Two-point optical touch positioning method and system based on double-frequency signal

Abstract

The invention discloses a two-point optical touch positioning method and system based on a double-frequency signal, and belongs to the technical field of optical touch, the method comprises the following steps: enabling two light sources to emit optical signals carrying different frequencies, enabling the optical signals to enter an optical film through grating coupling, then propagating the optical signals to the edge of the optical film, and converting the optical signals into electric signals; signals are collected in a multi-channel signal collection mode to obtain time sequence data, the signals are distinguished according to edge number differences, coordinates of corresponding incidence points are calculated, and coordinate deviation of overlapped signals is corrected through cross check; the system comprises a double-frequency light source module, an optical conduction module, a photoelectric conversion module, a signal processing module and an output module, incident light of the double-frequency light source module is transmitted to the edge of the optical conduction module through the optical conduction module and received by the photoelectric conversion module, and the coordinate of the incident light and the coordinate of the incident light are calculated through the signal processing module. And touch interaction is realized by the output module. The anti-interference performance and the response speed of two-point touch are improved by simplifying the frequency distinguishing logic.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical touch technology, and particularly relates to a two-point optical touch positioning method and system based on a dual-frequency signal. BACKGROUND

[0002] Touch technology can be divided into resistive touch, capacitive touch, acoustic touch and optical touch. Resistive touch locates by the contact between the upper and lower two layers of conductive film to change the resistance, and realizes two-point touch by accurately identifying the voltage difference generated by the two contact points. However, it is difficult to ensure uniform pressure distribution in actual application, and two-point signal crosstalk is easily caused, resulting in positioning deviation. At the same time, the transmittance of resistive touch is low, which affects the display effect, and the response speed is slow, usually ≥100 ms, which is difficult to meet the demand of accurate and efficient interaction.

[0003] Capacitive touch works by means of the coupling capacitance formed by the human body and the screen, and calculates the coordinates on the four electrodes by the current ratio to realize two-point touch. However, this technology is extremely sensitive to environmental factors, and the fluctuations of temperature, humidity and surrounding electromagnetic interference will affect the capacitive field, resulting in a two-point recognition accuracy deviation of more than 5 mm in the edge area of the screen. In addition, non-conductors cannot form effective capacitance with the screen, and cannot trigger touch operation, which limits the use scenarios.

[0004] Acoustic touch uses an array of acoustic wave transmitters and receivers to locate according to the blocking of acoustic waves by the touch point. When realizing two-point touch, it is necessary to accurately distinguish the acoustic wave attenuation difference caused by the two blocking areas, but once the screen surface is stained with dirt, it will interfere with the propagation of acoustic waves, causing signal distortion. Especially when the distance between the two points is less than 10 mm, the system is easy to misjudge it as single-point touch, greatly reducing the recognition accuracy.

[0005] Traditional infrared optical touch relies on a dense array of infrared tubes arranged around the screen edge to locate the two-point touch position by blocking two groups of infrared beams, but this way has low resolution, generally ≥1 mm, which is difficult to realize fine operation, and the device frame needs to accommodate the infrared tubes, resulting in a wide frame, usually ≥10 mm.

[0006] The patent document with publication number CN110647257A discloses a touch screen based on dot matrix structure distribution grating, which effectively improves the overall efficiency and sensitivity of the touch screen by optimizing the dot matrix distribution of the grating, but still cannot meet the demand of two-point touch. SUMMARY

[0007] To solve the problems existing in the prior art, the present application provides a two-point optical touch positioning method and system based on a dual-frequency signal.

