CN214704590U - Ambient light identification circuit for infrared touch screen - Google Patents
Ambient light identification circuit for infrared touch screen Download PDFInfo
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- CN214704590U CN214704590U CN202120361449.6U CN202120361449U CN214704590U CN 214704590 U CN214704590 U CN 214704590U CN 202120361449 U CN202120361449 U CN 202120361449U CN 214704590 U CN214704590 U CN 214704590U
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Abstract
The utility model discloses an ambient light identification circuit for infrared touch-sensitive screen, including signal sampling module, signal processing module, be arranged in discerning the light intensity identification module of illumination intensity among the alternating current signal and be arranged in the control module according to illumination intensity adjustment sampling cycle among the alternating current signal. The utility model discloses an ambient light identification circuit for infrared touch-sensitive screen, through the interference signal cycle among the light intensity identification module discernment alternating current signal and with predetermine the cycle and carry out the comparison, according to the interference signal cycle among the alternating current signal and the sampling cycle of predetermineeing the comparative result adjustment signal sampling module of cycle, thereby make the sampling cycle of signal sampling module change along with external illumination intensity's change, the sampling cycle of extension under the highlight environment, shorten the sampling cycle under indoor environment, can have indoor and outdoor light intensity environment simultaneously concurrently, wide application scope, high sampling efficiency.
Description
Technical Field
The utility model belongs to the technical field of the photoelectricity, concretely relates to ambient light identification circuit for infrared touch screen.
Background
At present, a receiving and amplifying circuit for an infrared touch screen photoelectric signal has various structures, for example, a high-speed amplifier with high price is directly adopted as an amplifying structure for sampling and holding, or an operational amplifier is adopted to construct an adder and then an input signal is subtracted to obtain a photoelectric signal. Among them, the most common way is: the photoelectric signal generates resistance value change on the infrared receiving circuit, then outputs a tiny alternating current signal, is isolated by the isolating capacitor, and then is output to the amplifier for signal amplification.
Along with the expansion of the application range of the infrared touch screen, the infrared touch screen needs to be capable of identifying indoor weak photoelectricity and also needs to have the characteristic of identifying outdoor strong light, when the outdoor strong light irradiates the receiving circuit, the output level of the receiving circuit is increased, the voltage difference generated by signals before and after switching is also increased, the voltage amplitude of a pulse bulge (namely an interference signal) generated by the voltage difference after the DC blocking capacitor is also increased, the discharge time is also prolonged, meanwhile, a rear-stage amplifier can cause saturation distortion after amplifying the interference signal, and the useful signal is interfered, so that the infrared touch screen generates the phenomena of false touch, common origin, wire jumping and the like.
The existing processing method is to prolong the time interval from the opening of the channel of the infrared receiving tube to the normal sampling signal and avoid the interference signal, although the method enhances the light resistance of the infrared touch screen, the method also prolongs the signal sampling period of the infrared touch screen, and most of the using environments (such as indoor) do not need to provide time margin.
SUMMERY OF THE UTILITY MODEL
In order to solve the problem, the utility model provides an ambient light identification circuit for infrared touch-sensitive screen has indoor and outdoor light intensity environment concurrently simultaneously, and application scope is wide, and the sampling efficiency is high.
The utility model adopts the technical proposal that:
the utility model provides an environment light identification circuit for infrared touch-sensitive screen, is including the signal sampling module that is used for sampling photoelectric signal and changes into alternating current signal, be used for carrying out signal processing's signal processing module, the light intensity identification module that is arranged in discerning the alternating current signal illumination intensity and be arranged in according to the control module of alternating current signal illumination intensity adjustment sampling period, signal processing module is connected to signal sampling module electricity, signal processing module, light intensity identification module and signal sampling module are connected to the control module electricity, light intensity identification module electricity is connected at signal sampling module and signal processing module's common junction or signal processing module and control module's common junction.
