Patent Application
20090184930
Position detecting systems including display panels are known in the art, for example, as an alternative to keyboard and/or mouse input devices for computer systems, which devices are limited where handwriting and/or hand-drawing input is desired. Although a number of position detecting systems, which receive positional information, for example, from a stylus or pen, have been described, there is still a need for position detecting systems incorporating new types of sensors that, when arranged in an array corresponding to an array of pixel elements of a liquid crystal display (LCD), provide relatively high spatial resolution and relatively fast response for a position detecting display panel, without increasing an operating cost and/or complexity of the panel. Thus, the present disclosure pertains to position detecting systems and more particularly position detecting display panels incorporating an array of sensors coupled to an array of pixel elements.
An array of sensors, which is coupled to an array of pixel elements in a position detecting display panel of the present disclosure, includes sensors that are each registered with a corresponding pixel element of the array of pixel elements, and that each include a material exhibiting magneto-electric behavior in response to a magnetic field source. Systems of the present disclosure include the position detecting display panel and at least one separate stylus, which includes the magnetic field source. A voltage source, that is operably coupled to each sensor and each pixel element, applies a voltage across one or more particular pixel elements, according to the magneto-electric behavior of the corresponding sensor(s), when the magnetic field source is brought into proximity the corresponding sensor(s).
The following drawings are illustrative of particular embodiments of the disclosure and therefore do not limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description. Embodiments of the disclosure will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.
The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides practical illustrations for implementing exemplary embodiments.
In typical LCD's, each pixel element 13 comprises a liquid crystal material contained between two opposing plates, each formed by a transparent electrode and polarizing filter; each of the electrodes, which are in contact with the liquid crystal material, bears a polymer coating that interfaces with the liquid crystal material to affect an alignment of the molecules thereof in the vicinity of the plates. In a twisted nematic device, the liquid crystal molecules in the vicinity of a first electrode are aligned orthogonally to those molecules in the vicinity of a second, opposing electrode, so that the molecules in between are arranged in a helical structure that spans the bulk of the liquid crystal material between the two electrodes and allows light to pass through the pixel element. By controlling a voltage applied across the two electrodes, light passing through each pixel element 13 may be polarized in varying degrees according to the voltage-affected alignment of the liquid crystal molecules.
In
Stylus 10 may include a permanent magnet to generate the magnetic field, or may include a conductor coil, for example, wound about a ferrite core, to actively generate the field by means of an applied current traveling through the coil. Magnetic fields of varying magnitudes may be generated by the latter type of stylus that includes the conductor coil, for example, to induce a range of signals generated by the sensor elements 15; each signal in the range may correspond to a different color in a range of colors to be displayed by pixels 13. Alternately, a range of signals may be induced by a group of passive-type styluses, each of which include a different permanent magnet generating a different magnitude of magnetic field.
According to some preferred embodiments, each sensor 15 of the array of sensors 15 includes a material that exhibits magneto-electric (ME) behavior in response to a magnetic field, for example, as generated by stylus 10. ME behavior is characterized by a coupling between electric and magnetic fields wherein an electric polarization orientation of the material exhibiting ME behavior is changed by an applied magnetic field, or visa versa. Examples of ME materials may be divided into two categories: 1.) composite materials including a piezoelectric constituent and a magnetostrictive constituent, examples of which include, without limitation, BaTiO3/CoFe2O4, PZT/CoZnFe2O4 and PZT/NiZnFe2O4 (wherein PZT may be PbZr1-xTixO3); and 2.) single-phase multiferroic compounds, examples of which include, without limitation, BiFeO3, BiMnO3, Cr2O3, Ti2O3, GaFeO3, PbFeNbO3, LiCOPO4 and TbPO4. ME materials have been researched, described, and suggested for sensor applications, for example, by Manfred Fiebig, in “Revival of the Magnetoelectric effect” (J. Phys. D: Appl. Phys. 38, R123 (2005)), and by Van E. Wood and A. E. Austin in “Possible applications for Magnetoelectric materials” (Int. J. Magnetism 5, 303 (1974)).
Inventors of the present disclosure propose, for incorporation into a position detecting display panel, for example, display panel 100, two types of sensors 15 that include an ME material.
For position detecting systems including sensor embodiments from each group described in conjunction with
The incorporated ME materials may also retain the electrical polarization orientation of sensors 15, as modified by the magnetic field generated by stylus 10, when power to the array of sensors 15 is turned off. Thus, sensors 15 directly store position detection information and, thereby obviate a need to ‘backup’ the information in a separate data storage system, for example, that employs memory chips. This non-volatility of the positioning detecting system that incorporates sensors 15 can facilitate relatively high speed and efficiency in combination with relatively low power consumption.
In the foregoing detailed description, the invention has been described with reference to specific embodiments. These implementations, as well as others, are within the scope of the appended claims.