[0008] The technical scheme of the present application is as follows: In a first aspect, the present application provides a two-point optical touch positioning method based on a dual-frequency signal, comprising the following steps: Two light sources emit light signals carrying different frequencies, and the ratio of the number of rising edges or falling edges of the two light signals is higher than a preset value; A grating is arranged on the incident surface of the optical film, which is arranged to be able to couple the light signal into the optical film, and the light signal is propagated to the edge of the optical film after being incident on the optical film. The grating includes grating structures along the long side and the short side of the optical film; The light signal emitted from the edge of the optical film is received and converted into an electrical signal, and the signal is collected by a multi-channel signal collection method to obtain time sequence data at consecutive time points; Edge detection is performed on the time sequence data, the number of rising edges or falling edges in a single collection period is counted, and the electrical signal components corresponding to f1 and f2 are distinguished according to the number difference; According to the amplitude distribution of the detector, the coordinates of the incident points corresponding to the two frequency incident lights are calculated respectively, and when the distance between the two-point axis coordinates is less than a preset value, the coordinate deviation is corrected by cross verification.

[0009] Further, the multi-channel signal collection method includes a grouping polling mode and an external multi-ADC parallel mode; The grouping polling mode triggers the signal sampling of each group of detectors in a preset order, and the sampling time of each group is ≤1 / 2 period of the corresponding signal; When the external multi-ADC parallel mode collects signals, all external analog-to-digital converters are started synchronously, and simultaneous collection and transmission of multiple groups of signals to the main control chip are completed.

[0010] Further, the time sequence data collected continuously has a time length greater than two periods of the electrical signal.

[0011] Further, the cross verification corrects the coordinate deviation according to the amplitude attenuation difference of the dual-frequency signal, specifically including: The mixed signal is separated based on the edge sampling interval of signals with different frequencies, and the detector position corresponding to the overlapping direction of f1 and f2 signals is preliminarily determined; The initial peak position is iteratively corrected according to the difference in amplitude attenuation rate of signals with different frequencies in the optical film; The coordinates are iteratively adjusted according to the amplitude attenuation rate of adjacent detectors of the detector in the signal overlapping direction until the amplitude attenuation amplitude meets the attenuation characteristics.

[0012] In a second aspect, the present application provides a two-point optical touch positioning system based on a dual-frequency signal, comprising a dual-frequency light source module, an optical transmission module, a photoelectric conversion module, a signal processing module, and an output module; The dual-frequency light source module is used to output two incident lights with different frequencies; The optical transmission module comprises an optical film and a grating arranged on an incident surface of the optical film, the grating being used for coupling the incident light into the optical film, the incident light being transmitted to the edge of the optical film; the grating comprises grating structures with vector directions along the long side and the short side of the optical film; The photoelectric conversion module is used for receiving the optical signal emitted from the edge of the optical film and converting the optical signal into an electrical signal; The signal processing module obtains the coordinates of the incident light according to the electrical signal, and specifically comprises: The signal is collected by a multi-channel signal collection method to obtain time sequence data at continuous time points; Edge detection is performed on the time sequence data, the number of rising edges or falling edges in a single collection period is counted, and the electrical signal components corresponding to two different frequency incident lights are distinguished according to the number difference; The incident point coordinates corresponding to the two different frequency incident lights are calculated according to the detector amplitude distribution, and when the distance between the two-point axis coordinates is less than a preset value, the coordinate deviation is corrected by cross verification.

[0013] Further, the dual-frequency light source module comprises two independent light sources, which are respectively driven by the first frequency f1 electrical signal and the second frequency f2 electrical signal output by the master control chip. The frequency relationship of f1 and f2 satisfies: in the single collection period of the master control chip at the receiving end of the photoelectric conversion module, the number of rising edges or falling edges of f1 and f2 has a distinguishable difference, and the number of f1 is at least 1.5 times that of f2.

[0014] Further, the grating period matches the wavelength of the incident light, and satisfies the coupling equation:

[0015] wherein, and are the refractive indexes of air and the optical film respectively, is the incident angle of the incident light, is the wavelength of the incident light, T is the period of the grating on the surface of the optical film, is the diffraction angle of the diffracted light in the optical film.