Preferably, the signal processing module includes a current blocking unit for blocking an ac signal and a signal amplifying unit for amplifying the ac signal, the current blocking unit is electrically connected to the signal amplifying unit, and the light intensity identifying module is electrically connected to a common connection point of the signal sampling module and the current blocking unit, or a common connection point of the current blocking unit and the signal amplifying unit, or a common connection point of the signal amplifying unit and the control module.
Preferably, the signal sampling module is a receiving circuit including an infrared receiving tube.
Preferably, the current blocking unit is a capacitor.
Preferably, the signal amplification unit includes one or more signal amplifiers electrically connected in sequence.
Preferably, the light intensity identification module is a discrete component, a logic IC, a microprocessor or a programmable logic device.
Preferably, the light intensity identification device comprises a plurality of signal sampling modules and a plurality of signal processing modules, the number of the signal sampling modules is equal to that of the signal processing modules, each signal sampling module is electrically connected with each signal processing module and the control module in sequence, and the light intensity identification module is electrically connected with the common connection position of each signal sampling module and each signal processing module or the common connection position of each signal processing module and the control module.
Compared with the prior art, the utility model discloses an ambient light identification circuit for infrared touch-sensitive screen, be changed into alternating current signal and export to signal processing module and light intensity identification module behind the sampling photoelectric signal through signal sampling module, through the interference signal cycle among the light intensity identification module discernment alternating current signal and with predetermine the cycle and compare, according to the interference signal cycle among the alternating current signal and the sampling cycle of predetermineeing periodic comparison result adjustment signal sampling module, thereby make signal sampling module's sampling cycle change along with external illumination intensity's change, the sampling cycle of extension under the highlight environment, shorten sampling cycle under indoor environment, can have indoor and outdoor light intensity environment simultaneously concurrently, application scope is wide, sampling efficiency is high.
Drawings
Fig. 1 is a circuit diagram of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 2 is a single-channel circuit diagram of an ambient light recognition circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 3 is a first multi-channel circuit diagram of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 4 is a second multi-channel circuit diagram of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 5 is a third multi-channel circuit diagram of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 6 is a signal waveform diagram of a third multi-channel circuit of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 7 is a fourth multi-channel circuit diagram of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 8 is a signal waveform diagram of a fourth multi-channel circuit of an ambient light identification circuit for an infrared touch screen according to embodiment 1 of the present invention;
fig. 9 is a flowchart of a control method of an ambient light identification circuit for an infrared touch screen according to embodiment 2 of the present invention.
Description of the reference numerals
The device comprises a signal sampling module, a signal processing module, a current blocking unit, a signal amplifying unit, a light intensity identification module and a control module, wherein the signal sampling module is 1, the signal processing module is 2, the current blocking unit is 21, the signal amplifying unit is 22, and the control module is 4.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
The embodiment 1 of the utility model provides an ambient light recognition circuit for infrared touch screen, as shown in fig. 1-8, including signal sampling module 1 that is used for sampling photoelectric signal and changes into alternating current signal, be used for carrying out signal processing's signal processing module 2, the light intensity identification module 3 that is arranged in discerning the alternating current signal illumination intensity and be arranged in the control module 4 according to the illumination intensity adjustment sampling period in the alternating current signal, signal processing module 2 is connected to signal sampling module 1 electricity, signal processing module 2, light intensity identification module 3 and signal sampling module 1 are connected to control module 4 electricity, 3 electricity of light intensity identification module are connected in signal sampling module 1 and signal processing module 2's common junction or signal processing module 2 and control module 4's common junction.
Thus, the photoelectric signal is sampled by the signal sampling module 1 and then converted into an alternating current signal, the alternating current signal is output to the signal processing module 2 and the light intensity identification module 3, the period of the interference signal in the alternating current signal is identified by the light intensity identification module 3 and compared with the preset period, and the sampling period of the signal sampling module 1 is adjusted according to the comparison result of the period of the interference signal in the alternating current signal and the preset period, namely, if the period of the interference signal in the alternating current signal is smaller than the preset period, the sampling period of the signal sampling module 1 is shortened; if interference signal cycle among the alternating current signal is greater than preset cycle, then increases signal sampling module 1's sampling cycle to make signal sampling module 1's sampling cycle change along with external illumination intensity's change, the sampling cycle of extension under the highlight environment shortens sampling cycle under indoor environment, can have indoor and outdoor light intensity environment simultaneously concurrently, application scope is wide, and sampling efficiency is high.
