Patent Application
20090002199
The present invention relates generally to electronic devices and, more specifically, to using piezoelectric sensing with force detection as user input means in user interface modules.
User input means (such as a user interface) of an electronic device can be implemented in various ways. Touch pads, keyboards, keymats, touch-screen, etc. are well known user interfaces especially for portable devices as laptop computers and mobile telephones. A touch pad is an input device which typically includes a sensor and an associate circuitry. When a user moves a stylus or a finger to touch (or to put in a close proximity) the touch pad, that contact effects the sensor and is detected by the circuitry. There are various mechanisms for detecting the point of contact on the touch pad.
One approach for detecting a user input is generating an electrical field and detecting a deformation of the electric field by a user. The electric field can be generated, for instance, within the area of a touch-screen. The disturbance of that field caused by the object may then depend on the position at which the touch-screen is touched by the object (e.g., stylus, finger of the user, etc.). For generating and monitoring such electrical field, different sensor technologies can be employed. One option is to use a capacitive detection. Capacitive touch sensing technology is used currently in multiple mobile devices for example in various MP3 players and mobile phones.
Among multiple capacitive touch pad principles, a capacitive detector can comprise at least one conductive plate or electrode, which forms a capacitance with at least one another conductive plate or electrode. In a capacitive detector, an electric filed is set between these electrodes. Then the disturbances of the electric field induced, for example, by a user finger (e.g., by touching, which can act as grounding or disturbing element) can be detected by monitoring the capacitance value between these two electrodes (e.g., using the measurement circuitry). Thus capacitance values (i.e., changes in the disturbed electric field) can be used for detecting whether there is some object in close proximity of the detector or not, and at which position. This principle can be used in a matrix type grid sensor arrangement with rx and tx electrodes separated by a gap, wherein the object (e.g., a finger) causes disturbances in coupling the signal which is detected by the measurement circuitry, as disclosed, for example, in U.S. Pat. No. 6,452,514 “Capacitive Sensor and Array” by H. Philipp.
There are other multiple alternative methods and variations in the measurement technique in using the capacitance measurement for detection. For example, principles, disclosed in US patent U.S. Pat. No. 6,466,036 “Charge Transfer Capacitance Measurement Circuit” by H. Philipp, can be applied to a semi-conductive plate (or possibly to a conductive plate) to measure the location of the finger as well, using the following. Charge pulses can be injected from a number of electrodes placed around the touch plane (e.g., semi-conducting touch plane) at least three preferably at least four electrodes. There can be more electrodes for increased accuracy and performance. These charge pulses generate electric field around the semi-conductive plane and the finger absorbs energy of some of the pulses (capacitive connection to the plane). The injected charges are collected and counted. The sensing electrodes from the corners of the touch plane have resistance values to the point which forms the capacitance connection to the finger, i.e., changes in the resistance can be detected as changes in an electric current (resistive-capacitive detection). Relative resistance values determine the distances from the corners indicating coordinate values.
However, capacitive sensing measurement cannot distinguish sometimes between false and correct capacitive signals, which may cause false activations or interference. Examples of these situations could be hand shadow capacitance, e.g., if other fingers (the same or another hand) are is a close proximity of the sensor, or metallic objects at the sensor proximity area. These factors can cause inaccurate sensor behavior. Therefore, the capacitive touch pad can operate very well as a touch pad after an appropriate selection but the actual selection is usually done with separate keys using other methods. In principle, the activation in mobile devices could be done with the same touch pad, however, it is difficult to do with a capacitive sensing based touch pad, because the activation threshold varies according to conditions.
Furthermore, the capacitive sensing technology can detect force as the capacitive signal level increases due to more firm press (e.g., finger squeezes). However, this detection may be not accurate because the finger size varies, and there could be interfering capacitive signals in the proximity area as mentioned herein. Alternative approaches are also unreliable and limited in accuracy and linearity of the response as a function of applied force. For example, a resistive touch pad or touch screen can detect a discrete force when the two layers bend and contact each other galvanically. Also using domes with switches (activated by pressing) beneath the pad can be used for a force detection.