[0016] Further, the photoelectric conversion module is a photosensitive detector array arranged at the edge of the optical film of the optical transmission module, which converts the mixed incident light signal transmitted in the waveguide of the optical film into an electrical signal containing f1 and f2; the photosensitive detector array is arranged on two adjacent sides or all four sides of the optical film.

[0017] Further, the signal processing module comprises a collection unit, a frequency distinguishing unit and a coordinate solving unit. The acquisition unit adopts a grouped polling acquisition or an external multi-analog-to-digital conversion parallel acquisition architecture; in the grouped polling acquisition, the detectors are acquired in sequence in groups; in the external multi-analog-to-digital conversion parallel acquisition, a plurality of external analog-to-digital converters are used to synchronously acquire a plurality of groups of detector signals; The frequency distinguishing unit performs edge detection on the acquired electrical signals, and distinguishes the signal components corresponding to f1 and f2 by counting the number of edges in a single acquisition period. The coordinate solving unit calculates the incident light coordinates according to the signal amplitude distribution of the detectors along the long side and the short side of the optical film.

[0018] Further, the analog-to-digital converter is of 12-bit or more accuracy, and communicates with the master control chip through a serial peripheral interface (SPI).

[0019] Further, the output module transmits the incident light coordinates to an upper computer through a communication interface such as a USB, a serial port, WiFi or Bluetooth, to realize touch interaction.

[0020] Compared with the prior art, the present application has the following advantages: The present application loads two independent light sources with different frequency driving signals, so that the incident light carries unique frequency identification; the signal components corresponding to the two frequencies are separated by an algorithm, the incident light coordinates are solved, the deviation in the overlapping area is corrected in combination with the amplitude attenuation difference, and the two-point positioning error is ≤0.5 mm; secondly, the two frequency signals are distinguished by edge counting, without the need for spectrum analysis, the operation load is reduced, but the frame processing time is ≤10 ms; finally, the dual-mode acquisition architecture of grouped polling and external multi-analog-to-digital conversion parallel acquisition adapts to the multi-detector layout, and improves the acquisition efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 It is a two-point optical touch positioning system structure based on dual-frequency signals; Figure 2 It is a two-point optical touch positioning system structure based on dual-frequency signals; Figure 3 It is a time sequence data acquisition diagram of a frequency f1=2.5 kHz signal; Figure 4 It is a time sequence data acquisition diagram of a frequency f2=8 kHz signal; Figure 5 It is a distribution situation diagram when the touch point signals are not overlapped; Figure 6 It is a time domain waveform diagram when two different frequency signals are synchronously overlapped; Figure 7 It is a time domain waveform diagram when two different frequency signals are asynchronously overlapped; Figure 8A schematic diagram of a dual-frequency modified cross-checking process; Figure 2 The reference signs in the drawings represent: 1, dual-frequency light source module; 2, optical transmission module; 3, photoelectric conversion module; 4, signal processing module; 5, output module. DETAILED DESCRIPTION

[0022] The application will be further described below in conjunction with the drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the application, and all other embodiments obtained by a person of ordinary skill in the art without creative effort based on the embodiments in the application shall fall within the protection scope of the application.

[0023] It should be understood that the terms used in the embodiments of the application are only for the purpose of describing the specific embodiments, and are not intended to limit the application. The singular forms "a", "an" and "the" used in the embodiments of the application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] The terms "comprise" and "include" indicate the presence of described features, integers, steps, operations, elements, and / or components, but do not exclude one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0025] The term "and / or" means any combination of one or more of the associated listed terms and all possible combinations thereof, and includes these combinations.

[0026] Embodiment one The embodiment provides a two-point optical touch positioning system based on dual-frequency signals, referring to Figure 1 and Figure 2 , Figure 1 A structure relationship diagram of a two-point optical touch positioning system based on dual-frequency signals provided by the embodiment, Figure 2 A structure diagram of a two-point optical touch positioning system based on dual-frequency signals provided by the embodiment.