The signal processing module 2 comprises a current blocking unit 21 for blocking an alternating current signal and a signal amplifying unit 22 for amplifying the alternating current signal, the current blocking unit 21 is electrically connected with the signal amplifying unit 22, and the light intensity identification module 3 is electrically connected to a common connection position of the signal sampling module 1 and the current blocking unit 21, or a common connection position of the current blocking unit 21 and the signal amplifying unit 22, or a common connection position of the signal amplifying unit 22 and the control module 4.
In this way, the ac signal is subjected to the dc blocking process by the current blocking means 21, and the ac signal is amplified by the signal amplifying means 22, so that a weak infrared photoelectric signal is processed into an amplified ac signal.
The signal sampling module 1 is a receiving circuit comprising an infrared receiving tube.
In this way, the signal sampling module 1 is a receiving circuit including an infrared receiving tube, so as to sample an infrared photoelectric signal in an indoor or outdoor environment.
The current blocking unit 21 is a capacitor.
In this way, the current blocking unit 21 is a capacitor, and blocks the dc signal of the infrared photoelectric signal and allows only the ac signal of the infrared photoelectric signal to pass therethrough.
The signal amplification unit 22 includes one or more signal amplifiers electrically connected in sequence.
In this way, the signal amplification unit 22 includes one or more signal amplifiers electrically connected in sequence, so that the weak ac signal processed by the current blocking unit 21 is subjected to one-stage or multi-stage amplification processing.
The light intensity identification module 3 is a discrete component, a logic IC, a microprocessor or a programmable logic device.
Thus, the light intensity identification module 3 is a discrete component, a logic IC, a microprocessor or a programmable logic device, and the embodiment adopts an or gate as the light intensity identification module 3 (i.e., an ambient light identification circuit), so as to identify the period of the interference signal in the alternating current signal and compare the period with the preset period, and if the period of the interference signal in the alternating current signal is smaller than the preset period, the sampling period of the signal sampling module is shortened; and if the period of the interference signal in the alternating current signal is greater than the preset period, increasing the sampling period of the signal sampling module.
Including a plurality of signal sampling module 1 and a plurality of signal processing module 2, the quantity of signal sampling module 1 equals with the quantity of signal processing module 2, every signal sampling module 1 electricity connection in proper order is every signal processing module 2 and control module 4, light intensity identification module 3 electricity is connected in the common junction department of every signal sampling module 1 and every signal processing module 2 or the common junction department of every signal processing module 2 and control module 4.
Therefore, a plurality of sampling channels are formed by the plurality of signal sampling modules 1 and the plurality of signal processing modules 2 to sample infrared photoelectric signals, and alternating current signals are input to the light intensity identification module 3 after the light intensity identification module 3 is electrically connected through a plurality of sampling channels, so that the light intensity identification module 3 can realize multi-channel input and single-channel output, the number of I/O ports of the control module 4(MCU) is reduced, and the working efficiency is improved; the multiple sampling channels can also be electrically connected with a plurality of I/O ports of a control module 4(MCU) of the infrared touch screen, so that the function of recognizing strong light interference of the infrared touch screen under the condition of external light is realized.
Interference mode of interference source: when external illumination is in a certain intensity, the signal sampling module 1 (i.e. the receiving circuit) generates an interference signal g (x) with a voltage value for a certain time during switching, the time of the interference signal g (x) is increased along with the rise of the illumination intensity, the direct-current voltage of a useful signal is too high after the useful signal is superposed by the interference signal g (x), and saturation distortion is caused after the useful signal is amplified by an amplifier.
