A background rejection photosensor with improved dark area detection capability

Abstract

The utility model discloses a background suppression photoelectric sensor of improving dark area detection capability, including signal input module, signal signal amplification processing module, control module and output module: signal input module gathers target light signal and background light signal through double photodiode IV conversion unit respectively, signal amplification processing module adopts (A the algorithm of B) / (A+B) and restraines background common mode noise, and the variable gain amplifier and hysteresis control unit of collocation optimize signal quality, control module realizes the adaptive adjustment of gain, light source parameter and working mode, and output module completes detection signal output and overcurrent protection. The utility model effectively promoted the detection precision and stability of dark area weak target signal, can adapt to the dark area environment of different illumination conditions, and the structure is simple and universal, is applicable to the high -precision detection demand of industrial automation, commodity circulation storage, security monitoring and a plurality of fields.

Description

Technical Field

[0001] This utility model relates to photoelectric sensor technology, specifically to a background suppression photoelectric sensor that improves dark area detection capabilities. This sensor is suitable for scenarios requiring accurate detection in dark environments, such as object detection in industrial automated production lines, intelligent warehousing cargo positioning, and security monitoring intrusion detection. Background Technology

[0002] Photoelectric sensors achieve target detection by converting light signals into electrical signals, and are widely used in industrial production, smart devices, and other fields. In dark area detection scenarios, accurately distinguishing the target object from the background environment is a core requirement, but current technologies have significant shortcomings:

[0003] The intensity and distribution of ambient light (such as workshop lighting and natural light) are prone to change, which can strongly interfere with the detection signal, leading to a surge in signal noise. Traditional sensors, which use fixed-gain amplification or simple filtering, struggle to effectively separate the target signal from the ambient light signal. Weak target signals are easily drowned out by noise, resulting in low detection accuracy and a high false positive rate. Furthermore, the lack of a dynamic adjustment mechanism makes them unable to adapt to changes in illumination in different dark environments, resulting in poor adaptability and stability. These problems severely impact the application performance of photoelectric sensors in dark area detection scenarios and urgently need to be addressed. Utility Model Content

[0004] To overcome the shortcomings of the existing technology, the present invention aims to provide a background suppression photoelectric sensor that improves the detection capability in dark areas. This sensor addresses the technical pain points of existing photoelectric sensors in dark area detection, such as severe background light interference, weak target signals being easily submerged by noise, poor environmental adaptability, and insufficient detection accuracy and stability. By optimizing the sensor's module structure and signal processing logic, the present invention achieves accurate, stable, and reliable detection of target objects in dark environments. At the same time, it expands the sensor's application scenario adaptability to meet the actual needs of high-precision dark area detection in fields such as industrial automation, logistics warehousing, and security monitoring.

[0005] To achieve the above and other related objectives, the technical solution provided by this utility model is: a background suppression photoelectric sensor for improving dark area detection capability, comprising a signal input module, a signal amplification and processing module, a control module, and an output module; the signal input module is electrically connected to the signal amplification and processing module, and the control module is electrically connected to both the signal amplification and processing module and the output module.

[0006] The signal input module includes a PDA photodiode IV conversion unit and a PDB photodiode IV conversion unit, which are used to receive the light signal reflected from the target object and the ambient background light signal, respectively, and convert the light signal into a voltage signal.

[0007] The signal amplification and processing module includes an (AB) / (A+B) operation unit, a selection gate, a gain control unit, a hysteresis control unit, and a level detection unit. The (AB) / (A+B) operation unit receives the voltage signal output from the signal input module and performs calculations. The selection gate receives the processed signal and switches the operating mode. The gain control unit dynamically adjusts the gain of the signal output from the selection gate. The hysteresis control unit and the level detection unit sequentially perform stability processing and threshold detection on the gain-adjusted signal.

[0008] The control module includes an AD controller, a counter, a main logic unit, and an oscillator. The AD controller controls the switching of the operating modes of the selection gate. The counter counts the valid signals output by the level detection unit. The main logic unit receives signals from each module and generates control commands. The oscillator provides a timing reference.

[0009] The output module includes an output inverter, an overcurrent detector, and an LED driver unit. The output inverter converts the counter output signal and outputs it through the OUT terminal. The overcurrent detector monitors the current of the output circuit, and the LED driver unit drives the LED light source to emit light.