[0027] The system comprises a dual-frequency light source module 1, an optical transmission module 2, a photoelectric conversion module 3, a signal processing module 4, and an output module 5; The dual-frequency light source module 1 is used for outputting incident light of two different frequencies; The optical transmission module 2 comprises an optical film and a grating arranged on an incident surface of the optical film, the grating is used for coupling the incident light into the optical film, and the incident light is transmitted to the edge of the optical film; the grating comprises grating structures with vector directions along the long side and the short side of the optical film; The photoelectric conversion module 3 is used for receiving the optical film edge emitted light signal and converting into an electrical signal; The signal processing module 4 obtains the coordinates of the incident light according to the electrical signal, and specifically comprises: The signal is collected by a multi-channel signal collection method to obtain time sequence data at continuous time points; The time sequence data is subjected to edge detection, the number of rising edges or falling edges in a single collection period is counted, and the electrical signal components corresponding to two different frequency incident lights are distinguished according to the number difference; The incident point coordinates corresponding to two different frequency incident lights are calculated according to the detector amplitude distribution, and when the distance between the two point axis coordinates is less than a preset value, the coordinate deviation is corrected by cross verification.

[0028] Preferably, the dual-frequency light source module 1 comprises two independent light sources driven by the first frequency f1 electrical signal and the second frequency f2 electrical signal output by the master chip respectively; The frequency relationship of f1 and f2 satisfies: in the single collection period of the master chip at the receiving end of the photoelectric conversion module 3, the number of rising edges or falling edges of the two is different and can be distinguished, f1 is at least 1.5 times of f2, and it is ensured that f1 and f2 can be distinguished by edge counting.

[0029] Preferably, the grating period is matched with the wavelength of the incident light, and the coupling equation is satisfied:

[0030] Wherein, and n1 and n2 are the refractive indexes of air and optical film respectively, θi is the incident angle of the incident light, λ is the wavelength of the incident light, T P is the period of the grating on the surface of the optical film, θd is the diffraction angle of the diffracted light in the optical film.

[0031] Preferably, the photoelectric conversion module 3 is a photosensitive detector array arranged at the edge of the optical film of the optical transmission module 2, such as a combination of infrared sensors and visible light sensors matched with the number and touch accuracy, which converts the mixed incident light signal transmitted by the waveguide in the optical film into an electrical signal containing f1 and f2.

[0032] Preferably, the signal processing module 4 is realized based on the master chip and comprises a collection unit, a frequency distinguishing unit and a coordinate solving unit; The collection unit adopts a grouped polling collection architecture or an external multi-ADC parallel collection architecture, the grouped polling collection architecture groups the detectors, such as 14 channels per group, and collects in sequence, and the external multi-ADC parallel collection architecture synchronously collects signals of multiple groups of detectors through external multiple analog-to-digital converters; The frequency distinguishing unit performs edge detection on the collected electrical signal, and distinguishes the signal components corresponding to f1 and f2 by counting the number of edges in a single collection period; The coordinate calculation unit calculates the incident light coordinates according to the signal amplitude distribution of the detector along the long side and the short side of the optical film.

[0033] Preferably, the output module 5 transmits the incident light coordinates to the upper computer through a communication interface such as USB, serial port, WiFi or Bluetooth, to realize touch interaction.

[0034] Embodiment two The embodiment provides a two-point optical touch positioning method based on a double-frequency signal, which comprises the following steps: Two light sources emit light signals carrying different frequencies, and the ratio of the number of rising edges or falling edges of the two light signals is higher than a preset value, and the preset value is greater than or equal to 1.5; A grating is arranged on the incident surface of the optical film, the grating is arranged to be capable of coupling the light signal into the optical film, the light signal is propagated to the edge of the optical film after being incident on the optical film, and the grating comprises grating structures along the long side and the short side of the optical film; The light signal emitted from the edge of the optical film is received and converted into an electrical signal, the signal is collected through a multi-channel signal collection mode, and time sequence data at continuous time points is obtained; Edge detection is performed on the time sequence data, the number of rising edges or falling edges in a single collection period is counted, and the electrical signal components corresponding to f1 and f2 are distinguished according to the number difference; According to the amplitude distribution of the detector, the incident point coordinates corresponding to the incident light of the two frequencies are calculated respectively, when the distance between the two-point axis coordinates is less than or equal to 3 mm, the coordinate deviation is corrected through the amplitude attenuation difference of the double-frequency signal; The two-point coordinates are output, and the two-point interaction functions required for scaling, dragging and double-player games are realized.