As shown in fig. 2, an or gate input terminal (which may also be sampled at the output terminal of the receiving circuit and the input terminal of the primary amplifier according to the implementation method) is connected in parallel to a connection channel from the output terminal of the primary amplifier to the input terminal of the secondary amplifier of the photoelectric signal amplification channel, the other end of the or gate is connected to ground, and the output terminal of the or gate is connected to an MCU that controls the operation of the infrared touch screen. JL1 and JL2 in the figure are cross-coupling elements.
Because the utility model discloses what utilize is the pulse bulge signal g (x) that produces at blocking electric capacity both ends among the receiving circuit, pulse bulge signal g (x) has two kinds of expression forms in photoelectric signal amplifier circuit: one is the distortion of the clipping generated after passing through the amplifier as shown in fig. 6, and the other is the waveform of the signal sampled at the output terminal of the receiving circuit as shown in fig. 8.
The working principle of identifying strong light interference is as follows:
as shown in fig. 5-6, the interference signal g (x) has a relatively large level, which is much larger than the useful signal level, the or gate (i.e. the light intensity identification module 3) collects the output signal of the receiving circuit (i.e. the signal sampling module 1) as a judgment basis, when the external illumination intensity increases to irradiate the infrared touch screen, the time (T2-T1) of the interference signal g (x) in the receiving circuit gradually increases to (T6-T5), or the time of the high pulse width of the signal output to the control module 4(MCU) after gate sampling increases from (T4-T3) to (T8-T7), the control module 4(MCU) identifies the input high pulse signal width (T8-T7) > (T4-T3), adjusts the sampling time interval from (T1-T0) to (T3-T2), and makes the interference signal g (x) cause a high voltage region, ensuring that the useful signal is not interfered; when the MCU for controlling the infrared touch screen to work detects that the time of the ambient light recognition circuit outputting square waves is reduced, the MCU controls the time of switching the receiving circuit, reduces the interval time of avoiding interference signals g (x), improves the scanning speed of the infrared touch screen, and improves the response time and the writing effect of the infrared touch screen. The embodiment is influenced by the parameters of the infrared receiving tube, and before the infrared receiving tube is not interfered by external strong light, the level of a part of interference signals (namely pulse convex signals) g (x) is not enough to reach the conducting voltage of an OR gate, but the infrared receiving tube is sensitive to the change of the strong ambient light.
As shown in fig. 7-8, the level of the interference signal pulse protrusion signal g (x) is relatively large, the primary amplifier outputs a signal whose top is clipped to form a square wave, the amplitude of the square wave signal is stable, the or gate (i.e. the light intensity identification module 3) collects the output signal of the amplifier as a judgment basis, when the external illumination intensity increases and irradiates the infrared touch screen, the receiving circuit (i.e. the signal sampling module 1) switches to generate the interference signal g (x), the interference signal g (x) is saturated and distorted after the amplification of the amplifier, the time (t2-t1) of the interference signal g (x) is gradually increased to (t6-t5), or the time (t2-t1) of the signal high pulse width output to the control module 4(MCU) after the gate sampling is increased from (t4-t3) to (t8-t7), the control module 4(MCU) identifies that the input high pulse width (t8-t7) is > (t4-t3), the sampling time interval is adjusted to be increased from (T1-T0) to (T3-T2), a high voltage area caused by interference signal pulse bump signals is made available, and a useful signal is guaranteed not to be interfered; when the MCU for controlling the infrared touch screen to work detects that the time of the ambient light recognition circuit outputting square waves is reduced, the MCU controls the time of switching the receiving circuit, reduces the interval time of avoiding interference signals g (x), improves the scanning speed of the infrared touch screen, and improves the response time and the writing effect of the infrared touch screen.
The receiving circuit (namely the signal sampling module 1) can generate an interference signal g (x) with a certain voltage value when switching, the voltage value of the interference signal g (x) is far higher than that of a useful signal, the logic circuit (namely the light intensity identification module 3) can be used for judging the high and low level of the voltage value of the interference signal g (x), and the interference signal g (x) is identified as a high-level pulse by the logic circuit and is provided for the control module 4(MCU) to identify the external strong light interference.
