Background suppression photoelectric sensor

Abstract

The utility model relates to the technical field of photoelectric sensors, in particular to a background suppression photoelectric sensor which comprises an MCU, a light source transmitting circuit, a light signal receiving circuit and an ambient light detection circuit, the light source transmitting circuit controls transmitting of light signals through the MCU, and the light signal receiving circuit converts the received light signals into electric signals and transmits the electric signals to the MCU; the ambient light detection circuit is used for detecting ambient light and converting the ambient light into an electric signal; and meanwhile, the system also comprises a signal amplification circuit, a differential amplification circuit, a reverse amplification circuit and an induction signal output and LED display function. The technical effects of effectively overcoming ambient light interference and improving the detection precision and sensitivity are achieved, meanwhile, the signal processing process is optimized, and the stability and adaptability of equipment are enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of sensors, in particular to a background suppression photoelectric sensor. BACKGROUND

[0002] The diffuse reflection photoelectric sensor puts the signal emitter and the signal receiver in the same sensor. The light emitted by the signal emitter is diffusely reflected on the object to be detected, and the reflected light is received by the receiver, and then converted by the circuit to output the optical signal as an electrical signal. It is usually used in short distance detection scenes.

[0003] The conventional diffuse reflection photoelectric sensor has a large difference in sensing distance for different colors of objects in the sensing range due to the difference in reflectivity of different colors of objects. The background suppression photoelectric sensor is not affected by the color of the workpiece.

[0004] The background suppression photoelectric sensor generally uses a double photodiode to receive the diffusely reflected signal and sends it to the MCU (microcontroller) ADC (analog / digital converter) for sampling and judgment. However, if there is a lot of ambient light in the working scene, these ambient lights will interfere with the photoelectric sensor and cause the photodiode to receive the sensing, which may cause misjudgment and reduce accuracy and stability. CONTENT OF THE INVENTION

[0005] The present application provides a background suppression photoelectric sensor with high stability and anti-interference. The following technical solutions are adopted:

[0006] A background suppression photoelectric sensor, comprising:

[0007] MCU;

[0008] A light source emitting circuit for emitting a light signal, electrically connected to the MUC to control the on-off of the light source driving circuit;

[0009] A light signal receiving circuit having a first light signal receiving tube for converting the light signal into an electrical signal, the light signal receiving circuit being electrically connected to the MCU;

[0010] An ambient light detection circuit having a second light signal receiving tube for receiving ambient light and converting it into an electrical signal, the ambient light detection circuit being electrically connected to the MCU.

[0011] By adopting the technical scheme, the sensor transmits light signals through the MCU-controlled light source transmitting circuit, converts the reflected light signals into electric signals through the first light signal receiving tube in the light signal receiving circuit, and detects and converts the ambient light into electric signals through the second light signal receiving tube in the ambient light detection circuit. This design effectively distinguishes the light signals reflected by the target object from the ambient light interference, thereby improving the stability and anti-interference performance of the sensor.

[0012] Preferably, the first light signal receiving tube comprises a first photodiode and a second photodiode, and the first photodiode and the second photodiode are connected in parallel.

[0013] By adopting the technical scheme, the first light signal receiving tube is composed of the first photodiode and the second photodiode connected in parallel, which can effectively improve the sensitivity and stability of light signal receiving. The parallel structure enables the two photodiodes to simultaneously receive the diffuse reflection light signals and convert them into electric signals, thereby enhancing the signal strength, reducing the influence caused by the performance fluctuation of a single photodiode, and improving the reliability of overall detection.

[0014] Preferably, a signal amplification circuit is further arranged between the light signal receiving circuit and the MCU, the light signal receiving circuit is electrically connected with the input end of the signal amplification circuit, and the MCU is electrically connected with the output end of the signal amplification circuit.

[0015] By adopting the technical scheme, the signal amplification circuit can effectively amplify the weak electric signals output by the light signal receiving circuit, thereby improving the recognition accuracy of the MCU on the signals. This helps to enhance the sensitivity and stability of the sensor and reduce the misjudgment problem caused by too weak signals.

