CN112068737A - Infrared touch screen signal conditioning circuit and method - Google Patents
Infrared touch screen signal conditioning circuit and method Download PDFInfo
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Abstract
The application discloses infrared touch screen signal conditioning circuit and method, through receiving the useful signal after, control charge-discharge circuit is in acquireing in advance the useful signal's inception moment charges, still is used for controlling charge-discharge circuit is in acquireing in advance the crest of useful signal carries out ground discharge constantly to directly discharge the outside all signals that produce of gathering in advance, and then avoid the useful signal and the influence that the signal attenuation that interference signal stack produced brought, solve the problem that interference signal of low frequency interference signal and same or similar frequency disturbs to the normal discernment of touch action of infrared touch screen and carry out the interference, can satisfy many infrared touch screens and use side by side to can adapt to the environment that has the interference source, improved the interference killing feature.
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 infrared transmitting tube and photosensitive tube, and through infrared transmitting tube to photosensitive tube transmission infrared ray, thereby constitute infrared ray, and a plurality of infrared transmitting tubes are to a plurality of photosensitive tube transmission infrared ray, then form intensive infrared ray light net on whole touch screen surface, and simultaneously, the photosensitive tube receives behind the infrared ray and converts photoelectric conversion into the signal of telecommunication into, finally convert into digital signal through AD through signal amplification and be discerned by MCU, and when opaque object sheltered from the infrared ray on the touch screen surface, then MCU can discern and shelter from the object, and simultaneously, MCU calculates the coordinate output of touch object according to the relative position of disappearance light, thereby accomplish the touch control action.
At present, the practical problem of the infrared touch screen is that when two infrared touch screens are placed side by side and the relative angle is less than 180 degrees, then the signals of the two infrared touch screens interfere with each other, if the light of the transmitting tube of one infrared touch screen irradiates on the photosensitive tube of the other infrared touch screen, the signal identification of the MCU is disordered, and the touch control action cannot be completed correctly, or when the frequency is close to the interference source of the working frequency of the infrared touch screen, the normal work of the infrared touch screen can be influenced, and the MCU cannot identify the touch action correctly.
The two practical problems are interference belonging to the same frequency or similar frequency, and are represented as a waveform timing diagram under a normal working signal of the infrared touch screen as shown in fig. 2, and due to the charge and discharge of a capacitor in a circuit, a signal of the infrared touch screen is in a sine wave form in each signal period and has wave crests and wave troughs; when the interference source with the same frequency is close to the infrared touch screen, a signal waveform time sequence shown in fig. 3 appears in the first case, which is represented as working signals with the same frequency and time domain with even number of half cycles of difference, namely, the wave crests are mutually superposed, and the wave troughs are mutually superposed, so that the working signals are enhanced; in the second case, a signal waveform timing sequence as shown in fig. 4 appears, which represents working signals with the same frequency and time domain different by an odd number of half cycles, i.e. the peaks and the troughs are superimposed, so that the working signals cancel each other. The two interference conditions can affect the normal work of the infrared touch screen, the MCU cannot correctly recognize the touch action, in practical application, an interference source with similar frequency is close to the infrared touch screen, the signal time sequence of the interference source is between the normal working signal of the infrared touch screen and the working signal with the same frequency and time domain with the difference of odd number of half cycles, and the MCU can also be affected to correctly recognize the touch action.
To above-mentioned interference problem, current circuit can't be solved, only can change infrared touch screen structure to the realization shelters from interference signal, if contract in the photosensitive tube within the structure, or when infrared touch screen side by side was put, its relative angle was greater than 180, etc.. However, the above changes to the structure may make the structure inflexible, resulting in a poor user experience.
