An infrared detection circuit capable of preventing interference from external light sources

Abstract

The application discloses an infrared detection circuit capable of preventing interference of external light sources, comprising an infrared emission module, an infrared receiving module, an anti-interference module and a signal processing module. When a pulse control signal is received by the control end of the infrared emission module, the infrared emission module emits infrared light. When the infrared receiving module receives infrared light, the infrared receiving module converts the infrared light into a corresponding voltage signal. The anti-interference module is used for isolating the direct current interference signal generated by the external light source. The signal processing module is used for amplifying the voltage signal and transmitting the voltage signal to a controller to determine whether the voltage signal is the infrared light emitted by the infrared emission module. The anti-interference module is used for isolating the direct current interference signal generated by the external light source, so that the infrared sensor is prevented from being interfered by sunlight or strong light and the like external light sources, and malfunctions or abnormal work of the infrared sensor are avoided. In addition, after the direct current interference signal is isolated, the voltage signal is amplified, so that the voltage signal output by the infrared receiving module is prevented from being distorted, and the accuracy of infrared detection is reduced.

Description

Technical Field

[0001] This utility model relates to the field of infrared detection technology, and in particular to an infrared detection circuit that prevents interference from external light sources. Background Technology

[0002] With the development of electronic technology, more and more products are using infrared sensors. As a key component of non-contact detection, infrared sensors achieve detection by receiving infrared signals emitted by target objects. However, in actual use, interference from external light sources such as sunlight and strong light can generate DC interference signals, causing infrared sensors to be falsely triggered or malfunction.

[0003] When performing infrared detection, existing infrared sensors either use filters to filter out external light sources or configure dedicated chips within the infrared sensor to filter out infrared signals. However, both methods increase the cost of using the product. Utility Model Content

[0004] To solve the above-mentioned technical problems, this utility model provides an infrared detection circuit that prevents interference from external light sources.

[0005] To achieve the above objectives, this utility model is implemented by the following technical solution:

[0006] An infrared detection circuit that prevents interference from external light sources includes:

[0007] An infrared emitting module, wherein the control terminal of the infrared emitting module is used to emit infrared light when a pulse control signal is received;

[0008] An infrared receiving module, which, upon receiving infrared light, converts it into a corresponding voltage signal;

[0009] An anti-interference module, the input terminal of which is connected to the output terminal of the infrared receiving module, is used to isolate DC interference signals generated by external light sources;

[0010] The signal processing module has its input terminal connected to the output terminal of the anti-interference module. The signal processing module is used to amplify the voltage signal and send it to the controller to determine whether it is infrared light emitted by the infrared emitting module.

[0011] By adopting the above technical solution, the DC interference signal generated by external light sources is isolated through the anti-interference module, avoiding the infrared sensor from being interfered with by external light sources such as sunlight or strong light, which could lead to malfunctions or abnormal operation. In addition, after isolating the DC interference signal, the voltage signal is amplified. Compared with the traditional circuit design of amplifying the voltage signal and then filtering out the DC interference signal, this avoids the DC interference signal being synchronously amplified and occupying the dynamic range of the amplifier, causing distortion of the voltage signal output by the infrared receiving module and reducing the accuracy of infrared detection. Moreover, the method of amplifying first and then filtering will also amplify the low-frequency noise of the external light source and superimpose it on the voltage signal output by the infrared receiving module. Even if some noise can be filtered out later, the amplified noise substrate cannot be completely eliminated, ultimately resulting in a decrease in the signal-to-noise ratio of the output signal and ineffective infrared detection.

[0012] The infrared detection circuit described above for preventing interference from external light sources further includes:

[0013] The controller has a pulse control terminal for outputting a pulse control signal to control the frequency of infrared light emission. The controller's signal receiving terminal receives the amplified voltage signal and compares it with the pulse control signal to determine whether the frequency of the amplified voltage signal is equal to the frequency of the pulse control signal. If so, it is infrared light emitted by the infrared emitting module.

[0014] As described above, an infrared detection circuit for preventing interference from external light sources includes an infrared emitting module comprising a switching transistor Q1, an infrared emitting diode IR-TX1, a first resistor R1, and a second resistor R7. The pulse control terminal of the controller is connected to one end of the second resistor R7, and the other end of the second resistor R7 is connected to the control electrode of the switching transistor Q1. The first conducting electrode of the switching transistor Q1 is grounded, and the second conducting electrode of the switching transistor Q1 is connected to the cathode of the infrared emitting diode IR-TX1. The anode of the infrared emitting diode IR-TX1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to a DC power supply.

