A miniature digital CMOS laser displacement sensor circuit system

Abstract

The embodiment of the present application provides a miniature digital CMOS laser displacement sensor circuit system, including a processor module, a CMOS image sensor module, a constant current control module, an input-output module, and a power supply module for supplying power to the above modules, wherein the CMOS image sensor module is electrically connected to the constant current control module, the constant current control module and the input-output module are electrically connected to the processor module respectively, the constant current control module includes a semiconductor laser diode constant current drive circuit and a feedback unit electrically connected to the processor module, and the CMOS image sensor module and the semiconductor laser diode constant current control circuit are electrically connected to the feedback unit respectively. The miniature digital CMOS laser displacement sensor circuit system of the present invention enables automatic gain adjustment of the brightness of the semiconductor laser diode light-emitting chip through circuit configuration, thereby achieving high-precision measurement performance of the sensor.

Description

Technical Field

[0001] The invention relates to the technical field of displacement sensor circuit systems, in particular to a miniature digital CMOS laser displacement sensor circuit system. Background Art

[0002] Laser displacement sensors have excellent performance in non-contact online displacement measurement. With the continuous development of optoelectronic technology, the circuit system, as the core component of the displacement sensor, is also constantly updated.

[0003] Prior art CN106441110A provides a high-precision laser displacement sensor system based on CMOS, which mainly solves the problems of complicated peripheral circuits and low measurement accuracy in the prior art. The system consists of a power module, a semiconductor laser diode module, a digital signal processing module, an image sensor module, a direct triangulation module and a differential subtraction circuit, wherein the semiconductor laser diode module is irradiated on the image sensor module by the infrared laser of the direct triangulation module, the image sensor module completes the spot perception and converts the light signal into an analog electrical signal, and then outputs it to the digital signal processing module for AD acquisition through the differential subtraction circuit, and the digital signal processing module performs calculations on the collected digital signal and outputs the actual digital displacement. The technical advantage is that the CMOS image sensor is used as a photoelectric device, and the measurement advantages of the CMOS image sensor are utilized to improve the measurement accuracy to a certain extent.

[0004] However, in the above technology, the constant current source circuit and the slow start circuit are used as the processing circuit of the input current of the diode, which can only ensure the provision of a stable current to the input end of the diode, but cannot ensure the stability of the brightness of the light spot on the photosensitive element, thereby making the detection result unstable, resulting in low detection accuracy and poor accuracy of the detection result. Summary of the invention

[0005] The purpose of the present invention is to solve the above-mentioned problems and provide a miniature digital CMOS laser displacement sensor circuit system, which can realize automatic gain adjustment of the light brightness on the photosensitive element through the cooperation of a semiconductor laser diode constant current drive circuit and a feedback unit, ensure the stability of light, and improve the measurement accuracy and accuracy of the detection results.

[0006] To achieve the above-mentioned purpose, the present invention provides a miniature digital CMOS laser displacement sensor circuit system, comprising a processor module, a CMOS image sensor module, a constant current control module, an input / output module, and a power supply module for supplying power to the above modules, wherein the CMOS image sensor module is electrically connected to the constant current control module, the constant current control module and the input / output module are electrically connected to the processor module, respectively, the constant current control module comprises a semiconductor laser diode constant current drive circuit and a feedback unit electrically connected to the processor module, and the CMOS image sensor module and the semiconductor laser diode constant current control circuit are electrically connected to the feedback unit, respectively.

[0007] Preferably, the feedback unit includes a resistor R1, a resistor R33, a potentiometer VR1, a resistor R13, a bias current amplifier U6 whose inverting input terminal is connected to the resistor R1, a resistor R10 connected to the output terminal of the bias current amplifier U6, and a feedback integration capacitor C28 connected to the resistor R10, which are connected in sequence; the resistor R1 is connected to the inverting input terminal of the bias current amplifier U6; the resistor R33, the potentiometer VR1, and the feedback integration capacitor C28 are connected to the bias current amplifier U6 in parallel; and the non-inverting input terminal of the bias current amplifier U6 is connected to a reference circuit.

[0008] Preferably, the bias current amplifier U6 includes a first amplifier U6A and a second amplifier U6B, the resistor R1 is connected to the inverting input terminal of the second amplifier U6B, the reference circuit is connected to the non-inverting input terminal of the second amplifier U6B, one end of the resistor R10 is connected to the output terminal of the second amplifier U6B, the other end of the resistor R10 is connected to the inverting input terminal of the first amplifier U6A, and the feedback integration capacitor C28 is connected in parallel with the first amplifier U6A.

