CN112068737B - Infrared touch screen signal conditioning circuit and method - Google Patents
Infrared touch screen signal conditioning circuit and method Download PDFInfo
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F3/00—Input arrangements for transferring data to be processed into a form capable of being handled by the computer; Output arrangements for transferring data from processing unit to output unit, e.g. interface arrangements
- G06F3/01—Input arrangements or combined input and output arrangements for interaction between user and computer
- G06F3/03—Arrangements for converting the position or the displacement of a member into a coded form
- G06F3/041—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
- G06F3/042—Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means by opto-electronic means
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Abstract
The application discloses an infrared touch screen signal conditioning circuit and method, through after receiving useful signals, control charge-discharge circuit is in advance obtained useful signals's initial time charges, still be used for control charge-discharge circuit is in advance obtained useful signals's crest moment carries out the earth discharge to direct the influence that the signal attenuation that the discharge of collecting in advance produced outside produced, and then avoid useful signals and interference signal superposition produced influences, solve the problem that low frequency interference signal and the interference signal of same or similar frequency carry out the interference to infrared touch screen's touch action normal identification, can satisfy many infrared touch screens and use side by side to can adapt to the environment that has the interference source, anti-interference ability has been improved.
Description
Technical Field
The application relates to the technical field of infrared signal processing, in particular to an infrared touch screen signal conditioning circuit and a corresponding conditioning method.
Background
As shown in FIG. 1, the infrared touch screen is provided with an infrared emission tube and a photosensitive tube, and emits infrared rays to the photosensitive tube through the infrared emission tube, so that infrared rays are formed, a plurality of infrared emission tubes emit infrared rays to a plurality of photosensitive tubes, a dense infrared optical network is formed on the surface of the whole touch screen, meanwhile, the photosensitive tube receives the infrared rays and then converts the infrared rays into electric signals through photoelectric conversion, and then digital signals are finally recognized by the MCU through A/D conversion after signal amplification, and when an opaque object shields the infrared rays on the surface of the touch screen, the MCU can recognize that the object is shielded, and meanwhile, the MCU calculates the coordinate output of the touch object according to the relative position of the missing rays, so that touch control actions are completed.
At present, the actual problem of the infrared touch screen is that when two infrared touch screens are placed side by side and the relative angle is smaller than 180 degrees, signals of the two infrared touch screens are mutually interfered, for example, light of an emitting tube of one infrared touch screen is emitted onto a photosensitive tube of the other infrared touch screen, so that signal identification disorder can occur to an MCU, touch control actions can not be correctly completed, or when an interference source with the frequency close to the working frequency of the infrared touch screen exists, normal work of the infrared touch screen can be influenced, and the MCU can not correctly identify the touch actions.
The two practical problems are interference belonging to the same frequency or similar frequency, and are shown in a waveform timing diagram in fig. 2 under the condition of representing the normal working signal of the infrared touch screen, wherein the signal is in a sine wave form in each signal period due to the charge and discharge of a capacitor in the circuit, and has wave crests and wave troughs; when the interference sources with the same frequency are connected with the near infrared touch screen, the first situation is that the signal waveform time sequence shown in the figure 3 is shown as working signals with the same frequency and different time domains by even half periods, namely wave crests are overlapped with each other, and wave troughs are overlapped with each other, so that the working signals are enhanced; the second case occurs when the waveform timing of the signal, as shown in fig. 4, represents the working signals that differ by an odd number of half cycles in the same frequency domain, i.e., the peaks and valleys are superimposed, so that the working signals cancel each other. The two interference conditions can influence the normal operation of the infrared touch screen, the MCU can not correctly recognize the touch action, and in practical application, an interference source with similar frequency is connected with the near infrared touch screen, the signal time sequence of the interference source is between the normal operation signal of the infrared touch screen and the operation signal which is different from the same frequency time domain by odd half periods, and the MCU can be affected to correctly recognize the touch action.
