Photoelectric sensor and constant light control circuit of light source thereof

Abstract

The utility model provides a photoelectric sensor and a light source constant light control circuit thereof, the photoelectric sensor is provided with a light source and a photoelectric detector, the circuit comprises a main control circuit used for outputting a control signal to control the light source constant current control circuit, and receiving a feedback signal of a light intensity feedback circuit to control the light source constant current control circuit. Adjusting the control signal to keep the light intensity of the light source unchanged; the light source constant current control circuit is used for performing constant current control on the light source; and the light intensity feedback circuit is used for processing the current signal converted by the photoelectric detector and feeding back the current signal to the main control circuit. According to the utility model, the light source light intensity change of the photoelectric sensor can be found in time, and the adjustment can be responded in time, so that the light source intensity of the photoelectric sensor remains unchanged, thereby ensuring the measurement precision of the photoelectric sensor.

Description

Technical Field

[0001] The utility model relates to the technical field of photoelectric sensor control, in particular to a photoelectric sensor and a constant light control circuit of a light source thereof. Background Art

[0002] Photoelectric sensors convert light energy into electrical energy, effectively converting optical information into electrical information. They can be used to detect non-electrical quantities that directly cause changes in light intensity, such as light intensity, illuminance, radiation temperature measurement, and gas composition analysis. They can also be used to detect other non-electrical quantities that can be converted into changes in light intensity, such as part diameter, surface roughness, strain, displacement, vibration, velocity, acceleration, and to identify an object's shape and operating status.

[0003] Photoelectric sensors typically consist of a light source, a photodetector, and a detection circuit. Important parameters of a light source include its radiation characteristics, spectral characteristics, photoelectric conversion characteristics, and environmental characteristics (such as thermal coefficient, long-term drift, and aging). In the actual use of a photoelectric sensor, the light intensity received by the sensor may change over time, directly affecting the measurement results.

[0004] Therefore, it is necessary to perform constant light control on the light source of the photoelectric sensor to solve the above problems. Utility Model Content

[0005] In order to achieve the above-mentioned purpose and other advantages of the present invention, the first purpose of the present invention is to provide a constant light control circuit for a light source of a photoelectric sensor, wherein the photoelectric sensor is configured with a light source and a photodetector, including:

[0006] A main control circuit is used to output a control signal to control the constant current control circuit of the light source, and receive a feedback signal from the light intensity feedback circuit to adjust the control signal so that the light intensity of the light source remains unchanged;

[0007] The light source constant current control circuit is used to perform constant current control on the light source;

[0008] The light intensity feedback circuit is used to process the current signal converted by the photodetector and feed it back to the main control circuit.

[0009] Furthermore, the main control circuit includes:

[0010] Main controller, used to output digital signals.

[0011] Furthermore, the light source constant current control circuit includes:

[0012] A digital-to-analog converter, configured to receive the digital signal output by the main controller and output an analog voltage with reference to an external reference voltage;

[0013] A voltage divider circuit, used for dividing the analog voltage output by the digital-to-analog converter and inputting the divided voltage into a light source control circuit;

[0014] The light source control circuit is used to output a driving signal to control the current formed in the circuit where the light source is located;

[0015] The voltage feedback circuit is used to form a voltage feedback signal of the loop where the light source is located and return it to the light source control circuit to perform constant current control.

[0016] Furthermore, the light source constant current control circuit further includes:

[0017] The first filtering circuit is used to filter the output of the digital-to-analog converter.

[0018] Furthermore, the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, the inverting input terminal and the output terminal of the internal output operational amplifier of the digital-to-analog converter are connected to the light source control circuit via the first voltage divider resistor, and the first voltage divider resistor and the second voltage divider resistor are connected in series to ground.

[0019] Furthermore, the light source control circuit includes a comparator and an NMOS tube, the first voltage divider resistor is connected to the non-inverting input end of the comparator, the output end of the comparator is connected to the gate of the NMOS tube, the drain of the NMOS tube is connected to the negative electrode of the light source, the positive electrode of the light source is connected to the power supply, and the source of the NMOS tube is connected to the voltage feedback circuit.

[0020] Furthermore, the voltage feedback circuit includes a third voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to the source of the NMOS tube and the inverting input end of the comparator, and the other end of the third voltage-dividing resistor is grounded.

[0021] Furthermore, the first filtering circuit includes a first filtering capacitor, and the first filtering capacitor is connected in parallel with the second voltage-dividing resistor.

[0022] Furthermore, the light intensity feedback circuit includes:

[0023] a transimpedance amplifier circuit, configured to convert the current signal converted by the photodetector into a voltage signal;

[0024] The same-direction amplifier circuit is used to amplify the voltage signal output by the transimpedance amplifier circuit and feed it back to the main controller.