Chinese patent publication No. CN101893968 discloses a signal processing circuit for an infrared touch screen, which includes a signal receiving circuit, a microcontroller and a high-pass filter circuit, where the high-pass filter circuit includes a capacitor and a grounded analog switch, and the microcontroller can control the analog switch to be closed to filter an ambient light signal, but it can be understood that the frequency of the ambient light signal is lower than that of the infrared touch screen, and this method removes a low-frequency interference signal through the high-pass filter circuit, but for an interference signal having the same or similar frequency to that of the infrared touch screen, the interference signal cannot be filtered, which affects the MCU to correctly recognize a touch action and correctly recognize a 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 existing low-frequency interference signal and the interference signal with the same or similar frequency interfere the normal recognition of the touch action of the infrared touch screen.
In view of this, the first aspect of the present application provides a signal conditioning circuit for an infrared touch screen, where the infrared touch screen includes an infrared emission tube, including: the photosensitive signal acquisition unit, the charge and discharge circuit and the MCU are connected;
the input end of the charge and discharge circuit is electrically connected with the output end of the photosensitive signal acquisition unit, the first output end of the charge and discharge circuit is electrically connected with the input end of the MCU, and the second output end of the charge and 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 and discharge circuit;
the MCU is used for controlling the charging and discharging circuit to charge at the initial moment of the useful signal obtained in advance after receiving the useful signal collected by the photosensitive signal collecting unit, and is also used for controlling the charging and discharging circuit to perform grounding discharge at the peak moment of the useful signal obtained in advance, so that all signals collected by the photosensitive signal collecting unit in advance are discharged.
Preferably, the MCU is further configured to acquire a useful signal attenuation value at a peak time of the useful signal obtained in advance, and determine whether to generate a touch signal by comparing the useful signal attenuation value with a preset useful signal attenuation threshold, specifically including: 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 and 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 connection 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 disposed between the blocking capacitor and the MCU, an output end of the blocking capacitor is electrically connected to an input end of the amplifier, an output end of the amplifier is electrically connected to an input end of the a/D converter, and an output end of the a/D converter is electrically connected to an input end of the MCU.
Preferably, the infrared touch screen signal conditioning circuit further comprises an obtaining module, configured to obtain a signal cycle of the useful signal, so as to obtain a start time of the useful signal and a peak time of the useful signal.
Preferably, the acquisition module adopts an oscilloscope.
On the other hand, the embodiment of the application also provides a signal conditioning method for the infrared touch screen, which comprises the following steps:
the method comprises the following steps: receiving a useful signal generated by an infrared touch screen;
step two: all signals collected in advance are discharged by charging at the starting moment of the useful signal obtained in advance and performing grounding discharge at the peak moment of the useful signal obtained in advance.
Preferably, the step two further comprises: acquiring a useful signal attenuation value at a peak moment of the useful signal acquired in advance, and comparing the useful signal attenuation value with a preset useful signal attenuation threshold value to judge whether a touch signal is generated, 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 is preceded by: and acquiring the signal period of the useful signal through an oscilloscope, thereby acquiring the starting time of the useful signal and the peak time of the useful signal.
According to the technical scheme, the embodiment of the application has the following advantages:
the embodiment of the application provides a pair of infrared touch screen signal conditioning circuit, after receiving useful signal, control charge-discharge circuit is in acquireing in advance useful signal's inception moment charges, still is used for controlling charge-discharge circuit is in acquireing in advance useful signal's crest carries out ground discharge constantly to directly discharge the outside all signals that produce of gathering in advance, and then avoid interference signal and the influence that the signal attenuation that useful signal superposes and produce brought, solve the interference signal of low frequency interference signal and same or similar frequency and normally discern the problem of disturbing to infrared touch screen's touch action, can satisfy many infrared touch screen and use side by side to can adapt to there being the environment of interference source, improved the interference killing feature. The signal conditioning method for the infrared touch screen provided by the embodiment of the application has the same beneficial effects as the embodiment.