Aiming at the interference problem, the existing circuit can not solve the problem, and can only change the structure of the infrared touch screen, thereby realizing shielding of interference signals, such as that the photosensitive tubes shrink into the structure or the relative angle of the photosensitive tubes is larger than 180 degrees when the parallel infrared touch screens are placed, and the like. However, the above changes to the structure may make the structure inflexible, resulting in poor user experience.
The Chinese patent publication No. CN101893968 discloses an infrared touch screen signal processing circuit, which comprises a signal receiving circuit, a microcontroller and a high-pass filter circuit, wherein the high-pass filter circuit comprises a capacitor and a grounded analog switch, the analog switch can be controlled by the microcontroller to be closed so as to filter out an ambient light signal, but it is understood that the frequency of the ambient light signal is lower than that of the infrared touch screen, and the method removes a low-frequency interference signal through the high-pass filter circuit, but for the interference signal with the same or similar frequency as the infrared touch screen, the interference signal cannot be filtered out, so that the MCU is influenced to correctly identify the touch action.
Disclosure of Invention
The application provides a signal conditioning circuit and a signal conditioning method for an infrared touch screen, which are used for solving the technical problem that the conventional low-frequency interference signals and interference signals with the same or similar frequency interfere with the normal identification of the touch action of the infrared touch screen.
In view of this, the first aspect of the present application provides an infrared touch screen signal conditioning circuit, the infrared touch screen including an infrared emitting tube, comprising: the device comprises a photosensitive signal acquisition unit, a charge-discharge circuit and an MCU;
the input end of the charge-discharge circuit is electrically connected with the output end of the photosensitive signal acquisition unit, the first output end of the charge-discharge circuit is electrically connected with the input end of the MCU, and the second output end of the charge-discharge circuit is grounded;
the photosensitive signal acquisition unit is used for acquiring useful signals generated by the infrared emission tube and transmitting the useful signals to the MCU through the charge-discharge circuit;
the MCU is used for controlling the charge-discharge circuit to charge at the initial moment of the useful signal acquired in advance after receiving the useful signal acquired by the photosensitive signal acquisition unit, and is also used for controlling the charge-discharge circuit to perform grounding discharge at the peak moment of the useful signal acquired in advance, so that all signals acquired in advance by the photosensitive signal acquisition unit are released.
Preferably, the MCU is further configured to obtain a useful signal attenuation value at a peak time of the pre-obtained useful signal, and further configured to determine whether to generate a touch signal by comparing the useful signal attenuation value with a preset useful signal attenuation threshold, and specifically includes: and when the useful signal attenuation value is larger than the preset useful signal attenuation threshold value, judging that a touch signal is generated.
Preferably, the charge-discharge circuit comprises a blocking capacitor and an analog switch, the output end of the photosensitive signal acquisition unit is electrically connected with the input end of the blocking capacitor, the output end of the blocking capacitor is electrically connected with the input end of the MCU, the analog switch is electrically connected with a connecting node between the blocking capacitor and the MCU, the other end of the analog switch is grounded, and the control end of the analog switch is electrically connected with the output end of the MCU.
Preferably, an amplifier and an a/D converter are further arranged between the blocking capacitor and the MCU, the output end of the blocking capacitor is electrically connected with the input end of the amplifier, the output end of the amplifier is electrically connected with the input end of the a/D converter, and the output end of the a/D converter is electrically connected with the input end of the MCU.
Preferably, the infrared touch screen signal conditioning circuit further comprises an acquisition module, configured to acquire a signal period of the useful signal, so as to acquire a start time of the useful signal and a peak time of the useful signal.
Preferably, the acquisition module employs an oscilloscope.
On the other hand, the embodiment of the application also provides an infrared touch screen signal conditioning method, which comprises the following steps:
step one: receiving useful signals generated by the infrared touch screen;
step two: and discharging all the pre-acquired signals by charging at the initial moment of the pre-acquired useful signals and performing grounding discharge at the peak moment of the pre-acquired useful signals.