[0035] Preferably, the grouping polling mode triggers the signal sampling of each group of detectors in a preset order, and the sampling time of each group is less than or equal to 1 / 2 of the corresponding signal period. When the external multi-ADC parallel mode collects signals, all external ADCs are started synchronously, and the simultaneous collection of multiple groups of signals is completed and transmitted to the main control chip.

[0036] Preferably, the time sequence data collected continuously has a time length greater than two periods of the electrical signal.

[0037] Preferably, the cross-checking corrects the coordinate deviation according to the amplitude attenuation difference of the double-frequency signal, and specifically comprises: The edge sampling interval of the signals with different frequencies is used to separate the mixed signal, and the detector positions corresponding to the overlapping directions of the f1 and f2 signals are preliminarily determined; The initial peak position is iteratively corrected based on the difference in amplitude attenuation rate of signals of different frequencies in the optical film. The coordinates are iteratively adjusted based on the amplitude attenuation rate of adjacent detectors in the signal overlap direction detector until the amplitude attenuation meets the attenuation characteristics.

[0038] Example 3 This embodiment provides a two-point optical touch positioning method based on dual-frequency signals, including the following steps: The dual-frequency light source uses a microcontroller to output square waves to drive the laser tube. The square wave frequencies are f1 = 2.5 kHz and f2 = 8 kHz. Figure 3 As shown, the f1 time-domain waveform contains two rising edges within 1 ms, as follows: Figure 4 As shown, the f2 time-domain waveform contains 8 rising edges within 1 ms; The optical signals driven by f1 and f2 are coupled into a polycarbonate (PC) optical film with a refractive index of n=1.58 through a grating, and then waveguided along the long and short sides to the edge of the optical film. The detector at the edge of the optical film continuously samples at a fixed frequency of 20kHz to obtain timing data containing complete waveforms. When the optical signals driven by f1 and f2 do not overlap, the acquired signal is as follows. Figure 5 As shown; Analyzing the timing data, fewer than 4 rising edges within 1ms indicate an f1 driving optical signal, while more than 4 indicate an f2 driving optical signal. The detector outputs a continuous voltage sequence, which is compared using a threshold. For example, a voltage jump from below 1.5V to above 1.5V is considered a rising edge, and the sampling point index for each rising edge is recorded. Taking the incident point A of the f1 driving signal as an example, the calculation process of the horizontal coordinate x1 along the long side of the optical film is as follows: When point A is touched, the horizontal detector H at that point... k and the adjacent detector H k-2 H k-1 H k+1 and H k+2 Generate a response, where H k The amplitude is the largest, and x1 is calculated using a quadratic interpolation algorithm:

[0039] in k For the maximum amplitude detector H k The serial number, A The calculation accuracy is 0.1 mm for the corresponding amplitude. Similarly, the vertical coordinate y1 of the incident point A along the short side of the optical film passes through the vertical detector V at that point. k and adjacent detector V k-2 V k-2 V k+1And V k+2 The amplitude of the y1 is calculated by a quadratic interpolation algorithm, and the final A point coordinate is (x1, y1).

