Patent Application
20060066585
The present invention relates to an apparatus for induced capacitor, and more particularly, to an apparatus for induced capacitor capable of conveniently adjusting the equivalent capacitance of capacitance sensing devices arranged therein.
Generally, there are two types of sensing interfaces used by touch panels, which are capacitive type and resistive type. In the case of the capacitive type, a plurality of capacitive touch keys, serving as a sensing medium, have to be formed uniformly on an insulating substrate, such as FR4 substrate and membrane, etc.
The patterning designs of capacitive touch key commonly available are spiral pattern as shown in
However, the touch keys are possibly not being charged uniformly due to several factors associated therewith, for example, amount of the touch keys arranged in a touch panel, deficient design of the touch keys and an unevenly formed insulating substrate. In these cases, the potentials generated on the touch keys are not identical (not uniform). Even, a number of potentials may be lower than the threshold and thus the corresponding touch keys are erroneously activated with the associated function by the control circuit at a time before the corresponding touch keys are touched/pressed by the user. Therefore, a touch panel has to be designed with capability of adjusting the equivalent capacitance of each touch key as desired so that uniform potentials may be obtained as a pulse charging the touch keys is applied.
However, to adjust the equivalent capacitances in the spiral, comb-like or snail-like touch keys, the thickness of wires provided within the patterns is to be adjusted on the basis following the function of C=(ε×A)/D, wherein C is equivalent capacitance, ε is dielectric coefficient, A is area and D is distance between wires. For example, while it is intended to increase the equivalent capacitance, either the overall pattern is to be enlarged so that the wires in the pattern are widened (i.e. areas of the wires increased) or the overall pattern is to be shrunk for reducing the separations between wires. However, if the equivalent capacitance is increased by enlarging the area, the complexity of designing the touch keys as well as the cost of producing the same may increase since the touch keys may have different shapes and dimensions, and if the equivalent capacitance is increased by reducing the separation between wires, the electric fields induced by the equivalent capacitances in the touch keys reduces correspondingly, which causes the touch keys to have poor sensitivity and functionality.
It is, therefore, an object of the present invention is to provide a capacitive sensing device capable of conveniently adjusting the equivalent capacitance of the same while the area of the device is maintained unchanged.
It is another object to provide an apparatus for induced capacitor capable of conveniently adjusting the equivalent capacitance of each capacitance sensing devices arranged therein while the overall area of the plural capacitance sensing devices arranged therein is being maintained unchanged.
The capacitance sensing device of the present invention comprises: a first electrode; and a second electrode, being disposed circumferentially surrounding the first electrode while separating the second electrode from first electrode by a distance so as to form an equivalent capacitance therebetween.
The apparatus for induced capacitor of the present invention comprises: an insulating substrate; and a plurality of capacitive sensing devices, arranged on the insulating substrate in a matrix form; wherein each capacitive sensing device further comprises: a first electrode; and a second electrode, being disposed circumferentially surrounding the first electrode while separating the second electrode from first electrode by a distance so as to form an equivalent capacitance therebetween.
Pleas refer to
The insulating substrate 41 is a circuit board selected from the group consisting of a FR4 circuit board, a circuit membrane and the likes. Each of the capacitive sensing devices 42 is used as a touch key, being independently arranged on the insulating substrate 41 and together forming a matrix form. Referring to
In this embodiment, the first electrode 43 is a structure of circular profile having an area (A). The second electrode 44 is a ring, being disposed circumferentially surrounding the first electrode while separating the second electrode from first electrode by a distance (D) so as to form an equivalent capacitance therebetween. As such, an equivalent capacitance is formed between the first electrode 43 and second electrodes 44 and the equivalent capacitance may be obtained based on the function of C=(ε×A)/D, wherein ε is dielectric coefficient of the insulating substrate.
As seen in
However, the pulse may attenuate as the transmit distance increases and the capacitive sensing devices may have deficient designs or the material of the insulating substrate may non-uniformly distributed, such that the potentials of the capacitive sensing devices 42 may not be uniform, i.e. not identical as compared to one another. In this case, the equivalent capacitances of the capacitive sensing devices 42 should be adequately adjusted with the consideration of the factors mentioned taken. As said in the foregoing context in the prior art section, the areas of the capacitive sensing devices 42 are preferably kept constant so as not to increase cost and complexity of the device. In this regard, an outer rim of the second electrode 44 is kept fixed and only the distance D between an inner rim of the second electrode 44 and the first electrode 43 is varied for each capacitive sensing device 42 to adjust the equivalent capacitance of the capacitive sensing device 42. As such, the equivalent capacitance may be adjusted to a desired value without compromising a need of the area of the corresponding capacitive sensing device.
One of the adjustment methods with respect to the distance between the first electrode 43 and the inner rim of the second electrode 44 may be performed with reference to
Therefore, the equivalent capacitance of each of the capacitive sensing devices in the apparatus for induced capacitor may be adjusted freely by varying the structures of the pairs of the first and second electrodes 43,44 without changing the overall area of each of the capacitive sensing devices 42 and thus the whole capacitive sensing devices 42. After the adjustment, the capacitive sensing devices 42 may have uniform/identical potentials as compared to one another when charged so as to avoid erroneous actions occurred and improve the sensitivity of the touch panel.
Although a pattern of the first electrode 43 in the capacitive sensing device 42 has been described with the specific pattern as above used, the pattern of the first electrode 43 may also be a structure of rectangle or other polygons or equilateral polygons profile. The inventive capacitive sensing devices may also be utilized in capacitive sensing associated electronic switches in addition to general capacitive touch panels, such as the one as used for the above description, so as to solve a problem of uniform equivalent capacitances taken place in the electronic switches.
While the preferred embodiment of the invention has been set forth for the purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 93128953 | Sep 2004 | TW | national |