[0015] As described above, in an infrared detection circuit designed to prevent interference from external light sources, the infrared receiving module includes:

[0016] An infrared receiver tube is provided, with its anode grounded and its cathode connected to the input terminal of the anti-interference module. The infrared receiver tube is used to convert the received infrared light into a corresponding voltage signal.

[0017] As described above, an infrared detection circuit for preventing interference from external light sources includes an anti-interference module comprising a first capacitor C1, the output terminal of the infrared receiving module being connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 being connected to the input terminal of the signal processing module.

[0018] As described above, an infrared detection circuit for preventing interference from external light sources includes an anti-interference module that further comprises a third resistor R2 and a fourth resistor R4. The first terminal of the first capacitor C1 is connected to the DC power supply via the third resistor R2, and the second terminal of the first capacitor C1 is connected to ground via the fourth resistor R4.

[0019] As described above, an infrared detection circuit for preventing interference from external light sources includes a signal processing module comprising an operational amplifier and an amplification factor setting unit. The output terminal of the anti-interference module is connected to the non-inverting input terminal of the operational amplifier, the inverting input terminal of the operational amplifier is electrically connected to the amplification factor setting unit, and the output terminal of the operational amplifier is connected to the signal receiving terminal of the controller.

[0020] As described above, an infrared detection circuit for preventing interference from external light sources includes a fifth resistor R5 and a sixth resistor R6 in the amplification setting unit. One end of the fifth resistor R5 is grounded, and the other end of the fifth resistor R5 is connected to the inverting input terminal of the operational amplifier. One end of the sixth resistor R6 is connected to the inverting input terminal of the operational amplifier, and the other end of the sixth resistor R6 is connected to the output terminal of the operational amplifier.

[0021] Compared with the prior art, the infrared detection circuit for preventing interference from external light sources proposed in this utility model has the following beneficial effects:

[0022] 1. The infrared detection circuit proposed in this utility model isolates the DC signal generated by external light sources through an anti-interference module, preventing the infrared sensor from malfunctioning or operating abnormally due to interference from external light sources such as sunlight or strong light. Furthermore, by isolating the DC interference signal before amplifying the voltage signal, compared to the traditional circuit design that amplifies the voltage signal and then filters out the DC interference signal, the DC interference signal is prevented from occupying the amplifier's dynamic range after synchronous amplification, thus avoiding distortion of the voltage signal output by the infrared receiving module 200 and reducing the accuracy of infrared detection. Moreover, the method of amplifying first and then filtering also amplifies low-frequency noise from external light sources, superimposing it onto the voltage signal output by the infrared receiving module 200. Even if some noise is subsequently filtered out, the amplified noise substrate cannot be completely eliminated, ultimately leading to a decrease in the signal-to-noise ratio of the output signal and hindering effective infrared detection.

[0023] 2. The anti-interference module proposed in this utility model utilizes the electrical characteristics of a capacitor to pass AC and block DC, which isolates the DC signal (interference signal) superimposed on the voltage signal caused by interference from external light sources. Only the pulse signal (useful signal) generated by the received infrared light can pass through, thereby isolating the DC interference signal generated by external light sources and avoiding false judgments by the infrared sensor, which could lead to malfunctions or abnormal operation of the litter box. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model, the accompanying drawings used in the description of the embodiments will be briefly introduced below.

[0025] Fig. 1 This is a block diagram illustrating the circuit principle structure of this utility model;

[0026] Fig. 2 This is a circuit diagram of the infrared emitting module of this utility model;

[0027] Fig. 3 This is a partial circuit diagram of other circuit modules of this utility model. Detailed Implementation

[0028] To make the technical problems solved, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be 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 present utility model and are not intended to limit the present utility model.

[0029] The infrared detection circuit proposed in the embodiments of this specification can be applied to devices that require infrared detection functions, including but not limited to open litter boxes and pet water fountains. The embodiments of this specification use open litter boxes as an example for illustration. As for applications to other devices, you can refer to this embodiment for implementation. This specification will not elaborate further here.