[0040] Embodiment Four The embodiment provides a two-point optical touch positioning method based on a dual-frequency signal, and comprises the following steps: The dual-frequency light source is driven by a single-chip microcomputer to output f1=2.5 kHz and f2=8 kHz square waves, wherein 1 ms in the f1 time domain waveform contains three rising edges, and 1 ms in the f2 time domain waveform contains eight rising edges; The light signals driven by f1 and f2 are coupled into a PC optical film with a refractive index of n=1.58 through a grating, and are guided to the edges of the optical film along the long and short directions; The detectors at the edges of the optical film continuously sample at a frequency of 20 kHz to obtain time sequence data containing complete waveforms, and when the light signals driven by f1 and f2 overlap, the time sequence data waveforms are superimposed; When the light signals driven by f1 and f2 and the acquisition end of the detector are synchronously controlled, the time sequence data waveform received by the maximum amplitude detector on one side of the optical film is as shown in Figure 6 , which indicates that the light signals driven by f1 and f2 overlap in this axial direction, and two types of combined waveforms will appear in one acquisition cycle, and the two types of combined waveforms have a periodic repetition characteristic in multiple cycles, and the period is the minimum common multiple of the periods corresponding to the frequencies f1 and f2, wherein: The minimum value of the first type of combined waveform is the same as the maximum value of a single signal, and the maximum value is the sum of the maximum values of the two signals, corresponding to the superposition state of the high level of the f1 signal and the high level of the f2 signal; The minimum value of the second type of combined waveform is 0, corresponding to the superposition state of the low level of the f1 signal and the low level of the f2 signal; and the maximum value is the same as the maximum value of a single signal, corresponding to the superposition state of the high level of the f1 signal and the low level of the f2 signal or the superposition state of the low level of the f1 signal and the high level of the f2 signal; The overlapping signals are cross-checked, and the coordinate deviation is corrected, and the correction process is as shown in Figure 8 . Taking the actual arrangement interval of the detector as 1 mm as an example, when the distance between the f1 driving signal incident point A and the f2 driving signal incident point B is ≤5 mm, the A coordinate is set as (50, 60), the B coordinate is set as (53, 62), the overlapping area signal involves 5-7 consecutive detectors at each edge of the optical film, and in the horizontal direction, H 48 ~H 54 , and in the vertical direction, V 58 ~V 64 . When the A point horizontal coordinate x1 is solved alone, the A point is in H 50The amplitude of f1 is lower due to the superposition of the f2 signal at point B, causing the actual coordinate at 50mm to be misjudged as 51mm; when calculating the horizontal coordinate x2 of point B separately, point B is at H 53 The amplitude of f2 is too high due to the superposition of the f1 signal at point A, which causes the actual coordinate at 53mm to be misjudged as 52.5mm.

[0041] To correct for coordinate bias, f1 and f2 are separated from the mixing edge. Assuming a sampling rate of 20kHz and an interval T between each sampling point... s =50μs, for f1, an edge occurs once every 8 sampling points, and for f2, an edge occurs once every 2.5 sampling points. Based on the sampling point index of each rising edge recorded in Example 3, the edge index is differentiated to obtain the sampling point interval Δ between adjacent edges. d , will Δ d The edges between 2 and 3 are classified as the f2 sequence, corresponding to the 8kHz transition; Δ d The edge at =8 is assigned to the f1 sequence, corresponding to a 2.5kHz transition. Simultaneously, the initial peak value x1 of f1 is determined at H by amplitude comparison. 51 Nearby, the initial peak value of f2, x2, is at H. 52 nearby.

[0042] Dual-frequency attenuation difference correction is performed. In PC optical films, the higher the frequency, the faster the signal attenuates. For the high-frequency f2, attenuation is even faster in PC films. H is extracted. 52 Adjacent detector H 53 The amplitude of f2, if H 53 The f2 amplitude is only slightly larger than H. 52 The 20% decrease, slower than the expected high-frequency decay, indicates that the actual peak value of f2 is closer to H. 53 x2 will be directed to H 53 Make minor adjustments to the direction until H 53 The amplitude reduction of f2 is ≥50%, which conforms to the characteristics of high-frequency rapid attenuation.