Preferably, the second step further includes: acquiring a useful signal attenuation value at a peak time of the useful signal obtained in advance, and judging whether a touch signal is generated or not by comparing the useful signal attenuation value with a preset useful signal attenuation threshold value, wherein the method specifically comprises the following steps: and when the useful signal attenuation value is larger than the preset useful signal attenuation threshold value, judging that a touch signal is generated.
Preferably, the step one further includes: and acquiring the signal period of the useful signal through an oscilloscope, thereby acquiring the starting time of the useful signal and the wave crest time of the useful signal.
From the above technical solutions, the embodiments of the present application have the following advantages:
according to the signal conditioning circuit of the infrared touch screen, after the useful signals are received, the charging and discharging circuit is controlled to charge at the initial moment of the useful signals obtained in advance, and the signal conditioning circuit is further used for controlling the charging and discharging circuit to conduct grounding discharge at the peak moment of the useful signals obtained in advance, so that all signals generated in the outside collected in advance are directly discharged, the influence caused by signal attenuation generated by superposition of interference signals and the useful signals is avoided, the problem that the low-frequency interference signals and the interference signals with the same or similar frequencies interfere with normal identification of the touch actions of the infrared touch screen is solved, the condition that a plurality of infrared touch screens are used side by side can be met, the environment with interference sources can be adapted, and the anti-interference capability is improved. The signal conditioning method of the infrared touch screen provided by the embodiment of the application has the same beneficial effects as those of the embodiment.
Drawings
FIG. 1 is a schematic diagram of an infrared touch screen in the prior art of the present application;
FIG. 2 is a waveform timing diagram of the normal operation signal of the infrared touch screen in the prior art of the present application;
FIG. 3 is a waveform timing chart of signals of the infrared touch screen and the interference signal of the prior art in the application, which are different by even half periods in the same frequency domain;
FIG. 4 is a waveform timing chart of signals differing by an odd number of half cycles in the same frequency domain of an infrared touch screen and an interference signal in the prior art of the present application;
fig. 5 is a schematic structural diagram of an infrared touch screen signal conditioning circuit according to an embodiment of the present application;
fig. 6 is a waveform timing chart of useful signals in an infrared touch screen signal conditioning circuit according to an embodiment of the present application;
fig. 7 is another schematic structural diagram of an infrared touch screen signal conditioning circuit according to an embodiment of the present application;
fig. 8 is a flowchart of a method for conditioning an infrared touch screen signal according to an embodiment of the present application;
fig. 9 is another flowchart of an infrared touch screen signal conditioning method according to an embodiment of the present application.
Detailed Description
In order to make the present application solution better understood by those skilled in the art, the following description will clearly and completely describe the technical solution in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
For easy understanding, please refer to fig. 5, an infrared touch screen signal conditioning circuit provided in this embodiment, the infrared touch screen includes an infrared transmitting tube, including: the photosensitive signal acquisition unit 1, the charge-discharge circuit 2 and the MCU3;
the input end of the charge-discharge circuit 2 is electrically connected with the output end of the photosensitive signal acquisition unit 1, the first output end of the charge-discharge circuit 2 is electrically connected with the input end of the MCU3, and the second output end of the charge-discharge circuit 2 is grounded;
the photosensitive signal acquisition unit 1 is used for acquiring useful signals generated by the infrared emission tube and transmitting the useful signals to the MCU3 through the charge-discharge circuit 2;
it should be noted that, the photosensitive signal acquisition unit 1 preferably employs a photosensitive tube or a photosensitive collector, and the useful signal generated by the infrared touch screen is a sinusoidal periodic signal.
The MCU3 is used for controlling the charge-discharge circuit 2 to charge at the initial moment of the pre-obtained useful signal after receiving the useful signal collected by the photosensitive signal collection unit 1, and is also used for controlling the charge-discharge circuit 2 to perform grounding discharge at the peak moment of the pre-obtained useful signal, so that all the signals collected by the photosensitive signal collection unit 1 are released.