Piezoelectric transducers are used primarily in touch-type controls (user interfaces) for providing a feedback signal (tactile signal, vibration signal, etc.). For example, in U.S. Pat. No. 6,757,002 “Track Pad Pointing Device with Areas of Specialized Function” by G. Oross et al., a vibration source includes a piezoelectric material activated in a switch configuration when a finger in a special touch sensing area closes the switch causing a vibration to occur adjacent to the finger within the activated special touch sensing area. In another example, U.S. Pat. No. 7,148,875 “Haptic Feddback fro Touchpad and Other Touch Controls” by L. Rosenberg et al., a piezoelectric actuator provides a force on the touchpad when an electrical signal is applied to the actuator (typically, a piezoelectric actuator includes two layers which can move relative to each other when a current is applied to the actuator: the grounded portion of the actuator remains stationary with respect to the surrounding housing while the moving portion of the actuator and the touchpad move with respect to the housing).
According to a first aspect of the invention, an apparatus, comprises: a user interface layer comprising a touch surface; and a piezoelectric layer, configured to provide one or more levels of a force detection signal in response to an object touching the touch surface with one or more levels of a pressing force for applying a mechanical stress to the piezoelectric layer, wherein the one or more levels of the force detection signal correspond to the one or more levels of the pressing force and are for communicating one or more predetermined commands.
According further to the first aspect of the invention, the level of the force detection signal may be proportional to the level of a predetermined force. Further, the apparatus may be configured to use the one or more predetermined commands for continuously scrolling information using varying the force detection signal as a function of the pressing force.
Further according to the first aspect of the invention, the apparatus may further comprise: a first electrode layer; and a second electrode layer, wherein the piezoelectric layer is between the first electrode layer and the second electrode layer for providing the force detection signal. Further, the first electrode layer may be a touch sensor/electrode layer, configured to provide a sensor signal as a function of a location of an object on or near the non-flat touch surface when the object touches or in a close proximity of the touch surface, and wherein the second electrode layer may be a reference potential layer or a ground electrode layer.
Still further according to the first aspect of the invention, the apparatus may further comprise: a touch sensor layer, configured to provide a sensor signal as a function of a location of an object on or near the touch surface when the object touches or is in a close proximity to the touch surface, wherein the force detection signal and the sensor signal are used in combination to provide control information. Further, the user interface layer, the touch sensor layer and the piezoelectric layer may be parts of a user interface module. Still further, the touch sensor layer may comprise a touch sensor for providing the sensor signal and the touch sensor may be a capacitive sensor, a resistive-capacitive sensor or a resistive sensor. Yet still further, the touch sensor layer may be an impedance sensor conductive layer of a rectangular shape with four contact points at corners of the touch sensor.
According further to the first aspect of the invention, the piezoelectric layer may be made of a polymer or a polymer and ceramic mixture.
Yet still further according to the first aspect of the invention, the apparatus may further comprise: a semi-soft polymer layer configured to provide a pre-selected bending level of the piezoelectric layer.
According still further to the first aspect of the invention, the apparatus may be an electronic device configured for wireless communications.
According to a second aspect of the invention, a user interface module, comprises: a user interface layer comprising a touch surface; and a piezoelectric layer, configured to provide one or more levels of a force detection signal in response to an object touching the touch surface with one or more levels of a pressing force for applying a mechanical stress to the piezoelectric layer, wherein the one or more levels of the force detection signal correspond to the one or more levels of the pressing force and are for communicating one or more predetermined commands to an electronic device.
According further to the second aspect of the invention, the user interface module may be a part of the electronic device.
Further according to the second aspect of the invention, the user interface module may be connected to the electronic device by an electrical or wireless connection.
Still further according to the second aspect of the invention, the level of the force detection signal may be proportional to the level of a predetermined force.
According further to the second aspect of the invention, the user interface module may be configured to use the one or more predetermined commands for continuously scrolling information using varying the force detection signal as a function of the pressing force.
According still further to the second aspect of the invention, the user interface module may further comprise: a first electrode layer; and a second electrode layer, wherein the piezoelectric layer is between the first electrode layer and the second electrode layer for providing the force detection signal.