Drawings
FIG. 1 is a schematic structural diagram of an infrared touch screen in the prior art;
FIG. 2 is a timing diagram illustrating waveforms of normal operating signals of an infrared touch screen in the prior art;
FIG. 3 is a waveform timing diagram of signals of an infrared touch screen and an interference signal which are different in time domain with the same frequency by even half cycles in the prior art;
FIG. 4 is a waveform timing diagram of signals with the same frequency and time domain difference of odd number of half cycles between the infrared touch screen and the interference signal in the prior art;
fig. 5 is a schematic structural diagram of an infrared touch screen signal conditioning circuit according to an embodiment of the present disclosure;
FIG. 6 is a timing diagram illustrating waveforms of useful signals in a signal conditioning circuit of an infrared touch screen according to an embodiment of the present disclosure;
fig. 7 is another schematic structural diagram of an infrared touch screen signal conditioning circuit according to an embodiment of the present disclosure;
fig. 8 is a flowchart of a signal conditioning method for an infrared touch screen according to an embodiment of the present disclosure;
fig. 9 is another flowchart of a method for conditioning signals of an infrared touch screen according to an embodiment of the present disclosure.
Detailed Description
In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
For easy understanding, please refer to fig. 5, in this embodiment, a signal conditioning circuit for an infrared touch screen is provided, where the infrared touch screen includes an infrared transmitting tube, and includes: the device comprises a photosensitive signal acquisition unit 1, a charge and discharge circuit 2 and an MCU 3;
the input end of the charge and discharge circuit 2 is electrically connected with the output end of the photosensitive signal acquisition unit 1, the first output end of the charge and discharge circuit 2 is electrically connected with the input end of the MCU3, and the second output end of the charge and discharge circuit 2 is grounded;
the photosensitive signal acquisition unit 1 is used for acquiring useful signals generated by the infrared transmitting tube and transmitting the useful signals to the MCU3 through the charge and discharge circuit 2;
it should be noted that the photosensitive signal acquisition unit 1 preferably adopts 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 configured to control the charging and discharging circuit 2 to charge at the starting time of the pre-obtained useful signal after receiving the useful signal collected by the photosensitive signal collecting unit 1, and also to control the charging and discharging circuit 2 to perform ground discharge at the peak time of the pre-obtained useful signal, so as to discharge all signals collected by the photosensitive signal collecting unit 1 in advance.
It is understood that all signals include the useful signal and the interference signal, and in this embodiment, the interference signal includes the externally generated low frequency signal and the interference signal having the same or similar frequency as the useful 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 is generated according to a signal attenuation value generated by the useful signal. When the external part of the device is interfered by infrared signals or other light source signals, the interference 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 are possible to enter at any time of the signal period of the useful signals, and the subsequent processing condition of the useful signals is influenced. In particular, interference signals having the same frequency as the useful signal can influence the processing of the useful signal.
In the present embodiment, as shown in fig. 6, a waveform timing chart of useful signals is shown, wherein in a signal period of a first useful signal, at a time t0, a power supply is turned on, a charging and discharging circuit starts to be charged, and until a time t1 is a peak time, the charging and discharging circuit is controlled to be grounded (0V) to be discharged, so that an interference signal starts to be discharged at a time t 1; and when the starting time t0 'of the signal period of the second useful signal, charging is started, and when the peak time t 1' is, grounding discharge is started, namely, charging is quickly performed after the peak value is reached, and so on, charging and discharging are performed in a circulating mode in the signal period of each useful signal, so that all signals collected at any time can be discharged, the interference signal and the useful signal do not generate the peak and the trough, the influence caused by signal attenuation generated by superposition of the interference signal and the useful signal is avoided, and the interference signal and the useful signal are superposed, such as peak superposition, trough superposition or peak and trough superposition of two signals and the like.
In addition, when the infrared touch screen is not shielded or touched, signal attenuation cannot be generated, and judgment of no touch cannot be influenced naturally.