It will be appreciated that all signals include both the desired signal and the interfering signal, while in this embodiment the interfering signal includes an externally generated low frequency signal as well as an interfering signal having the same or similar frequency as the desired signal.
It should be noted that, the photosensitive signal acquisition unit receives the useful signal generated by the infrared touch screen, and can determine whether a touch signal occurs according to the signal attenuation value generated by the useful signal. When there is an interference of infrared signals or other light source signals outside, the signals are also collected by the photosensitive signal collecting unit, and the interference signals are randomly generated and are not controllable, so that the interference signals can possibly enter at any time of the signal period of the useful signals, and the processing condition of the subsequent useful signals is affected. In particular, for interfering signals of the same frequency as the useful signal, this can particularly affect the processing of the useful signal.
In this embodiment, as shown in fig. 6, a waveform timing chart of a useful signal is shown, wherein in a signal period of a first useful signal, a power supply is turned on at time t0, a charge-discharge circuit starts to charge until time t1 is a peak, and the charge-discharge circuit is controlled to discharge at a voltage of 0V so that an interference signal starts to discharge at time t 1; and when the starting time t0 'of the signal period of the second useful signal starts to charge, and when the peak time t 1' starts to charge, the ground discharge is started, namely the rapid ground discharge is performed after the charging reaches the peak value, and the like, and the charge and the discharge are circulated in the signal period of each useful signal, so that all the signals collected at any time can be discharged, the interference signals and the useful signals do not generate peaks and troughs, and further, the influence caused by signal attenuation generated by the superposition of the interference signals and the useful signals is avoided, wherein the superposition of the interference signals and the useful signals is such as the superposition of the peaks, the superposition of the troughs or the superposition of the peaks and the troughs of the two signals.
In addition, when the infrared touch screen is not shielded or is not touched, signal attenuation is not generated, and the judgment of no touch is not influenced naturally.
When the infrared touch screen is shielded or touched, the touch signal brings larger amplitude signal attenuation, although the interference signal generates superposition signals to useful signals, a certain signal value can be improved, when the interference signal is an external interference source and is much weaker than the touch signal, the signal attenuation condition is still presented on the overall signal value, and the overall signal attenuation value can be judged as the touch signal as long as the overall signal attenuation value is larger than a preset attenuation threshold value, so that the interference signal does not influence the MCU to judge the touch signal, the problem of interference sources with similar frequency is solved, the parallel use of a plurality of infrared touch screens can be met, the environment with the interference sources can be adapted, and the anti-interference capability is improved.
The above is one embodiment of an infrared touch screen signal conditioning circuit provided in the present application, and the following is another embodiment of an infrared touch screen signal conditioning circuit provided in the present application.
For easy understanding, please refer to fig. 7, an infrared touch screen signal conditioning circuit provided in this embodiment, the infrared touch screen includes an infrared transmitting tube, including: the photosensitive signal acquisition unit 1, the charge-discharge circuit 2 and the MCU3;
the input end of the charge-discharge circuit 2 is electrically connected with the output end of the photosensitive signal acquisition unit 1, the first output end of the charge-discharge circuit 2 is electrically connected with the input end of the MCU3, and the second output end of the charge-discharge circuit 2 is grounded;
the photosensitive signal acquisition unit 1 is used for acquiring useful signals generated by the infrared emission tube and transmitting the useful signals to the MCU3 through the charge-discharge circuit 2;
it should be noted that, the photosensitive signal acquisition unit 1 preferably employs a photosensitive tube or a photosensitive collector, and the useful signal generated by the infrared touch screen is a sinusoidal periodic signal.
The MCU3 is used for controlling the charge-discharge circuit 2 to charge at the initial moment of the pre-obtained useful signal after receiving the useful signal collected by the photosensitive signal collection unit 1, and is also used for controlling the charge-discharge circuit 2 to perform grounding discharge at the peak moment of the pre-obtained useful signal, so that all the signals collected by the photosensitive signal collection unit 1 are released.