[0025] Furthermore, the light intensity feedback circuit further includes:

[0026] a second filtering circuit, configured to filter the output of the transimpedance amplifier circuit;

[0027] The third filtering circuit is used to filter the output of the same-direction amplifier circuit.

[0028] Furthermore, the transimpedance amplifier circuit includes a first operational amplifier, a first resistor, a first capacitor, a second resistor, and a third resistor. The first resistor and the first capacitor are connected in parallel between the inverting input and output of the first operational amplifier. The negative electrode of the photodetector is connected to the inverting input of the first operational amplifier, the positive electrode of the photodetector is grounded, and the second resistor and the third resistor are connected in series between the non-inverting input of the first operational amplifier and ground.

[0029] Furthermore, the non-inverting amplification circuit includes a second operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor. The output end of the first operational amplifier is connected to the non-inverting input end of the second operational amplifier via the fourth resistor. The fifth resistor is connected between the inverting input end and the output end of the second operational amplifier. The sixth resistor is connected between the inverting input end and the ground of the second operational amplifier. The output end of the second operational amplifier is connected to the ADC sampling unit of the main controller.

[0030] Furthermore, the second filtering circuit includes a first filtering resistor and a second filtering capacitor, the first filtering resistor is connected between the output end of the first operational amplifier and the fourth resistor, one end of the second filtering capacitor is connected between the first filtering resistor and the fourth resistor, and the other end of the second filtering capacitor is grounded.

[0031] Furthermore, the third filtering circuit includes a second filtering resistor and a third filtering capacitor, the second filtering resistor is connected between the output end of the second operational amplifier and the ADC sampling unit of the main controller, one end of the third filtering capacitor is connected between the second filtering resistor and the ADC sampling unit of the main controller, and the other end of the third filtering capacitor is grounded.

[0032] The second object of the present utility model is to provide a photoelectric sensor, which uses the above-mentioned control circuit to perform constant light control on its light source.

[0033] Furthermore, the light source and the photodetector in the photoelectric sensor are packaged in the same photosensitive chip.

[0034] Compared with the prior art, the beneficial effects of the present invention are:

[0035] The present invention provides a photoelectric sensor and a constant light control circuit for its light source. The photoelectric sensor is equipped with a light source and a photodetector. The circuit includes: a main control circuit for outputting a control signal to control a constant current control circuit for the light source, and receiving a feedback signal from a light intensity feedback circuit to adjust the control signal so that the light intensity of the light source remains constant; the light source constant current control circuit for performing constant current control on the light source; and the light intensity feedback circuit for processing the current signal converted by the photodetector and feeding it back to the main control circuit. The present invention can promptly detect changes in the light intensity of the photoelectric sensor's light source and can promptly respond and adjust so that the light intensity of the photoelectric sensor remains constant, thereby ensuring the measurement accuracy of the photoelectric sensor.

[0036] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the description, the following is a detailed description of the preferred embodiments of the present invention with the accompanying drawings. The specific implementation methods of the present invention are given in detail in the following embodiments and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 This is a schematic diagram of the constant light control circuit of the photoelectric sensor light source;

[0039] Figure 2 This is a schematic diagram of the constant current control circuit of the light source;

[0040] Figure 3 Schematic diagram of light intensity feedback circuit;

[0041] Figure 4 This is the schematic diagram of the constant light control circuit of the photoelectric sensor light source;

[0042] Figure 5 This is the constant light control circuit diagram of the photoelectric sensor light source;

[0043] Figure 6 Schematic diagram of a photoelectric sensor;

[0044] Figure 7 Schematic diagram of the photosensitive chip. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0046] In the drawings, the shapes and dimensions may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like components.

[0047] In the following description, words such as center, thickness, height, length, front, back, rear, left, right, top, bottom, upper, lower, etc. are defined relative to the structure shown in the drawings. In particular, "height" is equivalent to the dimension from top to bottom, "width" is equivalent to the dimension from left to right, and "depth" is equivalent to the dimension from front to back. They are relative concepts and may therefore change accordingly depending on their different positions and different usage states. Therefore, these or other directions should not be interpreted as restrictive terms.

[0048] Terms referring to attachment, coupling, and the like (eg, "connected" and "attached") refer to structures being fixed or attached to one another, directly or indirectly, through intermediate structures, as well as movable or rigid attachments or relationships, unless expressly stated otherwise.

