Multi-touch sensing device with multi-frequency capacitive sensing

A touch screen and projected capacitive technology, applied in the direction of electrical digital data processing, input/output process of data processing, instruments, etc., can solve problems such as difficult to use, mistaken, and interference in the electromagnetic environment

Inactive Publication Date: 2012-12-26
THALES SA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0016] In summary, current projected capacitive touchscreens suffer from a number of deficiencies that make them difficult to use in an aircraft cockpit or any environment of importance
In practice, as already seen, the detection of touches can be falsified by phantom touches or external electromagnetic interference
Moreover, the measurement principle interferes with the electromagnetic environment

Method used

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  • Multi-touch sensing device with multi-frequency capacitive sensing
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  • Multi-touch sensing device with multi-frequency capacitive sensing

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Embodiment Construction

[0038] A simplified model exists for electrically describing a capacitive touch sensing device comprising a matrix of electrodes consisting of conductive rows and columns. It consists of a touch representation in which the operator capacitively couples his or her finger with the matrix by projecting the surface of his or her finger onto the tablet. The surface is covered with at least two electrodes, the first on the rows and the second on the columns. then the operator will be considered to have added capacitance C between ground and at least the row or column concerned d . However, the model is still local and does not take into account the measurement environment.

[0039] figure 2 A more complex model of a capacitive matrix device is shown. In fact, each row is connected to measurement and / or power supply devices via analog switches. These switches increase the coupling capacitance C with respect to ground m and has a resistor R that attenuates the signal being meas...

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PUM

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Abstract

The general field of the invention is that of touchscreen devices with projected capacitive detection comprising a matrix-form touch pad comprising conductive rows and columns, said pad being linked to control means and electronic reception and analysis means. The control means generate, for each conductive row and column, a first periodic emission voltage emitted at a first working frequency and a second periodic emission voltage emitted at a second discrimination frequency, different from the first frequency. The electronic reception and analysis means are arranged so as to determine, for each row and for each column, the impedance of a first reception voltage at the working frequency and the impedance of a second reception voltage at the discrimination frequency. According to predetermined values, the values of the two impedances are representative of a touch on the touch pad and its location on the row or on the column concerned.

Description

technical field [0001] The field of the invention relates to touch-sensitive surfaces or "touch screens" with capacitive detection, and in particular to so-called "multi-touch" touch-sensitive surfaces that allow the detection of two simultaneous touches. This function is necessary in forming eg image "zooming" or rotation. The invention can be applied for different purposes, but it is more suitable for restraints and aircraft dashboards in the field of aviation. Background technique [0002] So-called "projected" capacitive detection consists in generating a detection matrix arranged to detect local changes in capacitance caused by the approach of a user's finger or any other conductive designated object. So-called projected capacitive technology has the following two main variables: [0003] - "self-capacitance" detection, which consists in reading the rows and then the columns of the key array of the matrix; [0004] - So-called "mutual capacitance" detection, which co...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F3/044
CPCG06F2203/04104G06F3/0416G06F3/044G06F3/04166G06F3/0446
Inventor P·科尼Y·桑塔格
Owner THALES SA
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