Further, the MCU3 is further configured to obtain a useful signal attenuation value at a peak time of the pre-obtained useful signal, and determine whether to generate the touch signal by comparing the useful signal attenuation value with a preset useful signal attenuation threshold, and specifically includes: when the useful signal attenuation value is greater than a preset useful signal attenuation threshold, it is determined that a touch signal is generated.
It should be noted that, at the peak time of the useful signal, the peak time is the highest value of the useful signal, and the touch signal is determined more accurately by acquiring the corresponding useful signal attenuation value.
Further, the charge-discharge circuit 2 includes a blocking capacitor 20 and an analog switch 21, the output end of the photosensitive signal acquisition unit 1 is electrically connected with the input end of the blocking capacitor 20, the output end of the blocking capacitor 20 is electrically connected with the input end of the MCU3, the analog switch 21 is electrically connected with a connection node between the blocking capacitor 20 and the MCU3, the other end of the analog switch 21 is grounded (0V), and the control end of the analog switch 21 is electrically connected with the output end of the MCU 3.
It should be noted that, the charge-discharge circuit 2 is formed by the blocking capacitor 20 and the analog switch 21, which has simple structure and low cost, and the blocking capacitor 20 and the analog switch 21 cooperate to filter out low-frequency interference signals, so that the charge-discharge control only performs charge-discharge control on the interference signals with the same or similar frequency as the useful signals, thereby making the touch recognition more accurate.
In this embodiment, the interference signal includes a low frequency signal and an interference signal having the same or similar frequency as the useful signal.
Further, as shown in fig. 7, an amplifier 22 and an a/D converter 23 are further disposed between the dc blocking capacitor 20 and the MCU3, an output end of the dc blocking capacitor 20 is electrically connected to an input end of the amplifier 22, an output end of the amplifier 22 is electrically connected to an input end of the a/D converter 23, and an output end of the a/D converter 23 is electrically connected to an input end of the MCU 3.
The useful signal obtained by filtering out the low-frequency interference signal is transmitted through the amplifier 22 and the a/D converter 23, so that the detection accuracy of the MCU3 on the useful signal can be improved, and the accuracy of touch recognition can be further improved.
Further, the infrared touch screen signal conditioning circuit further comprises an acquisition module, wherein the acquisition module is used for acquiring the signal period of the useful signal, so as to acquire the starting time of the useful signal and the peak time of the useful signal.
Further, the acquisition module employs an oscilloscope.
The above is another embodiment of an infrared touch screen signal conditioning circuit provided in the present application, and the following is an embodiment of an infrared touch screen signal conditioning method provided in the present application.
For easy understanding, please refer to fig. 8, the method for conditioning an infrared touch screen signal provided in this embodiment includes the following steps:
step one: receiving useful signals generated by the infrared touch screen;
step two: all the signals acquired in advance are discharged by charging at the initial moment of the useful signal acquired in advance and performing grounding discharge at the peak moment of the useful signal acquired in advance.
The receiving of the useful signal generated by the infrared touch screen may determine whether a touch signal is generated according to a signal attenuation value generated by the useful signal. When there is interference of infrared signal or other light source signal, the interference signal is received randomly, and is not controllable, so that the interference signal may enter at any time of the signal period of the useful signal, which affects the processing condition of the subsequent useful signal. In particular, for interfering signals of the same frequency as the useful signal, this can particularly affect the processing of the useful signal.