[0009] Preferably, the light-emitting chip LD of the semiconductor laser diode in the semiconductor laser diode constant current control circuit is electrically connected to the processor module via a transistor for light-emitting control, and is electrically connected to the feedback unit via a transistor for duty cycle adjustment.

[0010] Preferably, the power supply module comprises a power supply circuit and a feedback circuit connected to an output end of the power supply circuit.

[0011] Preferably, the feedback circuit comprises high-precision feedback resistors RF1 and RF2 connected in series between the output terminal of the power supply circuit and the ground terminal.

[0012] Preferably, the input-output module comprises an analog output unit, which is a current and voltage analog output control circuit, and the current and voltage analog output control circuit is used to output 4-20mA current analog quantity and / or 0-5VDC voltage analog quantity.

[0013] Preferably, the processor module is a 32-bit high-speed processor, and the system also includes a human-machine interface module electrically connected to the processor module, the human-machine interface module includes a 16-bit processor, and a multi-digit digital tube display screen, operation buttons, and a data storage unit electrically connected to the 16-bit processor respectively, and the 16-bit processor is electrically connected to the processor module.

[0014] According to a miniature digital CMOS laser displacement sensor circuit system of the present invention, a constant current source and constant power drive of a laser diode are realized through a semiconductor laser diode constant current drive circuit and a feedback unit, and then the brightness of light is automatically adjusted by gain, so that the sensor maintains the consistency of diode brightness under long-term operation, ensures the stability of light, improves measurement accuracy, and thus ensures the accuracy of measurement;

[0015] Furthermore, a power supply circuit with feedback is provided, and automatic gain adjustment is performed through feedback signals to output a stable voltage, thereby providing a stable and reliable working power supply for all other circuits, ensuring that the sensor circuit is not affected by external fluctuations during operation, and improving measurement stability;

[0016] Furthermore, an analog output unit is provided to realize dual analog output and a human-machine interface module is provided. Data processing is performed by a 32-bit high-speed processor with high-speed computing capability and multi-task real-time processing capability, so that the user can complete the control of the analog quantity by operating buttons to change the settings, which provides convenience for the user. In addition, during use, the user does not need to add an external single analog output device, thereby reducing the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings constituting a part of this application are used to provide a further understanding of the present invention. 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:

[0018] Figure 1 A system block diagram of an embodiment of a circuit system of a miniature digital CMOS laser displacement sensor of the present application;

[0019] Figure 2 for Figure 1 Circuit diagram of constant current control module;

[0020] Figure 3 for Figure 1 Circuit diagram of the power module;

[0021] Figure 4 for Figure 1 Circuit diagram of medium negative voltage power supply circuit;

[0022] Figure 5 for Figure 1 Circuit diagram of the boost power supply circuit;

[0023] Figure 6 for Figure 1 A circuit diagram of a switch quantity input circuit of a switch quantity input and output unit;

[0024] Figure 7 for Figure 1 A circuit diagram of a switching quantity output circuit of a switching quantity input and output unit;

[0025] Figure 8 for Figure 1 Circuit diagram of analog output unit;

[0026] Fig. 9 for Figure 1 Circuit diagram of the human-machine interface module;

[0027] Fig.10 for Figure 1 Circuit diagram of the image sensing circuit built into the line array CMOS image sensor;

[0028] Fig.11 for Figure 1 Optical path diagram of the CMOS sensing optical path;

[0029] Explanation of reference numerals: a-laser diode, b-focusing lens, c-glass window, d-object to be measured, e-bandpass filter, f-receiving objective lens, g-photosensitive element, h-reflecting mirror. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0031] Embodiment: A micro digital CMOS laser displacement sensor circuit system, referring to Figure 1As shown, it includes a processor module, a CMOS image sensor module, a constant current control module, an input / output module, and a power module for supplying power to the above modules. In this embodiment, the processor module uses a 32-bit high-speed processor, and uses a STM32F401CBU6 chip with a package model of QFN48. It should be emphasized that the 32-bit high-speed processor applicable to this embodiment is not limited to this model, but is a 32-bit processor that can be obviously thought of by personnel in the technical field and is commonly used in the technical field. The CMOS image sensor module is electrically connected to the constant current control module, and the constant current control module and the input / output module are respectively connected to the 12-bit ADC circuit in the 32-bit high-speed processor.