[0049] A photoelectric sensor converts light into electrical signals. Its operating principle is based on the reflection, refraction, absorption, or scattering of light. Common photoelectric sensors consist of three main components: a light source, a detection optical path, and a photodetector.

[0050] The light source of a photoelectric sensor is typically a light-emitting diode (LED) or laser diode. The light is transmitted through an optical path and then shines on the object being detected. The optical signal changes depending on the object's different light properties, such as reflection, transmission, or absorption.

[0051] The photodetector of a photoelectric sensor receives light signals from an object and converts them into electrical signals. Common photodetectors include photoresistors, photodiodes, and phototransistors. These detectors are sensitive to light intensity or wavelength and output electrical signals related to the light signal.

[0052] Depending on the application requirements, photoelectric sensors can adopt different working modes. The following are some common working modes:

[0053] Reflective photoelectric sensor: the light emitted by the light source irradiates on the detected object, and the object reflects the light back, and the photodetector receives the reflected light and generates an electrical signal. By detecting the intensity or time of the reflected light, the presence, position or motion state of the object can be determined.

[0054] Transmissive photoelectric sensor: composed of a transmitter and a receiver, the light emitted by the transmitter directly irradiates on the receiver. When the object passes through the optical axis, it will block the transmission of light, thereby causing the light signal received by the receiver to change, generating a corresponding electrical signal.

[0055] Transmissive photoelectric sensor: composed of a transmitter and a receiver, the light emitted by the transmitter directly irradiates on the receiver. When the object passes through the optical axis, it will block the transmission of light, thereby causing the light signal received by the receiver to change, generating a corresponding electrical signal.

[0056] Scattering photoelectric sensor: after the light irradiates on the detected object, scattering phenomenon occurs. The photodetector receives the scattered light and generates an electrical signal, and by analyzing the distribution and intensity of the scattered light, the surface characteristics, particle size or motion speed of the object can be detected.

[0057] Photoelectric sensor has the advantages of non-contact, fast response speed, high precision, good stability, etc., and is widely used in automatic control, industrial detection, security monitoring, smart home and other fields. For example, in water quality detection, photoelectric sensors can be used to measure various water quality indicators, including TOC, turbidity, color, pH value, metal ions and water hardness, etc.

[0058] The utility model takes the photoelectric sensor as the TOC sensor as an example for illustration, and should not be understood as a limitation on the type of photoelectric sensor.

[0059] TOC sensor is mainly based on ultraviolet light absorption method. Specifically, many organic matters dissolved in water have absorption effect on specific wavelength ultraviolet light (such as 254nm). Therefore, by measuring the absorption degree of these organic matters to ultraviolet light, the total amount of organic pollutants in water can be indirectly measured. In addition, in order to measure more accurately, part of the TOC sensor also adopts double-beam technology, that is, ultraviolet light and infrared light (such as 850nm) are used at the same time, to automatically compensate the influence of light path attenuation and turbidity, to ensure the stability and reliability of the measured value.

[0060] However, photoelectric sensors will be affected by various environmental factors (thermal coefficient, long-term drift and aging, etc.) during long-term use, resulting in performance degradation or even failure. Therefore, it is of great significance to improve the reliability of photoelectric sensors by controlling the constant light of their light sources.

[0061] For the convenience of description, the present invention uses the example of a TOC sensor using a light emitting diode (LED) as the light source and a photodiode as the photodetector for illustration, which should not be understood as limiting the type of photoelectric sensor.

[0062] Example 1

[0063] A constant light control circuit for a photoelectric sensor light source, such as Figure 6 As shown, the photoelectric sensor 1 is equipped with a light source 200 and a photoelectric detector 300. Figure 1 As shown, the constant light control circuit 100 of the photoelectric sensor light source includes:

[0064] The main control circuit 110 is used to output a control signal to control the constant current control circuit of the light source, and receive a feedback signal from the light intensity feedback circuit to adjust the control signal so that the light intensity of the light source remains unchanged;

[0065] If the light intensity of the TOC sensor's LED light source changes due to factors such as temperature or aging, while the control signal from the main control circuit 110 remains unchanged, the feedback signal from the light intensity feedback circuit will also change accordingly. When the main control circuit 110 detects this change in the feedback signal, it immediately responds by changing its control signal so that the feedback signal detected by the main control circuit 110 returns to its initial level. This means that the light intensity of the TOC sensor's LED light source remains unchanged.

[0066] The light source constant current control circuit 120 is used to perform constant current control on the light source;

[0067] The LED light source of the TOC sensor is turned on through the light source constant current control circuit 120, and a current is formed in the circuit where the LED light source is located, and circuit and constant current control are performed.