In this embodiment, as shown in fig. 6, a waveform timing chart of a useful signal is shown, wherein in a signal period of a first useful signal, a power supply is turned on at time t0, a charge-discharge circuit starts to charge until time t1 is a peak, and the charge-discharge circuit is controlled to discharge at a voltage of 0V so that an interference signal starts to discharge at time t 1; and when the starting time t0 'of the signal period of the second useful signal starts to charge, and when the peak time t 1' starts to charge, the ground discharge is started, namely the rapid ground discharge is performed after the charging reaches the peak value, and the like, and the charge and the discharge are circulated in the signal period of each useful signal, so that all the signals collected at any time can be discharged, the interference signals and the useful signals do not generate peaks and troughs, and further, the influence caused by signal attenuation generated by the superposition of the interference signals and the useful signals is avoided, wherein the superposition of the interference signals and the useful signals is such as the superposition of the peaks, the superposition of the troughs or the superposition of the peaks and the troughs of the two signals.
In addition, when the infrared touch screen is not shielded or is not touched, signal attenuation is not generated, and the judgment of no touch is not influenced naturally.
When the infrared touch screen is shielded or touched, the touch signal brings larger amplitude signal attenuation, although the interference signal generates superposition signals to useful signals, a certain signal value can be improved, when the interference signal is an external interference source and is much weaker than the touch signal, the signal attenuation condition is still presented on the overall signal value, and the overall signal attenuation value can be judged as the touch signal as long as the overall signal attenuation value is larger than a preset attenuation threshold value, so that the interference signal does not influence the judgment of the touch signal, the problem of the interference sources with similar frequency is solved, the parallel use of a plurality of infrared touch screens can be met, the environment with the interference sources can be adapted, and the anti-interference capability is improved.
Further, the step one is preceded by: and acquiring the signal period of the useful signal through the oscilloscope, thereby acquiring the starting time of the useful signal and the peak time of the useful signal.
The above is one embodiment of an infrared touch screen signal conditioning method provided in the present application, and the following is another embodiment of an infrared touch screen signal conditioning method provided in the present application.
For easy understanding, please refer to fig. 9, the method for conditioning an infrared touch screen signal provided in this embodiment includes the following steps:
step one: receiving useful signals generated by the infrared touch screen;
step two: charging at the initial moment of the pre-acquired useful signal, and performing grounding discharge at the peak moment of the pre-acquired useful signal, so as to discharge all pre-acquired signals;
step three: acquiring a useful signal attenuation value at a peak time of a pre-acquired useful signal, and judging whether a touch signal is generated or not by comparing the useful signal attenuation value with a preset useful signal attenuation threshold value, wherein the method specifically comprises the following steps of: when the useful signal attenuation value is greater than a preset useful signal attenuation threshold, it is determined that a touch signal is generated.
Further, the step one is preceded by: and acquiring the signal period of the useful signal through the oscilloscope, thereby acquiring the starting time of the useful signal and the peak time of the useful signal.
In one example, the signal value of the useful signal at the peak time is V1, and the interference signal is V2, then the superimposed signal value v3=v1+v2 after the superimposition is used, and in the process of use, the touch shielding is to shield the useful signal, that is, the useful signal attenuation value is the ratio of the current superimposed signal value V3 to the initial useful signal V1, in addition, the preset useful signal attenuation threshold is set according to the signal-to-noise ratio, and a value greater than the signal-to-noise ratio is set, and it is generally determined that the touch signal is generated by setting the preset useful signal attenuation threshold to 70%, that is, the signal attenuation value exceeds 70%, and in addition, since the interference signal is caused by an external interference source, compared with the touch signal, the touch signal is much weaker, and therefore, the determination of the touch signal is not affected.
In the several embodiments provided in this application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.
The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.
In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit. The integrated units may be implemented in hardware or in software functional units.
The integrated units, if implemented in the form of software functional units and sold or used as stand-alone products, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be embodied in essence or a part contributing to the prior art or all or part of the technical solution in the form of a software product stored in a storage medium, including several instructions to execute all or part of the steps of the methods described in the embodiments of the present application by a computer device (which may be a personal computer, a server, or a network device, etc.). And the aforementioned storage medium includes: u disk, mobile hard disk, read-Only Memory (ROM), random access Memory (Random Access Memory, RAM), magnetic disk or optical disk, etc.
The above embodiments are merely for illustrating the technical solution of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the corresponding technical solutions.