[0030] Please refer to Figs. 1 to 3As shown in the embodiment of this specification, an infrared detection circuit for preventing interference from external light sources is proposed, including an infrared emitting module 100, an infrared receiving module 200, an anti-interference module 300, and a signal processing module 400. The control terminal of the infrared emitting module 100 is used to emit infrared light when it receives a pulse control signal. The infrared receiving module 200 is used to convert the infrared light into a corresponding voltage signal when it receives the infrared light. The input terminal of the anti-interference module 300 is connected to the output terminal of the infrared receiving module 200. The anti-interference module 300 is used to isolate DC interference signals generated by external light sources. The input terminal of the signal processing module 400 is connected to the output terminal of the anti-interference module 300. The signal processing module 400 is used to amplify the voltage signal and send it to the controller to determine whether it is infrared light emitted by the infrared emitting module 100.

[0031] In this embodiment, the infrared detection circuit isolates the DC signal generated by external light sources through an anti-interference module, preventing the infrared sensor from malfunctioning or operating abnormally due to interference from external light sources such as sunlight or strong light. Furthermore, isolating the DC interference signal before amplifying the voltage signal avoids the problem of the DC interference signal occupying the amplifier's dynamic range, distorting the voltage signal output by the infrared receiving module 200, and reducing the accuracy of infrared detection. Additionally, the method of amplifying before filtering also amplifies low-frequency noise from external light sources, superimposing it on the voltage signal output by the infrared receiving module 200. Even if some noise is subsequently filtered out, the amplified noise substrate cannot be completely eliminated, ultimately reducing the signal-to-noise ratio of the output signal and hindering effective infrared detection.

[0032] Furthermore, as a preferred embodiment of this solution and not a limitation, the infrared detection circuit further includes a controller. The pulse control terminal of the controller is used to output a pulse control signal to control the frequency of infrared light emission. The signal receiving terminal of the controller is used to receive the amplified voltage signal and compare it with the pulse control signal to determine whether the frequency of the amplified voltage signal is equal to the frequency of the pulse control signal. If so, it is infrared light emitted by the infrared emitting module 100.

[0033] Specifically, the controller's pulse control terminal outputs a pulse control signal of a specific frequency to the infrared emitting module 100, driving the infrared emitting module 100 to emit pulsed infrared light at a frequency synchronized with the pulse control signal. After the controller's signal receiving terminal receives the amplified voltage signal, the controller compares the frequency of the received voltage signal with the frequency of its own output pulse control signal. If the frequencies are the same, it can be confirmed that the infrared light received by the infrared sensor is the infrared light emitted by the infrared emitting module 100. If the frequencies are not the same, it is determined that the infrared light received by the infrared sensor is interfered with by an external light source.

[0034] In this embodiment, the litter box uses the frequency of the voltage signal received by the controller to determine whether the infrared light received by the infrared sensor is the infrared light emitted by the infrared emitting module. This avoids the litter box from malfunctioning or malfunctioning when the infrared sensor receives infrared light that is interfered with by external light sources and determines that it has detected a valid signal. Furthermore, it eliminates the need for additional filters or dedicated chips, thus reducing the product's design cost.

[0035] It should be noted that the above controller can be implemented using, for example, MCU (Micro Controller Unit), DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array), SOC (System On Chip), etc., and this specification does not make any specific limitations.

[0036] Furthermore, as a preferred embodiment of this solution and not a limitation, the infrared emitting module 100 includes a switching transistor Q1, an infrared emitting diode IR-TX1, a first resistor R1, and a second resistor R7. The pulse control terminal (i.e., the MCU-PWM terminal) of the controller is connected to one end of the second resistor R7, and the other end of the second resistor R7 is connected to the control electrode of the switching transistor Q1. The first conducting electrode of the switching transistor Q1 is grounded, and the second conducting electrode of the switching transistor Q1 is connected to the cathode of the infrared emitting diode IR-TX1. The anode of the infrared emitting diode IR-TX1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to a DC power supply.

[0037] Specifically, when the control terminal of the switching transistor Q1 receives a specific frequency pulse control signal output from the pulse control terminal (MCU-PWM terminal) of the controller, the switching transistor Q1 is turned on, so that the first conducting terminal and the second conducting terminal of the switching transistor Q1 form a low impedance conducting channel. At this time, the cathode of the infrared emitting diode IR-TX1 is grounded through the switching transistor Q1, and the anode of the infrared emitting diode IR-TX1 is connected to the DC power supply (VCC), forming a conducting loop. The infrared emitting diode IR-TX1 emits infrared light according to the frequency of the pulse control signal.