[0068] The light intensity feedback circuit 130 is used to process the current signal converted by the photodetector and feed it back to the main control circuit.

[0069] After the light source constant current control circuit 120 turns on the TOC sensor's LED light source, the TOC sensor's photodetector detects the LED's light intensity signal and converts it into a current signal in real time. When the LED's light intensity changes, the light intensity signal detected by the photodetector also changes, and the feedback signal from the light intensity feedback circuit also changes accordingly. When the main control circuit 110 detects a change in this feedback signal, it immediately responds by changing its control signal, returning the feedback signal detected by the main control circuit 110 to its original initial state. This means that the light intensity of the TOC sensor's LED light source remains unchanged.

[0070] It should be noted that Figure 1 The dashed lines with arrows in the middle represent light rays.

[0071] In some embodiments, as Figure 2 、 Figure 3 、 Figure 4 As shown, the main control circuit 110 includes:

[0072] The main controller 111 is configured to output digital signals.

[0073] Optionally, the main controller 111 adopts a micro control unit (MCU), also known as a single-chip microcomputer or a single-chip microcomputer. The MCU is a chip that integrates functions such as a microprocessor core, a memory, and a peripheral interface.

[0074] In the initial state, a digital precision signal is output based on the initial voltage value of the MCU.

[0075] In some embodiments, as Figure 2 、 Figure 4 As shown, the light source constant current control circuit 120 includes:

[0076] A digital-to-analog converter 121 is configured to receive the digital signal output by the main controller and output an analog voltage with reference to an external reference voltage;

[0077] To automatically control the TOC sensor's LED light source, the digital signal output by the MCU must be converted into an analog value based on a standard (or reference) value. The input of a digital-to-analog converter 121 (DAC) is connected to the output of the MCU. The DAC receives the MCU's digital signal and converts it. To achieve more accurate conversion results, a reference voltage (VREF) can be input to the DAC through a pin. The DAC then outputs a voltage based on this external reference voltage.

[0078] The MCU sends a driving digital signal to the DAC, which is stably converted into an analog signal. Figure 5 As shown, based on the DAC reference chip U16, it receives a digital precision signal of the initial voltage output value from the MCU and outputs the voltage with reference to the external reference voltage of 1.25V. Specifically, the DIN pin, SCLK pin, and SYNC pin of U16 are connected to the MOSI pin, SCLK pin, and SYNC pin of the MCU, respectively. The GND pin of U16 is grounded, the VDD pin of U16 is connected to the 3.3V power supply and grounded via C35, the VREF pin of U16 is connected to the 1.25V power supply, and the VFB pin and #OUT pin of U16 are connected to the voltage divider circuit 122.

[0079] It should be noted that Figure 4 The dashed line with an arrow in the middle represents light. Figure 4The solid line with an arrow in the middle represents the electrical signal. Figure 4 Solid lines without arrows represent wires.

[0080] A voltage divider circuit 122, configured to divide the analog voltage output by the digital-to-analog converter and input the divided voltage into a light source control circuit;

[0081] In order to obtain the required voltage, the output voltage of the DAC needs to be divided to control the light source control circuit 123 to turn on the LED light source of the TOC sensor. Figure 5 As shown, the voltage divider circuit includes a first voltage divider resistor R46 and a second voltage divider resistor R1, and the inverting input terminal of the internal output operational amplifier of the digital-to-analog converter (i.e., the VFB pin of U16) and the output terminal (i.e., the #OUT pin of U16) are connected to the light source control circuit via the first voltage divider resistor R46, and the first voltage divider resistor and the second voltage divider resistor R1 are connected in series to ground.

[0082] In order to filter out high-frequency noise in the circuit and obtain a more stable output signal, in some embodiments, the light source constant current control circuit further includes:

[0083] The first filtering circuit is used to filter the output of the digital-to-analog converter.

[0084] like Figure 5 As shown, the first filtering circuit includes a first filtering capacitor C2, and the first filtering capacitor C2 is connected in parallel with the second voltage-dividing resistor R1.

[0085] In summary, the output of the DAC reference chip U16 is filtered, stabilized, and divided by R46, R1, and C2 before being input into the light source control circuit 123.

[0086] The light source control circuit 123 is used to output a driving signal to control the current in the loop where the light source is located. The voltage feedback circuit 124 is used to generate a voltage feedback signal of the loop where the light source is located and return it to the light source control circuit for constant current control.

