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CN-122018725-A - Capacitive touch pad detection method

CN122018725ACN 122018725 ACN122018725 ACN 122018725ACN-122018725-A

Abstract

The invention discloses a detection method of a capacitive touch pad, which relates to the technical field of flexible capacitive touch detection and signal processing, and the method comprises the steps of deducing deformation parameters through mutual capacitance difference and carrying out gridding correction on static coordinate mapping according to the deduced deformation parameters to form dynamic coordinate mapping which changes along with deformation, so that touch coordinate calculation is based on the current form rather than the initial flat state, and positioning deviation and track distortion under bending, stretching and wrinkling conditions are reduced; in addition, a touch mask is generated through self-capacitance touch signals, replacement and component decomposition are carried out on mutual capacitance difference of a mask coverage area, deformation deduction is enabled to mainly depend on global/local deformation characteristics so as to avoid local mutation of touch, and stability and usability of deformation parameters in the presence of touch are improved.

Inventors

  • PENG WU

Assignees

  • 深圳市鑫瀚成科技有限公司

Dates

Publication Date
20260512
Application Date
20260203

Claims (10)

  1. 1. A detection method of a capacitive touch pad is applied to a flexible touch pad comprising an electrode array, wherein the electrode array is used for forming a mutual capacitance measurement channel and a self capacitance measurement channel, and the method is characterized by comprising the following steps: step S1, obtaining a mutual capacitance measured value of the electrode array and forming a current mutual capacitance matrix; step S2, updating a reference mutual capacitance matrix based on the current mutual capacitance matrix when judging that effective touch is not present currently; Step S3, inputting a deformation deduction model based on the difference between the current mutual capacitance matrix and the reference mutual capacitance matrix to obtain deformation parameters representing the deformation of the flexible touch pad; s4, correcting a preset static coordinate mapping function according to the deformation parameters to obtain a dynamic coordinate mapping function; step S5, acquiring self-capacitance touch signals of the electrode array and performing baseline compensation based on the deformation parameters; and S6, mapping the electrode positions corresponding to the compensated self-capacitance touch signals to a virtual plane coordinate system through the dynamic coordinate mapping function, and calculating and outputting touch coordinates in the virtual plane coordinate system.
  2. 2. The method for detecting a capacitive touch pad according to claim 1, wherein the deformation deduction model is a parameterized model mapping differential characteristics of mutual capacitance to deformation parameters, and the deformation parameters at least include one of bending curvature and stretching ratio.
  3. 3. The method of claim 2, wherein the deformation parameters include global deformation components and local deformation components, and the local deformation components are used for characterizing spatial positions and amplitudes of wrinkles.
  4. 4. The method for detecting a capacitive touch pad according to claim 1, wherein the correcting the static coordinate mapping function includes performing nonlinear transformation on a coordinate grid according to the deformation parameter, and obtaining a mapping result of any electrode position through interpolation; The correction static coordinate mapping function comprises the steps of selecting grid nodes in a grid coordinate domain, performing triangulation, generating displacement correction of the grid nodes according to deformation parameters, limiting single displacement amplitude, superposing the displacement correction to static mapping coordinates of the nodes to form dynamic mapping coordinates of the nodes, positioning triangle units of any electrode positions, and obtaining dynamic mapping results of the electrode positions according to gravity center interpolation.
  5. 5. The method for detecting the capacitive touch pad according to claim 1, wherein the judging that no effective touch exists comprises the steps that a peak value of the self-capacitance touch signal is lower than a preset threshold, the number of space communication areas obtained after the self-capacitance touch signal is thresholded according to the preset threshold is zero, and a local abrupt change mode consistent with touch exists in the mutual capacitance difference; the preset threshold is a threshold determined based on self-capacitance touch signal noise statistics in a non-valid touch state.
  6. 6. The method of claim 1, wherein updating the reference mutual capacitance matrix uses recursive filtering or exponential smoothing and limits the single update amplitude to suppress short term disturbances.
  7. 7. The method of claim 1, wherein the baseline compensation comprises estimating an electrode-by-electrode self-capacitance baseline shift according to the deformation parameter and subtracting the self-capacitance baseline shift from a corresponding self-capacitance touch signal; The baseline compensation comprises updating electrode-by-electrode self-capacitance baseline drift amount under the gating condition without effective touch control, wherein the baseline drift amount comprises deformation related drift obtained through deformation parameter estimation and slow variation drift obtained through slow variation state recursion, the deformation related drift is obtained through partition sharing mapping coefficient estimation through deformation parameter estimation and limits single correction amplitude of the deformation related drift, the slow variation drift is updated in a recursion mode based on deviation between self-capacitance reading and drift prediction when the gating is allowed, updating gain is determined through error variance recursion, the deformation related drift and the slow variation drift are superimposed to form electrode-by-electrode total drift amount, and subtracted from corresponding self-capacitance touch control signals to obtain compensated self-capacitance touch control signals, and the partition sharing mapping coefficient is obtained through calibration under the condition without touch control samples and limits coefficient amplitude.
  8. 8. The method of claim 1, wherein the virtual planar coordinate system is defined by an electrode geometry of the flexible touch pad in a predetermined reference configuration.
  9. 9. The method of claim 1, wherein resolving touch coordinates includes normalizing and clustering the compensated self-capacitance touch signals, and calculating a center of gravity for each clustered region to output single-point or multi-point touch coordinates.
  10. 10. The method for detecting a capacitive touch pad according to claim 1, wherein the flexible touch pad is integrated in a wearable device or an electronic textile, and a carrier material of the flexible touch pad is bendable, stretchable or foldable.