[0038] In this embodiment, the infrared emitting diode IR-TX1 is controlled by the switching transistor Q1 to emit infrared light, thereby avoiding the continuous power supply of the infrared emitting diode IR-TX1 to emit light, reducing the power consumption of the infrared detection circuit, and extending its working time on the litter box.

[0039] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the infrared receiving module 200 includes an infrared receiving tube IR-RX1, the anode of the infrared receiving tube IR-RX1 is grounded, the cathode of the infrared receiving tube IR-RX1 is connected to the input terminal of the anti-interference module 300, and the infrared receiving tube IR-RX1 is used to convert the infrared light received into a corresponding voltage signal.

[0040] In this embodiment, when the infrared receiver IR-RX1 receives the infrared light emitted by the infrared emitter IR-TX1, it generates a voltage signal corresponding to the received infrared light. This voltage signal is a pulse signal (useful signal) generated by the received infrared light and a DC signal (interference signal) superimposed by interference from external light sources.

[0041] Furthermore, as a preferred embodiment of this solution and not a limitation thereof, the anti-interference module 300 includes a first capacitor C1, the output terminal of the infrared receiving module 200 is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to the input terminal of the signal processing module.

[0042] The first capacitor C1 is used to isolate DC interference signals generated by external light sources.

[0043] In this embodiment, the voltage signal generated by the infrared receiver tube IR-RX1, when passing through the first capacitor C1, utilizes the electrical characteristic of the capacitor to pass AC and block DC, thus isolating the DC signal (interference signal) superimposed on the voltage signal caused by external light source interference. Only the pulse signal (useful signal) generated by the received infrared light can pass through the first capacitor C1, thereby isolating the DC interference signal generated by the external light source and avoiding misjudgment by the infrared sensor, which could lead to malfunction or abnormal operation of the litter box.

[0044] In a preferred embodiment, the anti-interference module 300 further includes a third resistor R2 and a fourth resistor R4. The first terminal of the first capacitor C1 is connected to the DC power supply via the third resistor R2, and the second terminal of the first capacitor C1 is connected to ground via the fourth resistor R4.

[0045] In this embodiment, the fourth resistor R4 and the first capacitor C1 form an RC filter circuit to suppress low-frequency interference signals in the pulse signal and suppress interference noise in the infrared detection circuit. This prevents interference noise from being superimposed on the pulse signal, causing signal distortion and misjudgment by the infrared sensor, which could lead to malfunctions or abnormal operation of the litter box.

[0046] Furthermore, as a preferred embodiment of this solution and not a limitation, the signal processing module 400 includes an operational amplifier U1A and an amplification factor setting unit 410. The output terminal of the anti-interference module 300 is connected to the non-inverting input terminal of the operational amplifier U1A, the inverting input terminal of the operational amplifier U1A is electrically connected to the amplification factor setting unit 410, and the output terminal of the operational amplifier U1A is connected to the signal receiving terminal (i.e., the MCU-I / O terminal) of the controller.

[0047] In a preferred embodiment, the amplification factor setting unit 410 includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is grounded, and the other end of the fifth resistor R5 is connected to the inverting input terminal of the operational amplifier U1A. One end of the sixth resistor R6 is connected to the inverting input terminal of the operational amplifier U1A, and the other end of the sixth resistor R6 is connected to the output terminal of the operational amplifier U1A.

[0048] Specifically, when the non-inverting input of the operational amplifier U1A receives the pulse signal after filtering out the DC interference signal, it amplifies the signal according to the amplification factor set by the amplification factor setting unit 410, and sends it to the signal receiving end (MCU-I / O end) of the controller for judgment to confirm whether it is infrared light emitted by the infrared emitting module 100.

[0049] It should be noted that the amplification factor setting unit 410 mentioned above is determined by the resistance values ​​of resistors R5 and R6. The specific amplification factor calculation formula is as follows: The specific magnification should be set according to the actual testing requirements; this manual does not provide a specific limit.

