 420 is another battery.
Regardless of the exact device used as the secondary power supply 420, the controller 406 discharges the capacitor array layer 404 by sending a signal via the line 410 to discharge the capacitor array layer 404 to the DC-DC converter 412. In this example, the controller 406 also sends a signal via the line 422 to switch the output of the DC-DC converter 412 to the secondary power supply 420. Alternatively, the DC-DC converter 412 may be omitted or bypassed if the voltage of the electric charge from the capacitor array layer 404 is proper for the secondary power supply 420.
After the secondary power supply 420 is charged, the controller 406 may discharge the secondary power supply 420 in order to charge the battery 414 by sending a signal via the line 424 to discharge the secondary power supply 420. Alternatively, the controller 406 may discharge the secondary power supply 420 in order to power the logical circuits 408 by sending a signal via the line 426 to discharge the secondary power supply 420. The controller 406 may also cut, or at least reduce the level of, the power supply to the logical circuits 408 from the battery 414 as long as power is being supplied to the logical circuits 408 by the secondary power supply 420. Controller 406 can cut or reduce the power supply from the battery 414 by sending a signal via the line 416.
One embodiment of a method is shown is shown in
At block 504, the charge level of the capacitor array layer is determined. As described above, a controller is used to determine the charge level. Alternatively, any other suitable circuitry and/or components may be used that are capable of determining the charge level. In this regard, “determined” can mean many things. For example, “determined” can mean identified, calculated, derived, measured, etc.
At block 506, the capacitor array layer is discharged, based on the determined charge level. As described previously, the charged capacitor array layer may be discharged in order to power one or more logical circuits of an electronic device. In some situations, the method may further include selecting one or more of a plurality of logical circuits to be powered by discharging the capacitor array layer. This selection may be based on the determined charge level, on a priority level associated with each logical circuit, on whether the determined charge level is sufficient to power a logical circuit for at least a predetermined minimum period of time, or on a combination of these criteria.
In some circumstances, the capacitor array layer is discharged in order to charge a battery of an electronic device, to charge a secondary power source of the electronic device, or both. If the battery of the electronic device is charged with the electric charge from the capacitor array layer, the battery may be used to power the logical circuits. If the secondary power source is charged with the electric charge from the capacitor array layer, the secondary power source may be discharged in order to power the logical circuits. Alternatively, the charged secondary power source may also be discharged in order to charge the battery.
Referring now to
At block 602, the controller calculates the total charge present on the secondary power supply. At decision block 604, the controller determines if the total charge is sufficient to power the selected logical circuit for at least a predetermined minimum period of time. In various embodiments, the predetermined minimum period of time may be different for each logical circuit. In addition, the minimum period of time may be fixed or may be modified. For example, the minimum period of time may be factory preset for the particular electronic device, may be selected by the controller, may be selected directly by the user, or may be indirectly selected by the user (e.g., via selection of various power management profiles).
If the total charge is sufficient, the secondary power supply is discharged in order to power the selected logical circuit for at least the predetermined minimum period of time, at block 606. If the total charge is not sufficient, the controller may determine, at block 608, if there is any other logical circuit on the list of logical circuits with a lower priority that can be powered by the total charge for at least the predetermined minimum period of time. If there are not any other logical circuits on the list that meet the criteria of block 608, the secondary power source continues to collect charges from the PETA layer (e.g., via the capacitor array layer). If there is another logical circuit that meets the criteria of block 608, the controller selects the logical circuit that meets the criteria, at block 612, and discharges the secondary power supply to power the selected logical circuit for at least the predetermined minimum period of time, at block 606.
Although not shown in
In some circumstances, the secondary power supply could directly collect the charges from the PETA layer by either omitting the capacitor array layer or bypassing the capacitor array layer. Likewise, the battery of the electronic device could directly collect the charges from the PETA layer by either omitting the capacitor array layer or bypassing the capacitor array layer. Similarly, any of the logical circuits could be directly powered by the PETA layer be either omitting the capacitor array layer or bypassing the capacitor array layer.
As can be readily seen by the foregoing description, numerous advantages may be obtained by utilizing the disclosed embodiments. For example, the battery of an electronic device with a power-generating touch screen will not need to be recharged as often since power can be generated through use of the touch screen. In some embodiments, the touch screen can also generate power when the electronic device is turned off or in a low-power mode (e.g., standby mode).
In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software, the functions may be stored as one or more instructions or code on a computer-readable medium. For example, computer code that may be used by the controller to determine the charge level of the capacitor array layer and to control discharge of the capacitor array layer may be stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code in the form of instructions or data structures and that can be accessed by a computer. Disk and disc, as used herein, includes compact disc (CD), laser disc, optical disc, digital versatile disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.
The various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosed embodiments.
The methods disclosed herein comprise one or more steps or actions for achieving the described method. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims. Additionally, various steps may be omitted, substituted, or added to the particular methods described above without departing from the scope of the disclosed embodiments.
Clearly, other embodiments and modifications will occur readily to those of ordinary skill in the art in view of these teachings. The above description is illustrative and not restrictive. These embodiments are to be limited only by the following claims, which include all such embodiments and modifications when viewed in conjunction with the above specification and accompanying drawings. The scope of the embodiments should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents.