[0016] Preferably, the signal amplification circuit comprises a differential amplification circuit and a reverse amplification circuit.

[0017] The first photodiode is electrically connected with the negative feedback input end of the differential amplification circuit, and the second photodiode is electrically connected with the positive feedback input end of the differential amplification circuit.

[0018] The output end of the differential amplification circuit is electrically connected with the negative feedback input end of the reverse amplification circuit, the second photodiode is connected with the positive feedback input end of the reverse amplification circuit, and the output end of the reverse amplification circuit is electrically connected with the MCU.

[0019] By adopting the technical scheme, the differential amplification circuit can effectively suppress common-mode interference signals and improve the signal-to-noise ratio of the signals, thereby enhancing the anti-interference capability of the sensor. The reverse amplification circuit further amplifies the signals, thereby improving the sensitivity and output stability of the signals. The combination of the two enables the background-restrained photoelectric sensor to maintain high detection accuracy and stability under complex ambient light conditions.

[0020] Preferably, a coupling capacitor is arranged between the output end of the differential amplification circuit and the input end of the reverse amplification circuit.

[0021] By adopting the above technical solution, the coupling capacitor is arranged between the output end of the differential amplification circuit and the input end of the reverse amplification circuit, which can effectively isolate direct current from alternating current, avoid the interference of direct current components on the subsequent reverse amplification circuit, and thus improve the precision and stability of signal processing.

[0022] Preferably, the signal reverse amplification circuit further has a clamping diode for clamping the output signal.

[0023] By adopting the above technical solution, after adding the clamping diode, the voltage range of the output signal can be limited to prevent circuit damage caused by overvoltage, while ensuring the stability and reliability of the output signal. Specifically, the clamping diode effectively protects the subsequent circuit from abnormal voltage impact, improving the stability of the entire signal amplification circuit.

[0024] Preferably, the light source emission circuit includes a laser diode and a driving circuit, and the driving circuit is electrically connected with the MCU.

[0025] By adopting the above technical solution, the laser diode as the core component of the light source emission circuit can emit stable and directional light signals, and the electrical connection of the driving circuit with the MCU realizes accurate control of the on-off of the light source emission circuit.

[0026] Preferably, it further includes an induction signal output circuit and a trigger indication circuit, and both are electrically connected with the MCU.

[0027] By adopting the above technical solution, the background suppression photoelectric sensor can output the detection results in the form of electrical signals through the induction signal output circuit, and at the same time, the trigger indication circuit can intuitively display the detection state, thereby improving the practicality of the device and the user interaction experience.

[0028] In summary, the present application includes at least one of the following beneficial technical effects:

[0029] 1. By arranging the ambient light detection circuit and the light signal receiving circuit to receive ambient light and reflected light signals respectively and transmitting them to the MCU for processing, the environmental light interference is effectively reduced, and the stability and anti-interference of the sensor are significantly improved.

[0030] 2. The light source emission circuit is controlled by the MCU, and the light signal receiving circuit realizes accurate light signal emission and reception, ensuring the consistency of the sensing distance for different color objects, and solving the problem of sensing distance fluctuation caused by color difference of objects in traditional sensors.

[0031] 3. The cooperation of the ambient light detection circuit and the light signal receiving circuit optimizes the signal processing flow, improves the detection accuracy, and especially maintains reliable detection performance under strong ambient light interference. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 is a circuit module structure schematic diagram of the background suppression photoelectric sensor in the embodiment of the application;

[0033] Figure 2 is a circuit structure schematic diagram of the light source emitting circuit in the embodiment of the application;

[0034] Figure 3 is a structure schematic diagram of the light signal receiving circuit and the signal amplification circuit in the embodiment of the application.