[0043] For low-frequency f1, attenuation is slower in PC films. Extract H... 51 Adjacent detector H 50 The amplitude of f1, if H 50 The f1 amplitude is only slightly larger than H. 51 The 60% reduction, faster than the expected low-frequency decay, indicates that the actual peak value of f1 is closer to H. 52 x1 to H 52 Make minor adjustments to the direction until H 50 The amplitude reduction of f1 is ≤30%, which conforms to the slow attenuation characteristics of low frequency.

[0044] After the iterative correction, the amplitude of f2 in the overlap region approaches zero, and the amplitude of f1 in the overlap region remains at a high level, so that the coordinate deviation correction in the overlap region is finally realized, and the accuracy is improved from 1mm in single frequency solution to 0.1mm.

[0045] Embodiment five The embodiment provides a two-point optical touch positioning method based on dual-frequency signals, and comprises the following steps: The dual-frequency light source is driven by a single-chip microcomputer to output f1=2.5kHz and f2=8kHz square waves, wherein the f1 time-domain waveform contains three rising edges within 1ms, and the f2 time-domain waveform contains eight rising edges within 1ms; The light signals driven by f1 and f2 are coupled into a PC optical film with a refractive index of n=1.58 through a grating, and are guided to the edge of the optical film along the long side and the short side; The detector at the edge of the optical film continuously samples at a frequency of 20kHz to obtain time sequence data containing complete waveforms, and when the light signals driven by f1 and f2 overlap, the time sequence data waveforms are superimposed; In order to simplify the system, the light signals driven by f1 and f2 are not synchronized, and the time sequence data waveform received by the maximum amplitude detector on one side of the optical film is as shown in Figure 7 The starting point of the superimposed signal is not the beginning of the respective signal period, and the time sequence data analysis and the coordinate deviation correction method refer to embodiment four.

Claims

1. A two-point optical touch positioning method based on a dual-frequency signal, characterized in that, The method comprises the following steps: Two light sources emit light signals carrying different frequencies, and the ratio of the number of rising edges or falling edges of the two light signals is higher than a preset value; A grating is arranged on the incident surface of the optical film, and the grating is arranged to be capable of coupling the light signals into the optical film, the light signals are transmitted to the edge of the optical film after being incident on the optical film, and the grating comprises grating structures with vector directions along the long side and the short side of the optical film; The light-sensitive detector array receives the light signals emitted from the edge of the optical film and converts them into electrical signals, acquires time sequence data at continuous time points through a multi-channel signal acquisition mode, and obtains the time sequence data; Edge detection is performed on the time sequence data, the number of rising edges or falling edges in a single acquisition period is counted, and the electrical signal components corresponding to f1 and f2 are distinguished according to the number difference; The incident point coordinates corresponding to the light of the two frequencies are respectively calculated according to the amplitude distribution of the detector, and when the distance between the two point axis coordinates is less than a preset value, the coordinate deviation of the overlapping signal is corrected through cross verification. 2.The two-point optical touch positioning method based on dual-frequency signals according to claim 1, wherein, The multi-channel signal acquisition mode comprises a grouping polling mode and an external multi-ADC parallel mode; The grouping polling mode triggers the signal sampling of each group of detectors in a preset order, and the sampling time of each group is less than 1 / 2 of the period of the corresponding electrical signal; When the external multi-ADC parallel mode acquires signals, all external analog-to-digital converters are started synchronously, and multiple groups of signals are acquired and transmitted to the main control chip at the same time. 3.The two-point optical touch positioning method based on dual-frequency signals according to claim 1, wherein, The time length of the time sequence data acquired continuously when the signals are acquired is greater than two periods of the electrical signal.