[0010] The preferred technical solution is that both the PDA photodiode IV conversion unit and the PDB photodiode IV conversion unit use transimpedance amplifiers to achieve current-to-voltage conversion.

[0011] The preferred technical solution is as follows: the gain control unit includes two variable gain amplifiers, AMP1 and AMP2, and the main logic unit dynamically adjusts the gain parameters of the two amplifiers according to the signal strength.

[0012] The preferred technical solution is that the hysteresis control unit is a hysteresis comparator, which forms a hysteresis range by setting upper and lower thresholds to avoid output jumps caused by slight signal fluctuations.

[0013] The preferred technical solution is that the control module further includes a STA status indicator light, which is a high-brightness LED with a viewing angle of up to 120°, used to display the working status of the sensor.

[0014] A preferred technical solution is that the output inverter is also connected to PN and INV signal processing units to optimize the compatibility and stability of the output signal.

[0015] The preferred technical solution is that the main logic unit is electrically connected to the LED driving unit, and the luminous intensity and frequency of the LED light source can be adjusted according to the ambient light intensity.

[0016] The preferred technical solution is that the processing cycle of the (AB) / (A+B) operation unit is 10μs, which is used to suppress background light common-mode noise in real time.

[0017] Due to the application of the above technical solution, the beneficial effects of this utility model are as follows:

[0018] Effective suppression of background light interference: By employing a dual photodiode design (PDA and PDB) to receive target and background signals respectively, and utilizing the (AB) / (A+B) algorithm to enhance the difference component, interference from ambient background light can be significantly suppressed. This algorithm addresses the common-mode characteristics of background light by using differential calculation and normalization processing to effectively extract the target signal, reducing the impact of background light on the detection results, enabling the sensor to maintain high detection accuracy even in complex lighting environments.

[0019] Adaptive gain control enhances detection sensitivity: The gain control unit, composed of AMP1 and AMP2, dynamically adjusts the gain according to the intensity of the input signal, effectively amplifying weak target signals in dark areas. In low-light environments, it automatically increases the gain to enhance the signal amplitude and prevent weak signals from being drowned out by noise. When the light intensity changes, it adaptively adjusts the gain to ensure the linear range of signal processing and improve the sensor's adaptability to different dark environments.

[0020] Hysteresis control enhances detection stability: The introduction of the HYS hysteresis comparator creates a hysteresis range during signal detection, effectively preventing false triggering and output oscillation caused by signal fluctuations. This allows the sensor to maintain a stable output state when faced with slight environmental changes or signal noise, improving the reliability of detection results.

[0021] Integrated control modules enable intelligent detection: The coordinated operation of control modules such as the AD controller, counter, and main logic unit enables intelligent adjustment of sensor operating parameters and automated control of the detection process. For example, based on the real-time detected ambient light intensity and signal strength, the operating mode of the selection gate, gain parameters, and LED light intensity are automatically adjusted, allowing the sensor to adapt to different dark area detection scenarios without manual intervention, thereby improving detection efficiency and accuracy.

[0022] Overcurrent protection ensures system safety: The overcurrent detector provides a reliable protection mechanism for the sensor circuit. When an overcurrent occurs in the output circuit, it can trigger the protection in time to prevent component damage, extend the service life of the sensor, and improve the safety and stability of the system.

[0023] Wide applicability: The technical solution of this utility model is not only suitable for dark environments with varying light intensities, but also capable of handling complex background light distribution. Through reasonable design of the parameters and control logic of each module, this sensor can be widely applied in various scenarios such as object detection on industrial production lines, cargo positioning in smart warehousing, and intrusion detection in security systems, demonstrating high practical value and market potential. Attached Figure Description

[0024] Figure 1 This is a circuit diagram of the photoelectric sensor involved in this utility model. Detailed Implementation

[0025] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0026] Please see Figure 1 It should be noted that in the description of this utility model, the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. These terms are used only for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance. The terms "horizontal," "vertical," and "suspended," etc., do not indicate that the component must be absolutely horizontal or suspended, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0028] Example:

[0029] like Figure 1As shown, according to an overall technical concept of this utility model, a background suppression photoelectric sensor with improved dark area detection capability is provided, including a signal input module, a signal amplification and processing module, a control module, and an output module; the signal input module is electrically connected to the signal amplification and processing module, and the control module is electrically connected to both the signal amplification and processing module and the output module.