[0035] Marked in the drawing: 1, MCU; 2, light source emitting circuit; 21, laser diode; 22, driving circuit; 3, light signal receiving circuit; 31, first photodiode; 32, second photodiode; 4, ambient light detection circuit; 41, second light signal receiving tube; 42, signal amplifier; 5, signal amplification circuit; 51, differential amplification circuit; 52, reverse amplification circuit; 53, reference voltage circuit; 6, coupling capacitor; 7, clamping diode; 8, induced signal output circuit; 9, trigger indication circuit. DETAILED DESCRIPTION

[0036] The following will be described in detail in combination with the accompanying Figures 1-3 The application is further described in detail.

[0037] The background suppression photoelectric sensor provided by the application refers to Figure 1 , comprising a microprocessor unit MCU1, a light source emitting circuit 2, a light signal receiving circuit 3 and an ambient light detection circuit 4, wherein the light source emitting circuit 2 is used for emitting a light signal; the light signal receiving circuit 3 is used for converting the light signal into an electric signal, and the ambient light detection circuit 4 is used for receiving ambient light and converting the ambient light into an electric signal. The light source emitting circuit 2, the light signal receiving circuit 3 and the ambient light detection circuit 4 are electrically connected with the MCU1.

[0038] Specifically, the MCU1 comprises a microprocessor and a related memory module. The microprocessor can be a high-performance ARM architecture processor or a single-chip microcomputer, etc., and the memory module can be selected from EEPROM, Flash and other non-volatile memory devices, which are used for storing user data, program code and running data.

[0039] Referring to Figure 2The light source emitting circuit 2 comprises a laser diode 21 and a driving circuit 22, and the driving circuit 22 is electrically connected with the MCU 1. Specifically, the driving circuit 22 is composed of a resistor R1, a capacitor C2, a resistor R2, a triode Q1 and a resistor R4. The MCU 1 can control the opening and closing of the light emitting tube D1 by controlling the IR. The light emitting tube is selected as the laser diode 21, which has high brightness and stable output characteristics.

[0040] With reference to Figure 3 The light signal receiving circuit 3 comprises a first light signal receiving tube. The first light signal receiving tube comprises a first photodiode 31 and a second photodiode 312. The first photodiode 31 and the second photodiode 312 are both PIN type photodiodes made of silicon-based materials, and have the characteristics of fast response and high sensitivity.

[0041] Further, the light signal receiving circuit 3 and the MCU 1 are further provided with a signal amplification circuit 5. The signal amplification circuit 5 comprises a differential amplification circuit 51 and a reverse amplification circuit 52. The first photodiode 31 is electrically connected with the negative feedback input end of the differential amplification circuit 51, and the second photodiode 312 is electrically connected with the positive feedback input end of the differential amplification circuit 51; the output end of the differential amplification circuit 51 is electrically connected with the negative feedback input end of the reverse amplification circuit 52; the second photodiode 312 is connected with the positive feedback input end of the reverse amplification circuit 52, and the output end of the reverse amplification circuit 52 is electrically connected with the MCU 1.

[0042] Further, the signal amplification circuit 5 is further provided with a reference voltage circuit 53, which is specifically composed of a resistor R9 and a resistor R10. The reference voltage circuit 53 is electrically connected with the positive feedback input ends of the differential amplification circuit 51 and the reverse amplification circuit 52, so as to provide a reference voltage.

[0043] A coupling capacitor 6 is arranged between the output end of the differential amplification circuit 51 and the negative feedback input end of the reverse amplification circuit 52. The coupling capacitor 6 plays a role of passing alternating current and blocking direct current, preventing direct current components from entering the subsequent cascade circuit, and reducing the influence of high-frequency noise.

[0044] The reverse amplification circuit 52 further has a clamping diode 7 for clamping the output signal. The clamping diode 7 is arranged between the negative feedback input end and the output end of the reverse amplification circuit 52, and is used for clamping the amplified signal.

[0045] The ambient light detection circuit 4 comprises a second light signal receiving tube 41 and a signal amplifier 42, and the second light signal receiving tube 41, the signal amplifier 42 and the MCU 1 are sequentially electrically connected. The second light signal receiving tube 41 also adopts a PIN type photodiode, but its working wavelength range covers a wider range. For collecting ambient light, the current ambient light condition such as ambient light noise and ambient light intensity can be obtained. The signal-to-noise ratio can be improved, more information can be fused in the algorithm, the anti-interference ability of the sensor can be improved, and the accuracy and stability of the sensor can be improved.