[0087] The MCU sends a driving digital signal to the DAC, which is stably converted into an analog signal and controls the current on the MOS tube through the comparator. Then, the MCU continues to adjust the size of the driving signal sent to the DAC to maintain the received light intensity signal unchanged. Figure 4 、 Figure 5As shown, the light source control circuit includes a comparator U15 and an NMOS transistor Q2. The first voltage-dividing resistor R46 is connected to the non-inverting input terminal of the comparator U15. The output terminal of the comparator U15 is connected to the gate of the NMOS transistor Q2 via C38 and R27 connected in parallel. C38 and R27 are connected in parallel and then grounded via R41. Pin 2 of the comparator U15 is grounded, and pin 5 is connected to VCC. A capacitor C1 is connected between the output terminal and the inverting input terminal of the comparator U15. The drain of the NMOS transistor Q2 is connected to the negative electrode of the light source UV, the positive electrode of the light source UV is connected to the power supply 9V, and the source of the NMOS transistor Q2 is connected to the voltage feedback circuit.

[0088] like Figure 4 、 Figure 5 As shown, the voltage feedback circuit includes a third voltage-dividing resistor R50, one end of the third voltage-dividing resistor R50 is connected to the source of the NMOS transistor Q2 and the inverting input end of the comparator U15, and the other end of the third voltage-dividing resistor R50 is grounded.

[0089] The comparator U15 outputs a driving signal to control the NMOS tube Q2 to turn on, the LED light source is turned on, and a current is formed in the loop. At this time, the third voltage divider resistor R50 forms a voltage feedback signal back to the comparator U15 to perform circuit and constant current control.

[0090] In some embodiments, as Figure 3 As shown, the light intensity feedback circuit 130 includes:

[0091] a transimpedance amplifier circuit 131, configured to convert the current signal converted by the photodetector into a voltage signal;

[0092] The non-inverting amplifier circuit 132 is used to amplify the voltage signal output by the transimpedance amplifier circuit and feed it back to the main controller.

[0093] When the LED light source changes, the signal received by the photodetector (PD) changes, and is processed by the operational amplifier and fed back to the MCU. Figure 4 、 Figure 5 As shown, the transimpedance amplifier circuit includes a first operational amplifier U14, a first resistor R15, a first capacitor C34, a second resistor R48, and a third resistor R49. The first resistor R15 and the first capacitor C34 are connected in parallel between the inverting input and output of the first operational amplifier U14. The negative electrode of the photodetector PD is connected to the inverting input of the first operational amplifier U14, the positive electrode of the photodetector PD is grounded, and the second resistor R48 and the third resistor R49 are connected in series between the non-inverting input of the first operational amplifier U14 and ground.

[0094] like Figure 4、 Figure 5 As shown, the non-inverting amplifier circuit includes a second operational amplifier U12, a fourth resistor R45, a fifth resistor R37, and a sixth resistor R40. The output end of the first operational amplifier U14 is connected to the non-inverting input end of the second operational amplifier U12 via the fourth resistor R45. The fifth resistor R37 is connected between the inverting input end and the output end of the second operational amplifier U12. The sixth resistor R40 is connected between the inverting input end and the ground of the second operational amplifier U12. The output end of the second operational amplifier U12 is connected to the ADC sampling unit (PD_SG) of the main controller.

[0095] Alternatively, as Figure 5 、 Figure 7 As shown, the light sources UV, IR and the photodetector PD are packaged in the same photosensor chip U5, which can effectively reduce environmental interference and the impact of chip consistency.

[0096] In order to suppress high-frequency noise and interference and improve signal quality, in some embodiments, the light intensity feedback circuit further includes:

[0097] a second filtering circuit, configured to filter the output of the transimpedance amplifier circuit;

[0098] The third filtering circuit is used to filter the output of the same-direction amplifier circuit.

[0099] like Figure 5 As shown, the second filtering circuit includes a first filtering resistor R44 and a second filtering capacitor C39. The first filtering resistor R44 is connected between the output end of the first operational amplifier U14 and the fourth resistor R45. One end of the second filtering capacitor C39 is connected between the first filtering resistor R44 and the fourth resistor R45, and the other end of the second filtering capacitor C39 is grounded.

[0100] like Figure 5 As shown, the third filtering circuit includes a second filtering resistor R42 and a third filtering capacitor C29. The second filtering resistor R42 is connected between the output end of the second operational amplifier U12 and the ADC sampling unit of the main controller. One end of the third filtering capacitor C29 is connected between the second filtering resistor R42 and the ADC sampling unit of the main controller, and the other end of the third filtering capacitor C29 is grounded.

[0101] The light intensity of the LED light source is received in real time by the photodetector PD and converted into a current signal. The current signal is converted into a voltage signal by the cross-group amplifier circuit and filtered by R44 and C39. The voltage signal is amplified by the same-direction amplifier circuit and filtered by R42 and C29 before entering the ADC acquisition unit of the MCU.