[0050] In this embodiment, since the voltage signal converted from the infrared light received by the infrared receiver tube is relatively weak and cannot be effectively recognized by the controller, the operational amplifier U1A amplifies it to the input range of the controller according to the set amplification factor to avoid insufficient voltage signal amplitude, which would prevent the controller from making an effective judgment and ensure the detection sensitivity and detection accuracy of the infrared sensor.

[0051] Those skilled in the art should understand that the above description is one embodiment provided in conjunction with specific content, and does not imply that the specific implementation of this utility model is limited to these descriptions. Furthermore, due to differences in industry naming conventions, it is not limited to the above names or English names. Any methods or structures similar to or identical to those of this utility model, or any technical deductions or substitutions made based on the concept of this utility model, should be considered within the scope of protection of this utility model.

Claims

1. An infrared detection circuit that prevents interference from external light sources, characterized in that, include: An infrared emitting module, wherein the control terminal of the infrared emitting module is used to emit infrared light when a pulse control signal is received; An infrared receiving module, which, upon receiving infrared light, converts it into a corresponding voltage signal; An anti-interference module, the input terminal of which is connected to the output terminal of the infrared receiving module, is used to isolate DC interference signals generated by external light sources; The signal processing module has its input terminal connected to the output terminal of the anti-interference module. The signal processing module is used to amplify the voltage signal and send it to the controller to determine whether it is infrared light emitted by the infrared emitting module.

2. The infrared detection circuit for preventing interference from external light sources according to claim 1, characterized in that, Also includes: The controller has a pulse control terminal for outputting a pulse control signal to control the frequency of infrared light emission. The controller's signal receiving terminal receives the amplified voltage signal and compares it with the pulse control signal to determine whether the frequency of the amplified voltage signal is equal to the frequency of the pulse control signal. If so, it is infrared light emitted by the infrared emitting module.

3. An infrared detection circuit for preventing interference from external light sources according to claim 1 or 2, characterized in that, The infrared emitting module includes a switch Q1, an infrared emitting diode IR-TX1, a first resistor R1, and a second resistor R7. The pulse control terminal of the controller is connected to one end of the second resistor R7, and the other end of the second resistor R7 is connected to the control electrode of the switch Q1. The first conducting electrode of the switch Q1 is grounded, and the second conducting electrode of the switch Q1 is connected to the cathode of the infrared emitting diode IR-TX1. The anode of the infrared emitting diode IR-TX1 is connected to one end of the first resistor R1, and the other end of the first resistor R1 is connected to a DC power supply.

4. The infrared detection circuit for preventing interference from external light sources according to claim 1, characterized in that, The infrared receiving module includes: An infrared receiver tube is provided, with its anode grounded and its cathode connected to the input terminal of the anti-interference module. The infrared receiver tube is used to convert the received infrared light into a corresponding voltage signal.

5. The infrared detection circuit for preventing interference from external light sources according to claim 1, characterized in that, The anti-interference module includes a first capacitor C1. The output terminal of the infrared receiving module is connected to the first terminal of the first capacitor C1, and the second terminal of the first capacitor C1 is connected to the input terminal of the signal processing module.

6. The infrared detection circuit for preventing interference from external light sources according to claim 5, characterized in that, The anti-interference module also includes a third resistor R2 and a fourth resistor R4. The first terminal of the first capacitor C1 is connected to the DC power supply via the third resistor R2, and the second terminal of the first capacitor C1 is connected to ground via the fourth resistor R4.

7. The infrared detection circuit for preventing interference from external light sources according to claim 2, characterized in that, The signal processing module includes an operational amplifier and an amplification factor setting unit. The output terminal of the anti-interference module is connected to the non-inverting input terminal of the operational amplifier, the inverting input terminal of the operational amplifier is electrically connected to the amplification factor setting unit, and the output terminal of the operational amplifier is connected to the signal receiving terminal of the controller.

8. The infrared detection circuit for preventing interference from external light sources according to claim 7, characterized in that, The amplification factor setting unit includes a fifth resistor R5 and a sixth resistor R6. One end of the fifth resistor R5 is grounded, and the other end of the fifth resistor R5 is connected to the inverting input terminal of the operational amplifier. One end of the sixth resistor R6 is connected to the inverting input terminal of the operational amplifier, and the other end of the sixth resistor R6 is connected to the output terminal of the operational amplifier.

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