According further still to the second aspect of the invention, the first electrode layer may be a touch sensor/electrode layer, configured to provide a sensor signal as a function of a location of an object on or near the non-flat touch surface when the object touches or in a close proximity of the touch surface, and wherein the second electrode layer may be a reference potential layer or a ground electrode layer.
According yet further still to the second aspect of the invention, the user interface module may further comprises: a touch sensor layer, configured to provide a sensor signal as a function of a location of an object on or near the touch surface when the object touches or is in a close proximity to the touch surface, wherein the force detection signal and the sensor signal are used in combination to provide control information. Further, the user interface layer, the touch sensor layer and the piezoelectric layer may be parts of a user interface module. Still further, the touch sensor layer may comprise a touch sensor for providing the sensor signal and the touch sensor may be a capacitive sensor, a resistive-capacitive sensor or a resistive sensor. Yet still further, the touch sensor layer may be an impedance sensor conductive layer of a rectangular shape with four contact points at corners of the touch sensor.
Yet still further according to the second aspect of the invention, the piezoelectric layer may be made of a polymer or a polymer and ceramic mixture.
Still yet further according to the second aspect of the invention, the user interface module may further comprise: a semi-soft polymer layer configured to provide a pre-selected bending level of the piezoelectric layer.
According to a third aspect of the invention, a method, comprises: pressing a touch surface of a user interface layer by an object with a pressing force for applying a mechanical stress to a piezoelectric layer; and providing a force detection signal in response to the object touching the touch surface with the pressing force by the piezoelectric layer, wherein the piezoelectric layer is configured to provide one or more levels of the force detection signal in response to the object touching the touch surface with one or more levels of the pressing force, wherein the one or more levels of the force detection signal correspond to the one or more levels of the pressing force and are for communicating at least two predetermined commands to an electronic device.
According further to the third aspect of the invention, the pressing may be for providing the force detection signal to wake up the electronic device.
Further according to the third aspect of the invention, the method may further comprise: further touching a touch surface of the user interface layer by the object; and providing by a touch sensor layer a sensor signal as a function of a location of the object on the touch surface in response to the further touching, wherein the force detection signal and the sensor signal are used in combination to provide control information to an electronic device. Further, the user interface layer, the touch sensor layer and the piezoelectric layer may be parts of a user interface module. Still further, the touch sensor layer may comprise a touch sensor for providing the sensor signal and the touch sensor may be a capacitive sensor, a resistive-capacitive sensor or a resistive sensor. Yet still further, the touch sensor layer may be an impedance sensor conductive layer of a rectangular shape with four contact points at corners of the touch sensor.
Still further according to the third aspect of the invention, the level of the force detection signal may be proportional to the level of a predetermined force.
According further to the third aspect of the invention, the one or more predetermined commands may be for continuously scrolling information using varying the force detection signal as a function of the pressing force.
According still further to the third aspect of the invention, the piezoelectric layer may be made of a polymer or a polymer and ceramic mixture.
For a better understanding of the nature and objects of the present invention, reference is made to the following detailed description taken in conjunction with the following drawings, in which:
A new apparatus and method are presented for providing and using piezoelectric sensing with force detection as user input means possibly in combination with touch sensing methods in a user interface module (e.g., touch pad, keyboard, keymat, touch-screen, etc.).
According to an embodiment of the present invention, a piezoelectric layer can be configured to provide a force detection signal in response to an object (e.g., finger, stylus, etc.) touching or pressing a touch surface (or a user interface layer) of the user interface module with a pressing force for applying a mechanical stress to the piezoelectric layer causing strain bending in the piezoelectric layer material and thus generating an electric voltage (i.e., the force detection signal), wherein the force detection signal is a function, e.g., a linear function, of the piezoelectric layer force. The force detection signal can have a predetermined number of levels (one or more) as a function of corresponding levels of applied force, e.g., for providing predetermined commands (e.g., selections, control information, etc.) to an electronic device used with the user interface module. Moreover, this force detection signal can vary continuously as a function of said force, e.g., for providing scrolling of information in said electronic device (e.g., on a display).