[0030] The signal input module includes a PDA photodiode IV conversion unit and a PDB photodiode IV conversion unit, which are used to receive the light signal reflected from the target object and the ambient background light signal, respectively, and convert the light signal into a voltage signal.

[0031] The signal amplification and processing module includes an (AB) / (A+B) operation unit, a selection gate, a gain control unit, a hysteresis control unit, and a level detection unit. The (AB) / (A+B) operation unit receives the voltage signal output from the signal input module and performs calculations. The selection gate receives the processed signal and switches the operating mode. The gain control unit dynamically adjusts the gain of the signal output from the selection gate. The hysteresis control unit and the level detection unit sequentially perform stability processing and threshold detection on the gain-adjusted signal.

[0032] The control module includes an AD controller, a counter, a main logic unit, and an oscillator. The AD controller controls the switching of the operating modes of the selection gate, the counter counts the valid signals output by the level detection unit, the main logic unit receives signals from each module and generates control commands, and the oscillator provides a timing reference.

[0033] The output module includes an output inverter, an overcurrent detector, and an LED driver unit. The output inverter converts the counter output signal and outputs it through the OUT terminal. The overcurrent detector monitors the current of the output circuit, and the LED driver unit drives the LED light source to emit light.

[0034] like Figure 1 As shown, in an exemplary embodiment of this utility model, both the PDA photodiode IV conversion unit and the PDB photodiode IV conversion unit employ transimpedance amplifiers to achieve current-to-voltage conversion.

[0035] like Figure 1 As shown, in an exemplary embodiment of this utility model, the gain control unit includes two variable gain amplifiers, AMP1 and AMP2, and the main logic unit dynamically adjusts the gain parameters of the two amplifiers according to the signal strength.

[0036] like Figure 1 As shown, in an exemplary embodiment of this utility model, the hysteresis control unit is a hysteresis comparator, which forms a hysteresis range by setting upper and lower thresholds to avoid output jumps caused by minor signal fluctuations.

[0037] like Figure 1 As shown, in an exemplary embodiment of this utility model, the control module further includes a STA status indicator light, which is a high-brightness LED with a viewing angle of up to 120°, used to display the sensor's working status.

[0038] like Figure 1 As shown, in an exemplary embodiment of this utility model, the output inverter is further connected to PN and INV signal processing units to optimize the compatibility and stability of the output signal.

[0039] like Figure 1 As shown, in an exemplary embodiment of this utility model, the main logic unit is electrically connected to the LED driving unit, and the luminous intensity and frequency of the LED light source can be adjusted according to the ambient light intensity.

[0040] like Figure 1 As shown, in an exemplary embodiment of this utility model, the processing cycle of the (AB) / (A+B) operation unit is 10μs, which is used to suppress background light common-mode noise in real time.

[0041] Detailed signal processing flow:

[0042] Signal Input and IV Conversion: The PDA photodiode IV conversion unit and the PDB photodiode IV conversion unit convert the received optical signal into a current signal, respectively. The PDA photodiode mainly receives the light signal reflected back from the target object, which contains the target object's characteristic information and possibly some background light mixed in; the PDB photodiode is mainly used to receive the background light signal from the environment. These two current signals are input to the IV conversion unit, which converts the weak current signal into a voltage signal for subsequent signal processing. The IV conversion unit is usually implemented using a transimpedance amplifier. By properly designing the parameters of the transimpedance amplifier, it is ensured that small current changes can be accurately converted into voltage changes.

[0043] (AB) / (A+B) Operation Unit: The analog circuit algorithm of the (AB) / (A+B) operation unit processes the signal. The principle of this algorithm is that the response of the target signal differs between the PDA photodiode and the PDB photodiode, while the response of the background light signal is relatively similar in both. AB effectively suppresses common-mode background light noise because the signals generated by the background light on the two photodiodes are approximately the same, and subtraction significantly reduces this noise. Furthermore, A+B, used as the denominator for normalization, eliminates the influence of signal amplitude fluctuations caused by changes in light source intensity or differences in sensor sensitivity.

[0044] The AD controller-controlled selection gate circuit selects whether the sensor operates in dual-PD background suppression mode or single-PD reflective mode, enabling multi-purpose operation.