The processing mode of the infrared touch screen in the strong light environment is as follows: the microprocessor (i.e., the control module 4) recognizes the output signal of the or gate and adjusts the timing of the useful signal to avoid the interference signal g (x). When the time of the high-level signal received by the MCU (namely the control module 4) is less than a set threshold value, the infrared touch screen microprocessor judges that the switching time of the infrared receiving circuit (namely the signal sampling module 1) can be shortened, and the system controls to quicken the acquisition of the infrared touch useful signal; when the time of the high-level signal received by the MCU (namely the control module 4) exceeds a set threshold value, the infrared touch system judges that the switching time of the infrared receiving circuit needs to be lengthened, and increases the time g (x) for avoiding the external light interference after the receiving circuit (namely the signal sampling module 1) is opened, so that the useful analog signal is not influenced by the external light interference signal g (x), the useful analog signal is normally amplified by the amplifier, and the MCU (namely the control module 4) acquires an accurate AD signal.
Because the transmitting and receiving driving circuits of the infrared touch screen are all in a matrix structure, the number of the used OR gates can be adjusted according to the required sensitivity according to the number of the used channels of the receiving circuit (namely, the signal sampling module 1), and the greater the number of the used OR gates, the more sensitive the light identification resistance is.
The utility model discloses utilize light intensity identification module 3 to handle interference signal g (x) that is produced by external illumination intensity, provide MCU a signal that increases high impulse time along with external illumination intensity reinforcing, MCU can judge through this signal that infrared touch system is in external highlight environmental interference and environmental light intensity change, and can dodge external highlight through controlling infrared receiving tube timing (sampling period) and produce interference signal g (x), make the response time that promotes infrared touch-sensitive screen through faster scanning speed under normal environment, dodge interference signal g (x) through increasing light intensity identification module 3 switching time under the highlight environment and make infrared touch-sensitive screen not receive the interference and normally work, kill two birds with one stone.
The utility model discloses an environment light identification circuit for infrared touch-sensitive screen, be changed into alternating current signal and export to signal processing module and light intensity identification module behind the sampling photoelectric signal through signal sampling module, through the interference signal cycle among the light intensity identification module discernment alternating current signal and compare with the cycle of predetermineeing, adjust signal sampling module's sampling cycle according to the interference signal cycle among the alternating current signal and the comparative result of predetermineeing the cycle, thereby make signal sampling module's sampling cycle change along with external illumination intensity's change, the sampling cycle of extension under the highlight environment, shorten sampling cycle under indoor environment, can have indoor and outdoor light intensity environment simultaneously concurrently, application scope is wide, the sampling efficiency is high.
Example 2
As shown in fig. 9, embodiment 2 of the present invention provides a control method for an ambient light identification circuit of an infrared touch screen, which specifically includes the following steps:
s1, sampling the photoelectric signal by the signal sampling module, converting the photoelectric signal into an alternating current signal and outputting the alternating current signal to the signal processing module and the light intensity identification module;
s2, processing the alternating current signal through the signal processing module and outputting the processed alternating current signal to the control module, and acquiring a useful signal from the processed alternating current signal through the control module;
and identifying the period of the interference signal in the alternating current signal through the light intensity identification module, comparing the period with a preset period, and adjusting the sampling period of the signal sampling module according to the comparison result of the period of the interference signal in the alternating current signal and the preset period.
Therefore, the photoelectric signal is sampled by the signal sampling module and then converted into an alternating current signal, and the alternating current signal is output to the signal processing module and the light intensity identification module; the current blocking unit is used for blocking the alternating current signals and then sending the alternating current signals to the signal amplification unit, the signal amplification unit is used for amplifying the alternating current signals and then sending the alternating current signals to the control module, and the control module is used for acquiring useful signals from the alternating current signals subjected to signal processing so as to normally receive input signals of the infrared touch screen;
and identifying the period of the interference signal in the alternating current signal through the light intensity identification module and comparing the period with a preset period, if the period of the interference signal in the alternating current signal is less than the preset period, reducing the sampling period of the signal sampling module, otherwise, increasing the sampling period of the signal sampling module.