When the infrared touch screen is shielded or touched, the touch signal can bring about signal attenuation of a larger amplitude, although the interference signal generates a superposed signal to a useful signal, a certain signal value can be promoted, when the interference signal is caused by an external interference source, compared with the touch signal, the signal attenuation condition is still present on the overall signal value, and the overall signal attenuation value can be judged as the touch signal as long as the signal attenuation value is greater than a preset attenuation threshold value, so that the interference signal does not influence the judgment of the MCU on the touch signal, the problem of the interference source with similar frequency is solved, the condition that a plurality of infrared touch screens are used side by side can be met, the environment with the interference source can be adapted, and the anti-interference capability is improved.
The above is an embodiment of an infrared touch screen signal conditioning circuit provided by the present application, and the following is another embodiment of an infrared touch screen signal conditioning circuit provided by the present application.
For convenience of understanding, please refer to fig. 7, in the present embodiment, a signal conditioning circuit for an infrared touch screen is provided, where the infrared touch screen includes an infrared transmitting tube, and includes: the device comprises a photosensitive signal acquisition unit 1, a charge and discharge circuit 2 and an MCU 3;
the input end of the charge and discharge circuit 2 is electrically connected with the output end of the photosensitive signal acquisition unit 1, the first output end of the charge and discharge circuit 2 is electrically connected with the input end of the MCU3, and the second output end of the charge and discharge circuit 2 is grounded;
the photosensitive signal acquisition unit 1 is used for acquiring useful signals generated by the infrared transmitting tube and transmitting the useful signals to the MCU3 through the charge and discharge circuit 2;
it should be noted that the photosensitive signal acquisition unit 1 preferably adopts 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 configured to control the charging and discharging circuit 2 to charge at the starting time of the pre-obtained useful signal after receiving the useful signal collected by the photosensitive signal collecting unit 1, and also to control the charging and discharging circuit 2 to perform ground discharge at the peak time of the pre-obtained useful signal, so as to discharge all signals collected by the photosensitive signal collecting unit 1 in advance.
Further, the MCU3 is further configured to acquire a useful signal attenuation value at a peak time of a useful signal obtained in advance, and determine whether to generate a touch signal by comparing the useful signal attenuation value with a preset useful signal attenuation threshold, which specifically includes: and when the useful signal attenuation value is larger than a preset useful signal attenuation threshold value, judging that a touch signal is generated.
It should be noted that the peak time of the useful signal is the highest value of the useful signal, and the touch signal is determined more accurately by obtaining the corresponding attenuation value of the useful signal.
Further, the charging and discharging circuit 2 includes a blocking capacitor 20 and an analog switch 21, an output end of the photosensitive signal acquisition unit 1 is electrically connected to an input end of the blocking capacitor 20, an output end of the blocking capacitor 20 is electrically connected to an input end of the MCU3, the analog switch 21 is electrically connected to a connection node between the blocking capacitor 20 and the MCU3, the other end of the analog switch 21 is grounded (0V), and a control end of the analog switch 21 is electrically connected to an output end of the MCU 3.
It should be noted that, the charging and discharging circuit 2 is formed by the blocking capacitor 20 and the analog switch 21, the structure is simple, the cost is low, and low-frequency interference signals can be filtered out by matching the blocking capacitor 20 and the analog switch 21, so that only the interference signals with the same or similar frequency as the useful signals are subjected to charging and discharging control in the subsequent charging and discharging control, and the touch identification is more accurate.
In the present 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 terminal of the dc blocking capacitor 20 is electrically connected to an input terminal of the amplifier 22, an output terminal of the amplifier 22 is electrically connected to an input terminal of the a/D converter 23, and an output terminal of the a/D converter 23 is electrically connected to an input terminal of the MCU 3.
The amplifier 22 and the a/D converter 23 transmit the useful signal from which the low-frequency interference signal is filtered, 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.
Furthermore, the infrared touch screen signal conditioning circuit further comprises an acquisition module for acquiring a signal cycle of the useful signal, so as to acquire a starting time of the useful signal and a peak time of the useful signal.
Further, the acquisition module adopts an oscilloscope.