[0046] The signal amplifier 42 adopts a common operational amplifier on the market, so as to amplify the ambient light signal.

[0047] Further, the photoelectric sensor of the present application increases an induction signal output circuit 8 and a trigger indication circuit 9. The induction signal output circuit 8 is electrically connected with the MCU 1, and is used for outputting the detection result to an external device in the form of switching value or analog value. The trigger indication circuit 9 is also electrically connected with the MCU 1, and is used for directly displaying the working state and the detection result of the sensor.

[0048] Specifically, the induction signal output circuit 8 comprises a relay module and a digital interface module. The relay module is responsible for converting the control signal output by the MCU 1 into a strong electric contact signal, and is suitable for the electrical control system of an industrial site. The digital interface module supports RS485, Modbus and other communication protocols, and is convenient for interconnection with an upper computer or other intelligent devices.

[0049] The trigger indication circuit 9 comprises a plurality of high-brightness LED lamps and a driving chip. The high-brightness LED lamps are divided into red, green and blue three colors, and respectively represent three states of fault, normal and alarm. The driving chip controls the on-off and flashing frequency of each LED lamp according to the instruction of the MCU 1, so as to realize clear and intuitive state indication.

[0050] In addition, in order to facilitate the emission and reception of light signals, a receiving lens is additionally arranged at the first light signal receiving tube, and a transmitting lens is additionally arranged at the laser diode 21.

[0051] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application, so that: any equivalent changes made according to the structure, shape, principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A background rejection photosensor, characterized by, The application relates to a light source detection circuit, which comprises the following parts: an MCU (1); a light source emission circuit (2) for emitting a light signal, which is electrically connected with the MCU to control the on-off of a light source driving circuit (22); a light signal receiving circuit (3) with a first light signal receiving tube for converting the light signal into an electric signal, which is electrically connected with the MCU (1); an ambient light detection circuit (4) with a second light signal receiving tube (41) for receiving ambient light and converting the ambient light into an electric signal, which is electrically connected with the MCU (1).

2. The background suppression photodetector of claim 1, wherein, The first light signal receiving tube comprises a first photodiode (31) and a second photodiode (32), and the first photodiode (31) is electrically connected with the MCU (1).

3. The background suppression photodetector of claim 2, wherein, A signal amplification circuit (5) is further arranged between the light signal receiving circuit (3) and the MCU (1), the light signal receiving circuit (3) is electrically connected with the input end of the signal amplification circuit (5), and the MCU (1) is electrically connected with the output end of the signal amplification circuit (5).

4. The background suppression photodetector of claim 3, wherein, The signal amplification circuit (5) comprises a differential amplification circuit (51) and a reverse amplification circuit (52). The first photodiode (31) is electrically connected with the negative feedback input end of the differential amplification circuit (51), and the second photodiode (32) is electrically connected with the positive feedback input end of the differential amplification circuit (51). The output end of the differential amplification circuit (51) is electrically connected with the negative feedback input end of the reverse amplification circuit (52), the second photodiode (32) is electrically connected with the positive feedback input end of the reverse amplification circuit (52), and the output end of the reverse amplification circuit (52) is electrically connected with the MCU (1).

5. The background suppression photodetector of claim 4, wherein, A coupling capacitor (6) is arranged between the output end of the differential amplification circuit (51) and the input end of the reverse amplification circuit (52).

6. The background suppression photodetector of claim 4, wherein, The signal reverse amplification circuit (52) further has a clamping diode (7) for clamping the output signal.

7. The background suppression photodetector of claim 1, wherein, The light source emission circuit (2) comprises a laser diode (21) and a driving circuit (22), and the driving circuit (22) is electrically connected with the MCU (1).

8. The background suppression photodetector of claim 1, wherein, The application further comprises an inductive signal output circuit (8) and a trigger indication circuit (9), and both are electrically connected with the MCU (1).

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