[0102] When the voltage signal of the control current sent by the MCU remains unchanged, if the state of the LED light source is affected by certain factors such as temperature aging, the light intensity changes, and the output signal of the same-direction amplifier circuit will also change. When the MCU detects the signal change, it immediately responds and changes the driving signal of the control current so that the signal value of the same-direction amplifier circuit read back by the MCU returns to its original initial state. In other words, it is considered that the light intensity of the LED light source of the circuit remains unchanged.

[0103] This embodiment provides a constant light control circuit for a photoelectric sensor light source. The photoelectric sensor is equipped with a light source and a photodetector. The circuit includes: a main control circuit for outputting a control signal to control a constant current control circuit for the light source, and receiving a feedback signal from a light intensity feedback circuit to adjust the control signal to maintain a constant light intensity for the light source; the light source constant current control circuit for performing constant current control on the light source; and a light intensity feedback circuit for processing the current signal converted by the photodetector and feeding it back to the main control circuit. This embodiment can promptly detect changes in the light intensity of the photoelectric sensor light source and promptly respond and adjust to maintain the light intensity of the photoelectric sensor light source, thereby ensuring the measurement accuracy of the photoelectric sensor.

[0104] Example 2

[0105] like Figure 6 As shown, a photoelectric sensor 1 employs the above-described constant light control circuit 100 for a photoelectric sensor light source to perform constant light control on its light source 200. A detailed description of the constant light control circuit 100 for the photoelectric sensor light source can be found in the corresponding description of the control circuit embodiment above and will not be repeated here. In some embodiments, the photoelectric sensor 1 can be used as a TOC sensor, while in other embodiments, it can be used as other photoelectric sensors that utilize a light source for spectral sampling and analysis.

[0106] Alternatively, as Figure 7 As shown, the light source 200 and the photodetector 300 in the photoelectric sensor 1 are packaged in the same photosensitive chip 400, which can effectively reduce environmental interference and the influence of chip consistency.

[0107] The constant light control circuit 100 of the photoelectric sensor light source of this embodiment may include:

[0108] A main control circuit is used to output a control signal to control the constant current control circuit of the light source, and receive a feedback signal from the light intensity feedback circuit to adjust the control signal so that the light intensity of the light source remains unchanged;

[0109] The light source constant current control circuit is used to perform constant current control on the light source;

[0110] The light intensity feedback circuit is used to process the current signal converted by the photodetector and feed it back to the main control circuit.

[0111] Based on the technical solution of the above embodiment, optionally, the main control circuit includes:

[0112] Main controller, used to output digital signals.

[0113] Based on the technical solution of the above embodiment, optionally, the light source constant current control circuit includes:

[0114] A digital-to-analog converter, configured to receive the digital signal output by the main controller and output an analog voltage with reference to an external reference voltage;

[0115] A voltage divider circuit, used for dividing the analog voltage output by the digital-to-analog converter and inputting the divided voltage into a light source control circuit;

[0116] The light source control circuit is used to output a driving signal to control the current formed in the circuit where the light source is located;

[0117] The voltage feedback circuit is used to form a voltage feedback signal of the loop where the light source is located and return it to the light source control circuit to perform constant current control.

[0118] Based on the technical solution of the above embodiment, optionally, the light source constant current control circuit further includes:

[0119] The first filtering circuit is used to filter the output of the digital-to-analog converter.

[0120] Based on the technical solution of the above embodiment, optionally, the voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor, the inverting input terminal and the output terminal of the internal output op amp of the digital-to-analog converter are connected to the light source control circuit via the first voltage divider resistor, and the first voltage divider resistor and the second voltage divider resistor are connected in series to ground.

[0121] Based on the technical solutions of the above embodiments, optionally, the light source control circuit includes a comparator and an NMOS tube, the first voltage divider resistor is connected to the non-inverting input terminal of the comparator, the output terminal of the comparator is connected to the gate of the NMOS tube, the drain of the NMOS tube is connected to the negative electrode of the light source, the positive electrode of the light source is connected to the power supply, and the source of the NMOS tube is connected to the voltage feedback circuit.

[0122] Based on the technical solution of the above embodiment, optionally, the voltage feedback circuit includes a third voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to the source of the NMOS tube and the inverting input end of the comparator, and the other end of the third voltage-dividing resistor is grounded.

[0123] Based on the technical solution of the above embodiment, optionally, the first filtering circuit includes a first filtering capacitor, and the first filtering capacitor is connected in parallel with the second voltage-dividing resistor.