It is noted that the electric device can comprise the user interface module or the user interface module can be used remotely using an electrical or a wireless connection. It is further noted that the piezoelectric layer can be made of a polymer, a polymer and ceramic mixture or similar materials. An additional semi-soft polymer layer can be used to provide a pre-selected bending level of said piezoelectric layer.
According to a further embodiment of the present invention, the force detection can be used in combination with a touch sensor layer comprising touch sensor/sensors (e.g., a capacitive sensor, a resistive-capacitive sensor, a resistive sensor, etc.) and configured to provide a sensor signal as a function of a location of an object on or near said touch surface when said object touches or is in a close proximity to said touch surface. Then said force detection signal and said sensor signal can be used in combination to provide control information to the electronic device. Combination of these two technologies (the force detection using piezoelectric sensing and touch sensing) can be used to enhance input devices for mobile, wireless and other devices and applications.
A few scenarios for using new or enhanced input devices, according to embodiments of the present invention, are as follows.
For example, the force detection with piezoelectric sensing can be used to activate a selection in the electronic device when the finger is pressed firmly with the pressing force like in a normal key press on a touch surface (layer) of the user interface module. After the selection is made, the same area (the touch surface of the user interface module) can be used as a touch pad by pressing more gently, wherein coordinates (location of the finger) is determined by the touch sensing (e.g., capacitive measurement).
In another scenario, the force detection using piezoelectric sensing can be used to generate an activation pulse to wake up the device, which is a notable advantage because the measurement circuitry do not have to be in an active measurement state all the time.
Moreover, according to another embodiment, the initial activation (selection) can be performed using touch sensing (e.g., capacitive, resistive, etc.) or another conventional sensing using for example dome technology, and then the force detection with piezoelectric sensing can be used for providing the force detection signal proportional to the applied force as a scrolling mechanism of the information in the electronic device through said user interface module. It is also noted that the initial activation (selection) can be performed using the piezoelectric sensing as well by using a signal of a predetermined pressing pattern (e.g., by pressing the touch surface two or more times in sequence).
The piezoelectric layer 12 can be made of a polymer, a polymer and ceramic mixture, or similar materials. The piezoelectric layer 12 is placed between a first electrode (conductive) layer 14 and a second electrode conductive layer 16 (e.g., a reference potential layer or a ground electrode layer) for providing the force detection signal (i.e., a voltage generated between the electrodes layers 14 and 16) when a pressing force is applied in a direction A to a user interface layer 20 at any location as shown in
According to a further embodiment, the first electrode layer 14 shown in
There are multiple alternatives for the capacitive touch sensor layer depending on the measurement principle and measurement arrangement as briefly described in the Background section. For example, the capacitive touch sensor layer can be homogenous and semi-conductive with a resistivity, e.g., 500 Ohms/square to 50 kOhms/square or conducting using a principle outlined in the US patent U.S. Pat. No. 6,466,036“Charge Transfer Capacitance Measurement Circuit” by H. Philipp as illustrated in
In impedance measurement sensing technology as illustrated in
Also other types of capacitive and resistive sensors can be utilized in the layer 14. The capacitive touch sensor layer can be a matrix type of grid, using a measurement principle outlined in the U.S. Pat. No. 6,452,514 “Capacitive Sensor and Array” by H. Philipp (in this method the sensor electrodes are preferably conductive but can be semi-conductive as well). It is further noted that combinations and variations in the measurement principles and arrangements are possible. Since the electric fields are different in different sensor arrangement and measurement principle, thus, the dielectric variations should be applicable and implemented depending on the measurement principle and arrangement. Moreover, in order to separate the touch sensor signal and the force detection signals, different signal modulation schemes can be used which are known to a person skilled in the art.
It is noted that the user interface module 10 shown in
The flow chart of
The flow chart of
It is noted that various embodiments of the present invention recited herein can be used separately, combined or selectively combined for specific applications.
It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention, and the appended claims are intended to cover such modifications and arrangements.
This application claims priority from U.S. Patent Application Ser. No. 60/937,520, filed on Jun. 28, 2007.
| Number | Date | Country | |
|---|---|---|---|
| 60937520 | Jun 2007 | US |