[0032] Specifically, the constant current control module includes a semiconductor laser diode constant current drive circuit and a feedback unit electrically connected to a 32-bit high-speed processor, and the CMOS image sensor module and the semiconductor laser diode constant current control circuit are electrically connected to the feedback unit respectively. The semiconductor laser diode has three pins, including a light-emitting chip LD and a feedback receiving chip PD. In this embodiment, the feedback unit is used to detect changes in the detection environment of the feedback receiving chip PD end of the semiconductor diode, and feed back the change signal to the 32-bit high-speed processor. The processor adjusts the electrical parameters of the light-emitting chip LD end according to the received feedback signal, thereby adjusting the brightness of the LD light-emitting chip to make the light brighter or darker, so as to achieve constant current source and constant power drive.

[0033] As a preferred implementation of this embodiment, refer to Figure 2 As shown, the feedback unit includes a resistor R1, a resistor R33, a potentiometer VR1, a resistor R13, a bias current amplifier U6 whose inverting input terminal is connected to the resistor R1, a resistor R10 connected to the output terminal of the bias current amplifier U6, and a feedback integral capacitor C28 connected to the resistor R10, which are connected in sequence. The resistor R1 is connected to the inverting input terminal of the bias current amplifier U6, the resistor R33, the potentiometer VR1, and the feedback integral capacitor C28 are connected to the bias current amplifier U6 in parallel, and the non-inverting input terminal of the bias current amplifier U6 is connected to the reference circuit.

[0034] Further preferably, the bias current amplifier U6 includes a first amplifier U6A and a second amplifier U6B, the resistor R1 is connected to the inverting input terminal of the second amplifier U6B, the reference circuit is connected to the non-inverting input terminal of the second amplifier U6B, one end of the resistor R10 is connected to the output terminal of the second amplifier, the other end of the resistor R10 is connected to the inverting input terminal of the first amplifier U6A, and the feedback integration capacitor C28 is connected in parallel with the bias current amplifier U6A.

[0035] The reference circuit includes R2 and R3 connected in series, and the other end of R2 is energized, and the other end of R3 is grounded. R2 and R3 are reference voltage resistors in the reference circuit, and provide a reference voltage after being energized. The feedback integration capacitor C28 forms an integration circuit; VR1 is a potentiometer, and the brightness of the semiconductor laser diode is fine-tuned through the potentiometer VR1; the output end of the feedback unit is electrically connected to the 32-bit high-speed processor; the positive input end of the second amplifier U6B is connected to the collector end of the PNP transistor Q9; the emitter and base set of the PNP transistor Q9 are electrically connected to the 32-bit high-speed processor respectively, and the 32-bit high-speed processor adjusts the light-emitting duty cycle of the semiconductor diode through the transistor Q9; the output end of the first amplifier U6A is connected to the base set of the NPN transistor Q8, the emitter of the NPN transistor Q8 is connected to the emitter of the PNP transistor Q7, the base set of the PNP transistor Q7 is electrically connected to the 32-bit high-speed processor, the collector of the PNP transistor Q7 is connected to the light-emitting chip LD of the semiconductor laser diode, and the 32-bit high-speed processor determines whether to add a constant current source to the semiconductor laser diode through the switch quantity control of the transistor Q7. Through the setting of the constant current control module of this embodiment, a true constant current source constant power drive of the laser diode is realized, the brightness of the light is automatically adjusted by gain, the consistency of the brightness is maintained under long-term operation, the stability of the light is ensured, the precision is improved, and the accuracy of the measurement is ensured.

[0036] In this embodiment, the semiconductor laser diode in the semiconductor laser diode constant current control circuit, the light emitting chip LD is electrically connected to the 32-bit high-speed processor via a transistor for light emission control, and is electrically connected to the integration circuit via a transistor for duty cycle adjustment.

[0037] As a preferred implementation of this embodiment, refer to Figure 3 As shown, the power supply module includes a reverse polarity protection circuit, a feedback circuit, a surge voltage absorption circuit, and a power supply circuit which are connected in sequence. The power supply circuit is electrically connected to a 32-bit high-speed processor, a CMOS image sensor module, a constant current control module, and an input / output module for power supply.

[0038] In this embodiment, the reverse polarity protection circuit includes a reverse polarity protection diode connected in series with the input end of the power module, the surge voltage absorption circuit includes a varistor connected to the reverse polarity protection diode and grounded, and the feedback circuit includes high-precision feedback resistors RF1 and RF2 connected in parallel with the output end of the power supply circuit.