Description

Capacitive touch pad detection method Technical Field The invention relates to the technical field of flexible capacitive touch detection and signal processing, in particular to a capacitive touch pad detection method. Background With the development of flexible electronic and wearable devices, the capacitive touch structure is used for bendable or stretchable interaction interfaces, such as a side touch area of the wearable device, a touch area of a foldable/curved display, and a touch/interaction structure integrated in a fabric, and the like, wherein the interfaces may be bent, stretched or wrinkled during use, so that the geometric form of the touch carrier is in a dynamic change state. When the touch surface is deformed, the relative position and coupling relation between electrodes are changed, so that a mapping model established based on the initial geometric relation is inconsistent with the actual physical surface, and thus, the calculation error or track distortion of the touch position can be caused; On the other hand, the deformation can also cause systematic variation or regional drift of capacitance measurement values, so that the systematic variation or regional drift is overlapped with local variation caused by touch, further the touch judgment reliability under a fixed threshold value or conventional baseline tracking is affected, false triggering or missed detection is caused, and although the technology for compensating the baseline drift exists in the conventional touch controller, the conventional touch controller is usually oriented to an environment slow variation or noise scene, and deformation disturbance which is fast, local and coupled with a touch signal is difficult to cover. Aiming at a deformable interface, the existing scheme comprises the steps of adding sensors such as strain/inertia and the like outside a touch electrode array to acquire deformation states and compensate, or establishing a correlation model between deformation and signals by utilizing capacitance matrix change of the touch electrode array, and jointly identifying touch and deformation characteristics by adopting a data driving method. Disclosure of Invention The present invention has been made in view of the above-described problems occurring in the prior art. The invention provides a capacitive touch pad detection method which solves the problems of coordinate distortion and baseline drift caused by flexible touch deformation and easiness in false touch and omission detection. In order to solve the technical problems, the invention provides the following technical scheme: The embodiment of the invention provides a detection method of a capacitive touch pad, which is applied to a flexible touch pad comprising an electrode array, wherein the electrode array is used for forming a mutual capacitance measurement channel and a self capacitance measurement channel, and the method comprises the following steps: step S1, obtaining a mutual capacitance measured value of the electrode array and forming a current mutual capacitance matrix; step S2, updating a reference mutual capacitance matrix based on the current mutual capacitance matrix when judging that effective touch is not present currently; Step S3, inputting a deformation deduction model based on the difference between the current mutual capacitance matrix and the reference mutual capacitance matrix to obtain deformation parameters representing the deformation of the flexible touch pad; s4, correcting a preset static coordinate mapping function according to the deformation parameters to obtain a dynamic coordinate mapping function; step S5, acquiring self-capacitance touch signals of the electrode array and performing baseline compensation based on the deformation parameters; and S6, mapping the electrode positions corresponding to the compensated self-capacitance touch signals to a virtual plane coordinate system through the dynamic coordinate mapping function, and calculating and outputting touch coordinates in the virtual plane coordinate system. As an optimal scheme of the capacitive touch pad detection method, the deformation deduction model is a parameterized model for mapping mutual capacitance difference characteristics into deformation parameters, and the deformation parameters at least comprise one of bending curvature and stretching proportion. As a preferable scheme of the capacitive touch pad detection method, the deformation parameters comprise global deformation components and local deformation components, and the local deformation components are used for representing the spatial positions and the amplitudes of wrinkles. The method for detecting the capacitive touch pad comprises the following steps that the correction static coordinate mapping function comprises nonlinear transformation of a coordinate grid according to the deformation parameters, and a mapping result of any electrode position is obtained through interpolation; The correctio