The utility model discloses a control method, be changed into alternating current signal and export to signal processing module and light intensity identification module after sampling photoelectric signal through signal sampling module, through the interference signal cycle among the light intensity identification module discernment alternating current signal and compare with preset cycle, adjust signal sampling module's sampling cycle according to the interference signal cycle among the alternating current signal and preset cycle's comparative result, thereby make signal sampling module's sampling cycle change along with external illumination intensity's change, the sampling cycle of extension under the highlight environment, shorten sampling cycle under indoor environment, can have indoor and outdoor light intensity environment simultaneously concurrently, application scope is wide, the sampling efficiency is high.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention should be covered by the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (7)
1. An ambient light identification circuit for an infrared touch screen is characterized by comprising a signal sampling module (1) for sampling a photoelectric signal and converting the photoelectric signal into an alternating current signal, a signal processing module (2) for processing the alternating current signal, a light intensity identification module (3) for identifying the illumination intensity in the alternating current signal and a control module (4) for adjusting the sampling period according to the illumination intensity in the alternating current signal, the signal sampling module (1) is electrically connected with the signal processing module (2), the control module (4) is electrically connected with the signal processing module (2), the light intensity identification module (3) and the signal sampling module (1), the light intensity identification module (3) is electrically connected with the common connection position of the signal sampling module (1) and the signal processing module (2) or the common connection position of the signal processing module (2) and the control module (4).
2. The ambient light recognition circuit for the infrared touch screen is characterized in that the signal processing module (2) comprises a current blocking unit (21) for blocking an alternating current signal and a signal amplifying unit (22) for amplifying the alternating current signal, the current blocking unit (21) is electrically connected with the signal amplifying unit (22), and the light intensity recognition module (3) is electrically connected with a common connection position of the signal sampling module (1) and the current blocking unit (21), or a common connection position of the current blocking unit (21) and the signal amplifying unit (22), or a common connection position of the signal amplifying unit (22) and the control module (4).
3. The ambient light recognition circuit for infrared touch screens according to claim 2, characterized in that the signal sampling module (1) is a receiving circuit comprising an infrared receiving tube.
4. The ambient light recognition circuit for an infrared touch screen according to claim 3, characterized in that the current blocking unit (21) is a capacitor.
5. The ambient light recognition circuit for an infrared touch screen according to claim 4, characterized in that the signal amplification unit (22) comprises one or more signal amplifiers electrically connected in sequence.
6. The ambient light recognition circuit for infrared touch screens according to claim 5, characterized in that the light intensity recognition module (3) is a discrete component, a logic IC, a microprocessor or a programmable logic device.
7. The ambient light identification circuit for the infrared touch screen according to any one of claims 1 to 6, comprising a plurality of signal sampling modules (1) and a plurality of signal processing modules (2), wherein the number of the signal sampling modules (1) is equal to the number of the signal processing modules (2), each signal sampling module (1) is electrically connected with each signal processing module (2) and the control module (4) in turn, and the light intensity identification module (3) is electrically connected at the common connection position of each signal sampling module (1) and each signal processing module (2) or the common connection position of each signal processing module (2) and the control module (4).
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114623851A (en) * | 2022-03-08 | 2022-06-14 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
| CN114911366A (en) * | 2021-02-09 | 2022-08-16 | 安徽富创通科技有限公司 | Ambient light identification circuit for infrared touch screen and control method thereof |
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2021
- 2021-02-09 CN CN202120361449.6U patent/CN214704590U/en active Active
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114911366A (en) * | 2021-02-09 | 2022-08-16 | 安徽富创通科技有限公司 | Ambient light identification circuit for infrared touch screen and control method thereof |
| CN114623851A (en) * | 2022-03-08 | 2022-06-14 | 欧姆龙(上海)有限公司 | Photoelectric sensor and control method thereof |
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