Claims (7)
1. An infrared touch screen signal conditioning circuit, the infrared touch screen including an infrared transmitting tube, comprising: the device comprises a photosensitive signal acquisition unit, a charge-discharge circuit and an MCU;
the input end of the charge-discharge circuit is electrically connected with the output end of the photosensitive signal acquisition unit, the first output end of the charge-discharge circuit is electrically connected with the input end of the MCU, and the second output end of the charge-discharge circuit is grounded;
the photosensitive signal acquisition unit is used for acquiring useful signals generated by the infrared emission tube and transmitting the useful signals to the MCU through the charge-discharge circuit;
the MCU is used for controlling the charge-discharge circuit to charge at the initial moment of the useful signal acquired in advance after receiving the useful signal acquired by the photosensitive signal acquisition unit, and is also used for controlling the charge-discharge circuit to perform grounding discharge at the peak moment of the useful signal acquired in advance, so that all signals acquired in advance by the photosensitive signal acquisition unit are released, wherein all signals comprise useful signals and interference signals, and the interference signals comprise externally generated low-frequency signals and interference signals with the same frequency as the useful signals;
the MCU is further used for acquiring a useful signal attenuation value at the peak moment of the pre-acquired useful signal, and judging whether a touch signal is generated or not by comparing the useful signal attenuation value with a preset useful signal attenuation threshold value, and specifically comprises the following steps: and when the useful signal attenuation value is larger than the preset useful signal attenuation threshold value, judging that a touch signal is generated.
2. The infrared touch screen signal conditioning circuit according to claim 1, wherein the charge-discharge circuit comprises a blocking capacitor and an analog switch, an output end of the photosensitive signal acquisition unit is electrically connected with an input end of the blocking capacitor, an output end of the blocking capacitor is electrically connected with an input end of the MCU, the analog switch is electrically connected with a connection node between the blocking capacitor and the MCU, the other end of the analog switch is grounded, and a control end of the analog switch is electrically connected with an output end of the MCU.
3. The infrared touch screen signal conditioning circuit according to claim 2, wherein an amplifier and an a/D converter are further arranged between the blocking capacitor and the MCU, an output end of the blocking capacitor is electrically connected with an input end of the amplifier, an output end of the amplifier is electrically connected with an input end of the a/D converter, and an output end of the a/D converter is electrically connected with an input end of the MCU.
4. The infrared touch screen signal conditioning circuit of claim 1, further comprising an acquisition module for acquiring a signal period of the useful signal, thereby acquiring a start time of the useful signal and a peak time of the useful signal.
5. The infrared touch screen signal conditioning circuit of claim 4, wherein the acquisition module employs an oscilloscope.
6. The signal conditioning method for the infrared touch screen is characterized by comprising the following steps of:
step one: receiving useful signals generated by the infrared touch screen;
step two: charging at the initial moment of the pre-obtained useful signal and performing grounding discharge at the peak moment of the pre-obtained useful signal, so as to discharge all pre-collected signals, wherein all the signals comprise useful signals and interference signals, and the interference signals comprise externally generated low-frequency signals and interference signals with the same frequency as the useful signals;
the second step further comprises the following steps: acquiring a useful signal attenuation value at a peak time of the useful signal obtained in advance, and judging whether a touch signal is generated or not by comparing the useful signal attenuation value with a preset useful signal attenuation threshold value, wherein the method specifically comprises the following steps: and when the useful signal attenuation value is larger than the preset useful signal attenuation threshold value, judging that a touch signal is generated.
7. The method for conditioning an infrared touch screen signal according to claim 6, further comprising, before the step one: and acquiring the signal period of the useful signal through an oscilloscope, thereby acquiring the starting time of the useful signal and the wave crest time of the useful signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010915438.8A CN112068737B (en) | 2020-09-03 | 2020-09-03 | Infrared touch screen signal conditioning circuit and method |
Applications Claiming Priority (1)
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