[0039] Specifically, the main features of the power module include a DC12V-DC24V wide voltage input, and a diode D6 is connected in series at the voltage input end, and the diode D6 realizes reverse polarity protection of the power input. A varistor R54 is arranged in parallel with the diode D6 and grounded, and an input surge voltage absorption circuit is formed by the varistor arranged in this way. The feedback circuit is composed of high-precision feedback resistors RF1 and RF2 arranged in the circuit. When the output voltage fluctuates, it is fed back to the chip U1 of the power module (it should be noted that U1 is a chip of the power circuit that can be obviously thought of by personnel in this technical field) for automatic gain adjustment, thereby outputting a stable 5VDC voltage. The power module with a feedback circuit provided by this embodiment realizes automatic gain adjustment of the supply voltage, provides a stable and reliable working power supply for the circuits of each module in the system, so that each module is not affected by external fluctuations during operation, while reducing power consumption and improving measurement stability.

[0040] As a preferred implementation of this embodiment, refer to Figure 1 As shown, the input-output module includes a surge absorption circuit, an output reverse connection protection circuit, an overcurrent protection circuit, a switch input-output unit, a negative voltage power supply circuit, a boost power supply circuit, an analog control circuit and an analog output unit, wherein the surge absorption circuit, the output reverse connection protection circuit, the overcurrent protection circuit, and the switch input-output unit are connected in sequence, the switch input-output unit is electrically connected to the 32-bit high-speed processor, the analog control circuit is electrically connected to the negative voltage power supply circuit, the boost power supply circuit, and the analog output unit, respectively, and the surge absorption circuit, the negative voltage power supply circuit, and the boost power supply circuit are electrically connected to the power module, respectively.

[0041] Specifically, refer to Figure 4 As shown, the input end of the negative voltage power supply circuit is connected to the output end of the power module, and the +5VDC voltage is input. After the circuit is processed, a -5VDC negative voltage is generated to provide a negative power supply for the single-power analog chip to meet the analog output function; refer to Figure 5 As shown, the input end of the boost power supply circuit is connected to the output end of the power module, and a +5VDC voltage is input. After circuit processing, a voltage higher than +5VDC is output. In this embodiment, the output voltage of the boost power supply circuit is a +11VDC voltage. The +11VDC voltage generated by the boost power supply circuit provides power for the current analog output, meeting its 4-20mA output current and 300 ohm load impedance technical requirements.

[0042] In this embodiment, the switch input and output unit includes: Figure 6 The switch input circuit shown and the switch output circuit connected to the switch input circuit are electrically connected to the surge voltage absorption circuit and the 32-bit high-speed processor respectively. Figure 7As shown, R22, R20, NPN transistor Q3, R15, R16, and R39 constitute an output short-circuit protection circuit. When the output is short-circuited, the voltage at the upper end of R22 rises sharply, which is fed back to the 32-bit high-speed processor through R20, NPN transistor Q3, R15, R16, and R39 to turn off the output; diode D2 provides output reverse connection protection, and diode D3 provides output surge voltage protection.

[0043] In this embodiment, reference Figure 8 As shown, the analog output unit is a current and voltage analog output control circuit, which can output 4-20mA current analog and / or 0-5VDC voltage analog through the control of the analog control unit.

[0044] Specifically, the input terminal VEE of the analog output unit is respectively connected to the output terminal of the negative voltage power supply circuit, and VDD is connected to the output terminal of the boost power supply circuit. The input voltage of the VEE terminal is -5VDC voltage, and the input voltage of the VDD terminal is +11VDC voltage. VEE and VDD are connected with a bidirectional diode D5, a grounded unidirectional diode D7, and an inductor L3. D5, D7, and L3 respectively play a protective role when outputting current analog quantities and voltage analog quantities to prevent interference from voltage fluctuations.

[0045] As a preferred implementation of this embodiment, refer to Fig. 9 As shown, the system also includes a human-machine interface module electrically connected to the 32-bit high-speed processor, the human-machine interface module includes a 16-bit processor, and a multi-digit digital tube display screen, operation buttons, and a data storage unit electrically connected to the 16-bit processor respectively, and the 16-bit processor is electrically connected to the 32-bit high-speed processor.

[0046] Specifically, the human-machine interface module is controlled by an independent microprocessor and is equipped with multiple LED indicators, multi-digit 7-segment LED digital tubes and buttons. The LED digital tubes display digital letters and symbols, and the buttons for humanized operation, in conjunction with a 32-bit high-speed processor with the ability to perform multiple tasks simultaneously, realize the multi-mode and multi-functional performance of the sensor.