[0124] Based on the technical solution of the above embodiment, optionally, the light intensity feedback circuit includes:

[0125] a transimpedance amplifier circuit, configured to convert the current signal converted by the photodetector into a voltage signal;

[0126] The same-direction amplifier circuit is used to amplify the voltage signal output by the transimpedance amplifier circuit and feed it back to the main controller.

[0127] Based on the technical solution of the above embodiment, optionally, the light intensity feedback circuit further includes:

[0128] a second filtering circuit, configured to filter the output of the transimpedance amplifier circuit;

[0129] The third filtering circuit is used to filter the output of the same-direction amplifier circuit.

[0130] Based on the technical solutions of the above embodiments, optionally, the transimpedance amplifier circuit includes a first operational amplifier, a first resistor, a first capacitor, a second resistor, and a third resistor. The first resistor and the first capacitor are connected in parallel between the inverting input and output of the first operational amplifier. The negative electrode of the photodetector is connected to the inverting input of the first operational amplifier, the positive electrode of the photodetector is grounded, and the second resistor and the third resistor are connected in series between the non-inverting input of the first operational amplifier and the ground.

[0131] Based on the technical solution of the above embodiment, optionally, the non-inverting amplification circuit includes a second operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor. The output end of the first operational amplifier is connected to the non-inverting input end of the second operational amplifier via the fourth resistor. The fifth resistor is connected between the inverting input end and the output end of the second operational amplifier. The sixth resistor is connected between the inverting input end and the ground of the second operational amplifier. The output end of the second operational amplifier is connected to the ADC sampling unit of the main controller.

[0132] Based on the technical solution of the above embodiment, optionally, the second filtering circuit includes a first filtering resistor and a second filtering capacitor, the first filtering resistor is connected between the output end of the first operational amplifier and the fourth resistor, one end of the second filtering capacitor is connected between the first filtering resistor and the fourth resistor, and the other end of the second filtering capacitor is grounded.

[0133] Based on the technical solution of the above embodiment, optionally, the third filtering circuit includes a second filtering resistor and a third filtering capacitor, the second filtering resistor is connected between the output end of the second operational amplifier and the ADC sampling unit of the main controller, one end of the third filtering capacitor is connected between the second filtering resistor and the ADC sampling unit of the main controller, and the other end of the third filtering capacitor is grounded.

[0134] This embodiment provides a photoelectric sensor that utilizes the aforementioned control circuit to achieve constant light control for its light source. This embodiment can promptly detect changes in the light intensity of the photoelectric sensor's light source and promptly respond and adjust the intensity to maintain the same intensity, thereby ensuring the photoelectric sensor's measurement accuracy.

[0135] The number of devices and processing scales described herein are used to simplify the description of the present invention. Applications, modifications and variations of the present invention will be apparent to those skilled in the art.

[0136] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with this field, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

[0137] It should also be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, commodity, or apparatus that includes a series of elements includes not only those elements but also other elements not explicitly listed, or includes elements inherent to such process, method, commodity, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not exclude the presence of other identical elements in the process, method, commodity, or apparatus that includes the element.

[0138] The various embodiments in this specification are described in a progressive manner. Similar parts between the various embodiments can be referred to in conjunction with each other. Each embodiment focuses on the differences between the other embodiments. In particular, the system embodiments are generally similar to the method embodiments, so the description is relatively simple. For relevant parts, refer to the description of the method embodiments.

[0139] The foregoing is merely an example of the present invention and is not intended to limit the present invention to one or more embodiments. It will be apparent to those skilled in the art that various modifications and variations may be made to the present invention to one or more embodiments. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention to one or more embodiments shall be included within the scope of the claims of the present invention to one or more embodiments.

Claims

1. A constant light control circuit for a photoelectric sensor light source, wherein the photoelectric sensor is equipped with a light source and a photodetector, characterized in that: include: A main control circuit is used to output a control signal to control the constant current control circuit of the light source, and receive a feedback signal from the light intensity feedback circuit to adjust the control signal so that the light intensity of the light source remains unchanged; The light source constant current control circuit is used to perform constant current control on the light source; The light intensity feedback circuit is used to process the current signal converted by the photodetector and feed it back to the main control circuit.

2. A constant light control circuit for a photoelectric sensor light source as claimed in claim 1, characterized in that: The main control circuit includes: Main controller, used to output digital signals.

3. A constant light control circuit for a photoelectric sensor light source as claimed in claim 2, characterized in that: The light source constant current control circuit comprises: A digital-to-analog converter, configured to receive the digital signal output by the main controller and output an analog voltage with reference to an external reference voltage; A voltage divider circuit, used for dividing the analog voltage output by the digital-to-analog converter and inputting the divided voltage into a light source control circuit; The light source control circuit is used to output a driving signal to control the current formed in the circuit where the light source is located; The voltage feedback circuit is used to form a voltage feedback signal of the loop where the light source is located and return it to the light source control circuit to perform constant current control.