4. The two-point optical touch positioning method based on dual-frequency signals according to claim 1, characterized in that, The cross verification corrects the coordinate deviation according to the amplitude attenuation difference of the double-frequency signal, and specifically comprises: The mixed signal is separated based on the edge sampling interval of the signals of different frequencies, and the detector positions corresponding to the overlapping directions of the f1 and f2 signals are preliminarily determined; The initial peak position is iteratively corrected according to the amplitude attenuation rate difference of the signals of different frequencies in the optical film; The coordinate is iteratively adjusted according to the amplitude attenuation rate of the adjacent detectors of the detector in the signal overlapping direction, until the amplitude attenuation amplitude meets the attenuation characteristics.

5. A two-point optical touch positioning system based on dual-frequency signals, characterized in that, The method comprises a double-frequency light source module, an optical transmission module, an optoelectronic conversion module, a signal processing module, and an output module; The double-frequency light source module is used to output two incident lights of different frequencies; The optical transmission module comprises an optical film and a grating arranged on the incident surface of the optical film, the grating is used to couple the incident light into the optical film, and the incident light is transmitted to the edge of the optical film; the grating comprises grating structures with vector directions along the long side and the short side of the optical film; The optoelectronic conversion module is used to receive the light signals emitted from the edge of the optical film and convert them into electrical signals; The signal processing module obtains the coordinates of the incident light according to the electrical signals, and specifically comprises: Signals are acquired through a multi-channel signal acquisition mode to obtain time sequence data at continuous time points; Edge detection is performed on the time sequence data, the number of rising edges or falling edges in a single acquisition period is counted, and the electrical signal components corresponding to the two different frequency incident lights are distinguished according to the number difference; The incident point coordinates corresponding to the two different frequency incident lights are respectively calculated according to the amplitude distribution of the detector, and when the distance between the two point axis coordinates is less than a preset value, the coordinate deviation is corrected through cross verification.

6. The two-point optical touch positioning system based on dual-frequency signals according to claim 5, characterized in that, The dual-frequency light source module comprises two independent light sources, which are respectively driven by the first frequency f1 electrical signal and the second frequency f2 electrical signal output by the master chip; The frequency relationship of f1 and f2 satisfies: in the single collection cycle of the master chip at the receiving end of the photoelectric conversion module, there is a distinguishable difference in the number of rising edges or falling edges of f1 and f2, and the f1 electrical signal is at least 1.5 times the f2 electrical signal.

7. The two-point optical touch positioning system based on dual-frequency signals according to claim 5, characterized in that, The grating period matches the wavelength of the incident light, satisfying the coupling equation: wherein, and nairand nfilmare the refractive indices of air and the optical film, respectively, θiis the angle of incidence of the incident light, λis the wavelength of the incident light, T Λis the period of the surface grating of the optical film, θdis the diffraction angle of the diffracted light within the optical film.

8. The two-point optical touch positioning system based on dual-frequency signals according to claim 5, characterized in that, The photoelectric conversion module is a photosensitive detector array arranged at the edge of the optical film of the optical transmission module, which converts the mixed incident light signal transmitted by the waveguide in the optical film into an electrical signal containing f1 and f2.

9. The two-point optical touch positioning system based on dual-frequency signals according to claim 5, characterized in that, The signal processing module includes an acquisition unit, a frequency distinguishing unit and a coordinate solving unit; The acquisition unit adopts a grouped polling acquisition or an external multi-ADC parallel acquisition architecture; The grouped polling acquisition architecture acquires the signals of the detectors in sequence by grouping; The external multi-ADC parallel acquisition architecture synchronously acquires the signals of multiple groups of detectors through multiple external ADCs; The frequency distinguishing unit detects the edges of the collected electrical signals, and distinguishes the signal components corresponding to f1 and f2 by counting the number of edges in a single collection cycle; 10. The two-point optical touch positioning system based on dual-frequency signals according to claim 5, characterized in that, The coordinate solving unit calculates the incident light coordinates according to the signal amplitude distribution of the detectors along the long side and short side of the optical film. The output module transmits the incident light coordinates to the host computer through a communication interface such as USB, serial port, WiFi or Bluetooth, realizing touch interaction.

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