The above is another embodiment of the infrared touch screen signal conditioning circuit provided by the present application, and the following is an embodiment of an infrared touch screen signal conditioning method provided by the present application.
For convenience of understanding, please refer to fig. 8, the method for conditioning signals of an infrared touch screen provided in this embodiment includes the following steps:
the method comprises the following steps: receiving a useful signal generated by an infrared touch screen;
step two: all signals collected in advance are discharged by charging at the starting moment of the useful signal obtained in advance and performing grounding discharge at the peak moment of the useful signal obtained in advance.
It should be noted that, the useful signal generated by the infrared touch screen is received, and whether the touch signal is generated can be determined according to the signal attenuation value generated by the useful signal. When the external part of the device is interfered by an infrared signal or other light source signals, the device can also be received, and the interference signals are randomly generated and are not controllable, so that the interference signals can enter at any time of the signal period of the useful signals, and the subsequent processing condition of the useful signals can be influenced. In particular, interference signals having the same frequency as the useful signal can influence the processing of the useful signal.
In the present embodiment, as shown in fig. 6, a waveform timing chart of useful signals is shown, wherein in a signal period of a first useful signal, at a time t0, a power supply is turned on, a charging and discharging circuit starts to be charged, and until a time t1 is a peak time, the charging and discharging circuit is controlled to be grounded (0V) to be discharged, so that an interference signal starts to be discharged at a time t 1; and when the starting time t0 'of the signal period of the second useful signal, charging is started, and when the peak time t 1' is, grounding discharge is started, namely, charging is quickly performed after the peak value is reached, and so on, charging and discharging are performed in a circulating mode in the signal period of each useful signal, so that all signals collected at any time can be discharged, the interference signal and the useful signal do not generate the peak and the trough, the influence caused by signal attenuation generated by superposition of the interference signal and the useful signal is avoided, and the interference signal and the useful signal are superposed, such as peak superposition, trough superposition or peak and trough superposition of two signals and the like.
In addition, when the infrared touch screen is not shielded or touched, signal attenuation cannot be generated, and judgment of no touch cannot be influenced naturally.
When the infrared touch screen is shielded or touched, the touch signal can bring about signal attenuation of a larger amplitude, although the interference signal generates a superposed signal to a useful signal, a certain signal value can be improved, when the interference signal is caused by an external interference source, the signal attenuation condition is still present 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 greater 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 source with similar frequency is solved, the condition that a plurality of infrared touch screens are used side by side can be met, the environment with the interference source can be adapted, and the anti-interference capability is improved.
Further, step one also includes before: 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 an embodiment of a method for conditioning a signal of an infrared touch screen provided by the present application, and the following is another embodiment of a method for conditioning a signal of an infrared touch screen provided by the present application.
For convenience of understanding, please refer to fig. 9, the method for conditioning signals of an infrared touch screen provided in this embodiment includes the following steps:
the method comprises the following steps: receiving a useful signal generated by an infrared touch screen;
step two: charging at the starting moment of a 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;
step three: acquiring a useful signal attenuation value at a peak moment of a useful signal obtained in advance, and comparing the useful signal attenuation value with a preset useful signal attenuation threshold value to judge whether a touch signal is generated, wherein the method specifically comprises the following steps: and when the useful signal attenuation value is larger than a preset useful signal attenuation threshold value, judging that a touch signal is generated.
Further, step one also includes before: 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.
It should be noted that, in an 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 is equal to V1+ V2, during the use, the touch occlusion is to occlude 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, a 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 generally the preset useful signal attenuation threshold is set to 70%, that is, the signal attenuation value exceeds 70%, which may determine that the touch signal is generated, and in addition, the interference signal is an external interference source, and is much weaker than the touch signal, so the determination of the touch signal is not affected.