4. A constant light control circuit for a photoelectric sensor light source as claimed in claim 3, characterized in that: The light source constant current control circuit further includes: The first filtering circuit is used to filter the output of the digital-to-analog converter.

5. The constant light control circuit for a photoelectric sensor light source according to claim 4, wherein: The voltage divider circuit includes a first voltage divider resistor and a second voltage divider resistor. The inverting input terminal and the output terminal of the internal output operational amplifier of the digital-to-analog converter are connected to the light source control circuit via the first voltage divider resistor. The first voltage divider resistor and the second voltage divider resistor are connected in series to ground.

6. The constant light control circuit for a photoelectric sensor light source according to claim 5, wherein: The light source control circuit includes a comparator and an NMOS tube. The first voltage divider resistor is connected to the non-inverting input end of the comparator, the output end of the comparator is connected to the gate of the NMOS tube, the drain of the NMOS tube is connected to the negative electrode of the light source, the positive electrode of the light source is connected to the power supply, and the source of the NMOS tube is connected to the voltage feedback circuit.

7. The constant light control circuit for a photoelectric sensor light source according to claim 6, wherein: The voltage feedback circuit includes a third voltage-dividing resistor, one end of the third voltage-dividing resistor is connected to the source of the NMOS tube and the inverting input end of the comparator, and the other end of the third voltage-dividing resistor is grounded.

8. The constant light control circuit for a photoelectric sensor light source according to claim 7, wherein: The first filtering circuit includes a first filtering capacitor, and the first filtering capacitor is connected in parallel with the second voltage-dividing resistor.

9. The constant light control circuit of a photoelectric sensor light source according to claim 2, characterized in that: The light intensity feedback circuit comprises: a transimpedance amplifier circuit, configured to convert the current signal converted by the photodetector into a voltage signal; The same-direction amplifier circuit is used to amplify the voltage signal output by the transimpedance amplifier circuit and feed it back to the main controller.

10. The constant light control circuit of a photoelectric sensor light source according to claim 9, characterized in that: The light intensity feedback circuit further includes: a second filtering circuit, configured to filter the output of the transimpedance amplifier circuit; The third filtering circuit is used to filter the output of the same-direction amplifier circuit.

11. The constant light control circuit of a photoelectric sensor light source according to claim 10, wherein: The transimpedance amplifier circuit includes a first operational amplifier, a first resistor, a first capacitor, a second resistor, and a third resistor. The first resistor and the first capacitor are connected in parallel between the inverting input and output of the first operational amplifier. The negative electrode of the photodetector is connected to the inverting input of the first operational amplifier, the positive electrode of the photodetector is grounded, and the second resistor and the third resistor are connected in series between the non-inverting input of the first operational amplifier and ground.

12. The constant light control circuit of a photoelectric sensor light source according to claim 11, wherein: The non-inverting amplifier circuit includes a second operational amplifier, a fourth resistor, a fifth resistor, and a sixth resistor. The output end of the first operational amplifier is connected to the non-inverting input end of the second operational amplifier via the fourth resistor. The fifth resistor is connected between the inverting input end and the output end of the second operational amplifier. The sixth resistor is connected between the inverting input end and the ground of the second operational amplifier. The output end of the second operational amplifier is connected to the ADC sampling unit of the main controller.

13. The constant light control circuit of a photoelectric sensor light source according to claim 12, characterized in that: The second filtering circuit includes a first filtering resistor and a second filtering capacitor. The first filtering resistor is connected between the output end of the first operational amplifier and the fourth resistor. One end of the second filtering capacitor is connected between the first filtering resistor and the fourth resistor, and the other end of the second filtering capacitor is grounded.

14. The constant light control circuit of a photoelectric sensor light source according to claim 12, wherein: The third filtering circuit includes a second filtering resistor and a third filtering capacitor. The second filtering resistor is connected between the output end of the second operational amplifier and the ADC sampling unit of the main controller. One end of the third filtering capacitor is connected between the second filtering resistor and the ADC sampling unit of the main controller, and the other end of the third filtering capacitor is grounded.

15. A photoelectric sensor, characterized in that: The control circuit according to any one of claims 1 to 14 is used to perform constant light control on the light source.

16. The photoelectric sensor according to claim 15, wherein: The light source and the photodetector in the photoelectric sensor are packaged in the same photosensitive chip.

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