[0047] In this embodiment, the CMOS image sensing module includes a linear array CMOS image sensor, a signal amplification circuit, and a high-speed ADC digital-to-analog conversion circuit connected in sequence. The input end of the linear array CMOS image sensor is connected to the CMOS sensing optical path, and the high-speed ADC digital-to-analog conversion circuit is electrically connected to the feedback unit. Fig.10 The image sensing circuit of the linear array CMOS image sensor in this embodiment is shown. The circuit is obvious to those skilled in the art or can be easily obtained by reading technical documents in this field, and its specific structure is not described here. However, it should be noted that this embodiment is not limited to the use of Fig.10The image sensing circuit shown and Fig.11 The sensing optical path shown is also applicable to other image sensing circuits and CMOS sensing optical paths that are obvious to those skilled in the art and are commonly used in the art. In this embodiment, laser a emits laser light, which is focused by focusing lens b and then irradiates the object d through window glass c. The laser light is emitted on the object d. The emitted laser light passes through bandpass filter e and enters the sensor. It passes through imaging objective lens f and irradiates the photosensitive element g. Part of the laser light is emitted on the photosensitive element g and is reflected back to the photosensitive element g by reflective element h.

[0048] Working principle: During the use of the sensor, the feedback receiving chip PD of the semiconductor laser diode detects the working power of the semiconductor laser diode in real time; when it is detected that the power of the semiconductor laser diode is attenuated (for example, when the brightness of the light-emitting chip LD may change due to temperature or other conditions), the light received by the feedback receiving chip PD also changes, and the feedback unit feeds back the change to the 32-bit high-speed processor. The 32-bit high-speed processor adjusts the duty cycle of the light-emitting chip LD by adjusting the voltage of the emitter and base set of the PNP transistor Q9, controls whether to add a constant current source to the semiconductor laser diode by adjusting the voltage of the base set of the PNP transistor Q7, and fine-tunes the brightness of the semiconductor laser diode by adjusting the potentiometer VR1, thereby changing the current of the semiconductor laser diode, further adjusting the brightness of the light-emitting chip LD (brightening or dimming), achieving constant current source constant power drive, improving the stability of electrical components during the detection process, and improving detection accuracy.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A miniature digital CMOS laser displacement sensor circuit system, comprising a processor module, a CMOS image sensor module, a constant current control module, an input / output module, and a power supply module for supplying power to the above modules, wherein the CMOS image sensor module is electrically connected to the constant current control module, and the constant current control module and the input / output module are electrically connected to the processor module, respectively, characterized in that: The constant current control module includes a semiconductor laser diode constant current drive circuit and a feedback unit electrically connected to the processor module, and the CMOS image sensor module and the semiconductor laser diode constant current control circuit are electrically connected to the feedback unit respectively; The light emitting chip LD of the semiconductor laser diode in the semiconductor laser diode constant current control circuit is electrically connected to the processor module via a transistor for light emission control, and is electrically connected to the feedback unit via a transistor for duty cycle adjustment; The power module includes a power supply circuit and a feedback circuit connected to the output terminal of the power supply circuit; the feedback circuit includes high-precision feedback resistors RF1 and RF2 connected in series between the output terminal of the power supply circuit and the ground terminal; The feedback unit includes a resistor R1, a resistor R33, a potentiometer VR1, a resistor R13, a bias current amplifier U6 whose inverting input terminal is connected to the resistor R1, a resistor R10 connected to the output terminal of the bias current amplifier U6, and a feedback integration capacitor C28 connected to the resistor R10, which are connected in sequence. The resistor R1 is connected to the inverting input terminal of the bias current amplifier U6, the resistor R33, the potentiometer VR1, and the feedback integration capacitor C28 are connected in parallel to the bias current amplifier U6, and the non-inverting input terminal of the bias current amplifier U6 is connected to a reference circuit.

2. The micro digital CMOS laser displacement sensor circuit system according to claim 1, characterized in that: The bias current amplifier U6 includes a first amplifier U6A and a second amplifier U6B, the resistor R1 is connected to the inverting input terminal of the second amplifier U6B, the reference circuit is connected to the non-inverting input terminal of the second amplifier U6B, one end of the resistor R10 is connected to the output terminal of the second amplifier U6B, the other end of the resistor R10 is connected to the inverting input terminal of the first amplifier U6A, and the feedback integration capacitor C28 is connected in parallel with the first amplifier U6A.

3. The micro digital CMOS laser displacement sensor circuit system according to claim 1, characterized in that: The input-output module comprises an analog output unit, which is a current and voltage analog output control circuit, and the current and voltage analog output control circuit is used to output 4-20mA current analog quantity and / or 0-5VDC voltage analog quantity.

4. The micro digital CMOS laser displacement sensor circuit system according to claim 1, characterized in that: The processor module is a 32-bit high-speed processor. The system also includes a human-machine interface module electrically connected to the processor module. The human-machine interface module includes a 16-bit processor, a multi-digit digital tube display screen, operation buttons, and a data storage unit electrically connected to the 16-bit processor respectively. The 16-bit processor is electrically connected to the processor module.

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