In the several embodiments provided in the present application, it should be understood that the disclosed apparatus and method may be implemented in other ways. For example, the above-described apparatus embodiments are merely illustrative, and for example, the division of the units is only one logical division, and other divisions may be realized in practice, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed 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 can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit. The integrated unit can be realized in a form of hardware, and can also be realized in a form of a software functional unit.
The integrated unit, if implemented in the form of a software functional unit and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application may be substantially implemented or contributed to by the prior art, or all or part of the technical solution may be embodied in a software product, which is stored in a storage medium and includes instructions for executing all or part of the steps of the method described in the embodiments of the present application through a computer device (which may be a personal computer, a server, or a network device). And the aforementioned storage medium includes: a U disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk or an optical disk, and other various media capable of storing program codes.
The above embodiments are only used for illustrating the technical solutions 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 solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.
Claims (9)
1. The utility model provides an infrared touch-sensitive screen signal conditioning circuit, infrared touch-sensitive screen includes infrared transmitting tube, its characterized in that includes: the photosensitive signal acquisition unit, the charge and discharge circuit and the MCU are connected;
the input end of the charge and discharge circuit is electrically connected with the output end of the photosensitive signal acquisition unit, the first output end of the charge and discharge circuit is electrically connected with the input end of the MCU, and the second output end of the charge and 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 and discharge circuit;
the MCU is used for controlling the charging and discharging circuit to charge at the initial moment of the useful signal obtained in advance after receiving the useful signal collected by the photosensitive signal collecting unit, and is also used for controlling the charging and discharging circuit to perform grounding discharge at the peak moment of the useful signal obtained in advance, so that all signals collected by the photosensitive signal collecting unit in advance are discharged.
2. The infrared touch screen signal conditioning circuit of claim 1, wherein the MCU is further configured to obtain a useful signal attenuation value at a peak time of the useful signal obtained in advance, and further configured to determine whether a touch signal is generated by comparing the useful signal attenuation value with a preset useful signal attenuation threshold, specifically comprising: and when the useful signal attenuation value is larger than the preset useful signal attenuation threshold value, judging that a touch signal is generated.
3. The infrared touch screen signal conditioning circuit of claim 1, wherein the charge and 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 connection 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.
4. The infrared touch screen signal conditioning circuit of claim 3, wherein an amplifier and an A/D converter are further disposed between the blocking capacitor and the MCU, an output end of the blocking capacitor is electrically connected to an input end of the amplifier, an output end of the amplifier is electrically connected to an input end of the A/D converter, and an output end of the A/D converter is electrically connected to an input end of the MCU.
5. The infrared touch screen signal conditioning circuit of claim 1 or 2, further comprising an acquisition module configured to acquire a signal period of the useful signal, thereby acquiring a start time of the useful signal and a peak time of the useful signal.
6. The infrared touch screen signal conditioning circuit of claim 5, wherein the acquisition module employs an oscilloscope.
7. A signal conditioning method for an infrared touch screen is characterized by comprising the following steps:
the method comprises the following steps: receiving a useful signal generated by an infrared touch screen;
step two: all signals collected in advance are discharged by charging at the starting moment of the useful signal obtained in advance and performing grounding discharge at the peak moment of the useful signal obtained in advance.
8. The method for conditioning signals of an infrared touch screen according to claim 7, further comprising, after the second step: acquiring a useful signal attenuation value at a peak moment of the useful signal acquired in advance, and comparing the useful signal attenuation value with a preset useful signal attenuation threshold value to judge whether a touch signal is generated, 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.
9. The method for conditioning signals of an infrared touch screen according to claim 7 or 8, wherein the first step is preceded by the further step of: and acquiring the signal period of the useful signal through an oscilloscope, thereby acquiring the starting time of the useful signal and the peak time of the useful signal.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202010915438.8A CN112068737B (en) | 2020-09-03 | 2020-09-03 | Infrared touch screen signal conditioning circuit and method |
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| CN202010915438.8A CN112068737B (en) | 2020-09-03 | 2020-09-03 | Infrared touch screen signal conditioning circuit and method |
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