[0045] Gain Control: The signal output from the selection gate sequentially passes through AMP1 and AMP2 for SENS (sensitivity) gain control. AMP1 and AMP2 are variable gain amplifiers, and their gain parameters are dynamically adjusted by the subsequent control module based on the signal strength. Gain control amplifies weak signals to a suitable amplitude for subsequent processing. Depending on the dark environment, when the background light is strong but the target signal is weak, increasing the gain can enhance the detectability of the target signal; conversely, when the signal is strong, appropriately reducing the gain can prevent signal saturation and ensure the linear range of signal processing. The gain control process is a closed-loop feedback process. By monitoring the amplitude of the output signal in real time and adjusting the gains of AMP1 and AMP2, adaptive adjustment of the sensor sensitivity can be achieved.

[0046] Hysteresis Control and Level Detection: The signal after gain control is first connected to the MON (Monitoring Unit), which monitors the signal in real time. The signal is then transmitted to the HYS (Hysteresis Comparator) for hysteresis control and the Level Detector (Level Detection Unit). Hysteresis control introduces hysteresis characteristics during signal detection, preventing frequent jumps in the output signal due to minor signal fluctuations and improving the stability of the detection results. For example, output is triggered when the signal rises to a certain threshold, and output stops only when the signal falls below another lower threshold. The difference between the two thresholds forms the hysteresis interval, effectively suppressing false triggers caused by noise. The Level Detection Unit determines whether the signal has reached a preset detection level. When the signal level exceeds the set threshold, a corresponding detection signal is output.

[0047] Counter and Output Control: The detection signal output by the LevelDetector is connected to a Counter controlled by the STA. The counter is used to count the detected valid signals and determine whether a target object exists, as well as the number of target objects, their motion state, and other information based on the counting results.

[0048] The STA status indicator uses LEDs to visually display the sensor's operating status: if the output indicator is off but the STA status indicator is on, it indicates no object is being detected; if the output indicator is on but the STA status indicator is off, it indicates a weak signal from the receiver, and the product is operating at a critical state. The object should be moved closer to the detection surface to ensure reliable operation; if neither the output indicator nor the STA status indicator is on, it indicates a weak signal from the receiver, and the product is operating at a critical state. The object should be moved away from the detection surface to ensure reliable operation. The STA status indicator uses high-brightness LEDs with a 120° viewing angle, ensuring clear visibility even in strong light. The counter's output is connected to an OutputInverter, which converts the counter's signal into a level suitable for external devices and outputs it through the OUT terminal. The OutputInverter also connects to PN and INV, which are used for further processing and conversion of the output signal to ensure signal compatibility and stability.

[0049] Overcurrent Detection and Main Logic Control: The OUT terminal is simultaneously connected to an Overcurrent Detector, which monitors the current in the output circuit. When the current exceeds a set safety threshold, a protection mechanism is triggered to prevent circuit damage due to overcurrent. The output signal of the Overcurrent Detector is connected to the Main Logic unit, which is the control core of the entire sensor. It receives signals from various modules, performs logic processing and judgment, and generates corresponding control signals. The Main Logic is connected to the OSC (Oscillator) and the LED driver unit. The OSC generates a stable clock signal, providing a reference for the timing control of the entire system. The LED driver unit drives the LED to emit light according to the control signals from the Main Logic. As a light source, the LED's luminous intensity, frequency, and other parameters can be adjusted through the Main Logic to adapt to different dark area detection environments. For example, in dimly lit areas, the luminous intensity of the LED can be increased to enhance the reflected light signal from the target object; in scenarios requiring energy saving, the luminous frequency or intensity of the LED can be reduced.

[0050] Therefore, this utility model has the following advantages:

[0051] Effective suppression of background light interference: By employing a dual photodiode design (PDA and PDB) to receive target and background signals respectively, and utilizing the (AB) / (A+B) algorithm to enhance the difference component, interference from ambient background light can be significantly suppressed. This algorithm addresses the common-mode characteristics of background light by using differential calculation and normalization processing to effectively extract the target signal, reducing the impact of background light on the detection results, enabling the sensor to maintain high detection accuracy even in complex lighting environments.

[0052] Adaptive gain control enhances detection sensitivity: The gain control unit, composed of AMP1 and AMP2, dynamically adjusts the gain according to the intensity of the input signal, effectively amplifying weak target signals in dark areas. In low-light environments, it automatically increases the gain to enhance the signal amplitude and prevent weak signals from being drowned out by noise. When the light intensity changes, it adaptively adjusts the gain to ensure the linear range of signal processing and improve the sensor's adaptability to different dark environments.

[0053] Hysteresis control enhances detection stability: The introduction of the HYS hysteresis comparator creates a hysteresis range during signal detection, effectively preventing false triggering and output oscillation caused by signal fluctuations. This allows the sensor to maintain a stable output state when faced with slight environmental changes or signal noise, improving the reliability of detection results.

[0054] Integrated control modules enable intelligent detection: The coordinated operation of control modules such as the AD controller, counter, and main logic unit enables intelligent adjustment of sensor operating parameters and automated control of the detection process. For example, based on the real-time detected ambient light intensity and signal strength, the operating mode of the selection gate, gain parameters, and LED light intensity are automatically adjusted, allowing the sensor to adapt to different dark area detection scenarios without manual intervention, thereby improving detection efficiency and accuracy.

[0055] Overcurrent protection ensures system safety: The overcurrent detector provides a reliable protection mechanism for the sensor circuit. When an overcurrent occurs in the output circuit, it can trigger the protection in time to prevent component damage, extend the service life of the sensor, and improve the safety and stability of the system.

[0056] Wide applicability: The technical solution of this utility model is not only suitable for dark environments with varying light intensities, but also capable of handling complex background light distribution. Through reasonable design of the parameters and control logic of each module, this sensor can be widely applied in various scenarios such as object detection on industrial production lines, cargo positioning in smart warehousing, and intrusion detection in security systems, demonstrating high practical value and market potential.

[0057] The above embodiments are merely illustrative of the principles and effects of this utility model and are not intended to limit the scope of this utility model. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this utility model. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this utility model should still be covered by the claims of this utility model.

Claims

1. A background suppression photoelectric sensor for improving dark area detection capability, characterized in that: It includes a signal input module, a signal amplification and processing module, a control module, and an output module; the signal input module is electrically connected to the signal amplification and processing module, and the control module is electrically connected to both the signal amplification and processing module and the output module. The signal input module includes a PDA photodiode IV conversion unit and a PDB photodiode IV conversion unit, which are used to receive the light signal reflected from the target object and the ambient background light signal, respectively, and convert the light signal into a voltage signal. The signal amplification and processing module includes an (AB) / (A+B) operation unit, a selection gate, a gain control unit, a hysteresis control unit, and a level detection unit. The (AB) / (A+B) operation unit receives the voltage signal output from the signal input module and performs calculations. The selection gate receives the processed signal and switches the operating mode. The gain control unit dynamically adjusts the gain of the signal output from the selection gate. The hysteresis control unit and the level detection unit sequentially perform stability processing and threshold detection on the gain-adjusted signal. The control module includes an AD controller, a counter, a main logic unit, and an oscillator. The AD controller controls the switching of the operating modes of the selection gate. The counter counts the valid signals output by the level detection unit. The main logic unit receives signals from each module and generates control commands. The oscillator provides a timing reference. The output module includes an output inverter, an overcurrent detector, and an LED driver unit. The output inverter converts the counter output signal and outputs it through the OUT terminal. The overcurrent detector monitors the current of the output circuit, and the LED driver unit drives the LED light source to emit light.

2. The background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: Both the PDA photodiode IV conversion unit and the PDB photodiode IV conversion unit use transimpedance amplifiers to achieve current-to-voltage conversion.

3. The background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The gain control unit includes two variable gain amplifiers, AMP1 and AMP2, and the main logic unit dynamically adjusts the gain parameters of the two amplifiers according to the signal strength.

4. The background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The hysteresis control unit is a hysteresis comparator. By setting upper and lower thresholds, a hysteresis range is formed to avoid output jumps caused by minor signal fluctuations.

5. A background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The control module also includes a STA status indicator light, which is a high-brightness LED with a viewing angle of up to 120°, used to display the sensor's working status.

6. A background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The output inverter is also connected to PN and INV signal processing units to optimize the compatibility and stability of the output signal.

7. A background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The main logic unit is electrically connected to the LED driver unit, and can adjust the luminous intensity and frequency of the LED light source according to the ambient light intensity.

8. A background suppression photoelectric sensor for improving dark area detection capability according to claim 1, characterized in that: The processing cycle of the (AB) / (A+B) operation unit is 10μs, which is used to suppress background light common-mode noise in real time.

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